Risks of Vinclozolin Use to Federally Threatened
California Red-legged Frog
(Rana aurora draytonii)
Pesticide Effects Determination
Environmental Fate and Effects Division
Office of Pesticide Programs
Washington, D.C. 20460
October 14,2009
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Primary Authors:
Thomas Steeger, Ph.D., Senior Biologist
Kristina Garber, Biologist
Secondary Reviewers:
Marietta Echeverria, Risk Assessment Process Leader
Anita Pease, Senior Biologist
Branch Chief, Environmental Risk Assessment Branch 4:
Elizabeth Behl
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Table of Contents
1.0 EXECUTIVE SUMMARY 6
2.0 PROBLEM FORMULATION 13
2.1 PURPOSE 13
2.2 SCOPE 15
2.3 PREVIOUS ASSESSMENTS 16
2.4 STRESSOR SOURCE AND DISTRIBUTION 16
2.4.1 Environmental Fate and Transport Assessment 16
2.4.2 Mechanism of Action 23
2.4.3 Use Characterization 23
2.5 ASSESSED SPECIES 26
2.5.1 Distribution 26
2.5.2 Reproduction 29
2.5.3 Diet 29
2.5.4 Habitat 30
2.6 DESIGNATED CRITICAL HABITAT 31
2.7 ACTION AREA 32
2.8 AsSESSMENTENDPOINTS AND MEASURES OF ECOLOGICAL EFFECT 34
2.8.1 Assessment Endpoints for the CRLF 34
2.8.2 Assessment Endpoints for Designated Critical Habitat 37
2.9 CONCEPTUAL MODEL 39
2.9.1 Risk Hypotheses 39
2.9.2 Diagram 39
2.10 ANALYSIS PLAN 41
2.10.1 Measures to Evaluate the Risk Hypothesis and Conceptual Model 42
2.10.2 Data Gaps 45
3.0 EXPOSURE ASSESSMENT 45
3.1 LABEL APPLICATION RATES AND INTERVALS 45
3.2 SURFACE WATER EXPOSURE ASSESSMENT 46
3.2.1 Modeling Approach 46
3.2.2 Model Inputs for Vinclozolin Residues of Concern 46
3.2.3 Modeling Results 48
3.2.4 Surface Water Monitoring Data 48
3.3 GROUND WATER EXPOSURE ASSESSMENT 49
3.3.1 Modeling Approach 49
3.3.2 Modeling Results 49
3.3.3 Ground Water Monitoring Data 49
3.4 TERRESTRIAL EXPOSURE ASSESSMENT 49
3.5 ATMOSPHERIC TRANSPORT ASSESSMENT 50
3.5.1 Spray Drift 50
3.5.2 Volatilization 51
3.5.3 Air Monitoring Data 51
4.0 EFFECTS ASSESSMENT 51
4.1 EVALUATION OF AQUATIC ECOTOXICITY STUDIES FOR VINCLOZOLIN 53
4.1.1 Toxicity to Freshwater Fish 54
4.1.2 Toxicity to Freshwater Invertebrates 57
4.1.3 Toxicity to Aquatic Plants 58
4.2 TOXICITY OF VINCLOZOLIN TO TERRESTRIAL ORGANISMS 58
4.2.1 Toxicity to Birds 60
Toxicity to Mammals 62
4.2.2 Toxicity to Terrestrial Invertebrates 63
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4.2.3 Toxicity to Terrestrial Plants 63
4.3 TOXICITY OF 3,5-DCA 64
4.4 INCIDENT DATABASE REVIEW 65
4.5 ENDOCRINE DISRUPTOR EFFECTS 65
5.0 RISK CHARACTERIZATION 66
5.1 RISK ESTIMATION 66
5.1.1 Exposures in the Aquatic Habitat 66
5.1.2 Exposures in the Terrestrial Habitat 69
5.1.3 Primary Constituent Elements of Designated Critical Habitat 70
5.2 RISK DESCRIPTION 72
5.2.1 Direct Effects 75
5.2.2 Indirect Effects (via Reductions in Prey Base) 77
5.2.3 Indirect Effects (via Habitat Effects) 79
5.2.4 Modification to Designated Critical Habitat 79
5.2.5 Addressing the Risk Hypotheses 81
6.0 UNCERTAINTIES 81
6.1 EXPOSURE ASSESSMENT UNCERTAINTIES 81
6.1.1 Maximum Use Scenario 81
6.1.2 Aquatic Exposure Modeling of Vinclozolin 81
6.1.3 Total residues of concern 83
6.1.3 Measured concentrations of 3,5-DCA in surface water 83
6.1.5 Usage Uncertainties 83
6.1.6 Terrestrial Exposure Modeling of Vinclozolin 84
6.1.7 Spray Drift Modeling 84
6.2 EFFECTS ASSESSMENT UNCERTAINTIES 85
6.2.1 Age Class and Sensitivity of Effects Thresholds 85
6.2.2 Use of Surrogate Species Effects Data 85
6.2.3 Sub lethal Effects 86
6.2.4 Location of Wildlife Species 86
6.2.5 Potential Effects to Terrestrial and Riparian Plants 86
6.2.6 Toxicities of Vinclozolin Degradates 86
7.0 RISK CONCLUSIONS 87
8.0 REFERENCES 91
Appendices
Appendix A. Use verification memo from the Special Review and Reregistration Division.
Appendix B. The Risk Quotient Method and Levels of Concern
Appendix C. PRZM/EXAMS Input/Output files
Appendix D. Aquatic exposure modeling for vinclozolin and 3,5-DCA
Appendix E. Output from T-REX v. 1.4.1
Appendix F. List of citations accepted and rejected by ECOTOX criteria
Appendix G. Detailed spreadsheet of available ECOTOX open literature for vinclozolin
Appendix H. Summary of available ecotoxicity information for all vinclozolin degradates and formulated products
Attachments
Attachment 1: Status and Life History of California Red-legged Frog
Attachment 2: Baseline Status and Cumulative Effects for the California Red-legged Frog
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Tables
Table 1. Effects Determination Summary for Vinclozolin Use on Turf Grass and the CRLF 11
Table 2. Effects Determination Summary for Vinclozolin Use and CRLF Critical Habitat Impact Analysis 11
Table 3. Environmental fate half-lives relevant to vinclozolin and observed residues of concern 17
Table 4. Physical and chemical properties of vinclozolin and 3,5-DCA 18
Table 5. Koc data for vinclozolin, 3,5-DCA and metabolite E in different soils 21
Table 6. Assessment Endpoints and Measures of Ecological Effects 36
Table 7. Summary of Assessment Endpoints and Measures of Ecological Effect for Primary Constituent Elements of
Designated Critical Habitat 38
Table 8. PRZM/EXAMS input parameters relevant to the fate of vinclozolin 47
Table 9. PRZM/EXAMS input parameters relevant to the use of vinclozolin 48
Table 10. Input parameters for Scigrow v.2.3 used to represent vinclozolin residues of concern 49
Table 11. Upper-bound Kenega Nomogram EECs for Dietary- and Dose-based Exposures of the CRLF and its Prey
to Vinclozolin 50
Table 12. Freshwater Aquatic Toxicity Profile for Vinclozolin 53
Table 13. Categories of Acute Toxicity for Fish and Aquatic Invertebrates 54
Table 14. Terrestrial Toxicity Profile for Vinclozolin 59
Table 15. Categories of Acute Toxicity for Avian and Mammalian Studies 59
Table 16. Summary of Direct Effect RQs forthe Aquatic-phase CRLF 67
Table 17. Risk Estimation Summary for Vinclozolin Direct and Indirect Effects to CRLF 73
Table 18. Risk Estimation Summary for vinclozolin-PCEs of Designated Critical Habitat for the CRLF 74
Table 19. Chronic, dietary-based RQs for terrestrial-phase CRLF. RQs generated using T-HERPS 76
Table 20. Effects Determination Summary for Vinclozolin Use and the CRLF 88
Table 21. Effects Determination Summary for Vinclozolin Use and CRLF Critical Habitat Impact Analysis 89
Figures
Figure 1. Structures of vinclozolin residues of concern 19
Figure 2. Total annual use of vinclozolin in California between 1996 - 2007. California Department of Pesticide
Regulation 25
Figure 3. Pounds of vinclozolin applied in a single year for "landscape maintenance" in CA from 1999 to 2006.
From CA PUR 25
Figure 4. Recovery Unit, Core Area, Critical Habitat, and Occurrence Designations for CRLF 28
Figure 5. CRLF Reproductive Events by Month 29
Figure 6. Conceptual Model for Vinclozolin Effects on Terrestrial Phase of the CRLF 40
Figure 7. Conceptual Model for Vinclozolin Effects on Aquatic Phase of the CRLF 41
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1.0 Executive Summary
The purpose of this assessment is to evaluate potential direct and indirect effects on the
California red-legged frog (Rana aurora draytonii) (CRLF) arising from FIFRA regulatory
actions regarding use of vinclozolin on turf. In addition, this assessment evaluates whether these
actions can be expected to result in modification of the species' designated critical habitat. This
assessment was completed in accordance with the U.S. Fish and Wildlife Service (USFWS) and
National Marine Fisheries Service (NMFS) Endangered Species Consultation Handbook
(USFWS/NMFS, 1998 and procedures outlined in the Agency's Overview Document (U.S. EPA,
2004).
The CRLF was listed as a threatened species by USFWS in 1996. The species is endemic to
California and Baja California (Mexico) and inhabits both coastal and interior mountain ranges.
A total of 243 streams or drainages are believed to be currently occupied by the species, with the
greatest numbers in Monterey, San Luis Obispo, and Santa Barbara counties (USFWS, 1996) in
California.
Vinclozolin is a non-systemic fungicide currently registered in the United States for use on
canola and turf (industrial lawns and golf courses). Applications to residential turf grass are
prohibited. Labels also prohibit applications of vinclozolin to canola in California. Therefore,
uses on turf grass (industrial lawns and golf courses) are considered as part of the federal action
evaluated in this assessment. From 1999 to 2006, an annual average of 709 Ibs of vinclozolin
were applied for landscape maintenance in the state of California.
The product label relevant to vinclozolin use on turf grass indicates that single applications of
vinclozolin should be made at a maximum of 1.35 Ibs a.i./A with intervals of 10-28 days. The
label indicates that the product should be applied at a maximum seasonal rate of 4 Ibs a.i./A,
which is equivalent to 3 applications of 1.35 Ibs a.i./A. Applications are made by ground spray.
Applications by air and by chemigation are prohibited.
Available laboratory studies for vinclozolin indicate that it degrades via hydrolysis quickly in
neutral water (half-life =1.3 d). In aerobic and anaerobic environments, vinclozolin breaks
down via microbial degradation, with half-lives ranging 17.6-134 days. Vinclozolin can also be
degraded via photolysis, with half-lives of 18.1 and 27.2 days in soil and aqueous environments,
respectively. Vinclozolin has several major degradates, including metabolites B (N-3,5-
dichlorophenyl)carbamic acid(l-carboxy-l-methyl)-2-propenyl ester), E (N-3,5-dichlorophenyl)-
2-hydroxy-2-methyl-3-butenoic acid amide), S (N-(3,5-dichlorophenyl)-5-methyl-2,4-
oxazolidinedione) and 3, 5-dichloroanaline (3,5-DCA). There are no data available on the
persistence of metabolites B, E and S. A limited amount of data are available to characterize the
environmental fate of 3,5-DCA.
According to the Reregi strati on Eligibility Decision (RED) for vinclozolin, there is evidence that
vinclozolin binds fairly weakly to the androgen receptor but that metabolites B and E, which
occur in mammals, plants, and soil are responsible for much of the antiandrogenic activity
attributed to vinclozolin. The antiandrogenic mode of action of vinclozolin and several of its
degradates can lead to reproductive effects across a range of taxa. Therefore, vinclozolin,
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metabolite B, and metabolite E may have similar modes of action and the sum of their residues is
considered when assessing exposures of non-target organisms to vinclozolin. The vinclozolin
degradate 3,5-DCA is classified as a carcinogen. It is unknown whether 3,5-DCA would have a
similar mode of action compared to vinclozolin, metabolite B, and metabolite E. In addition, it is
unknown whether or not Metabolites F and S will have similar modes of action compared to
vinclozolin and 3,5-DCA. For the purpose of this assessment, vinclozolin as well as 3,5-DCA are
considered to be of concern for posing risks to non-target organisms. Because all other major
degradates of vinclozolin contain the 3,5-DCA moiety, the other major degradates of vinclozolin
(including Metabolites B, E, F and S) are also considered to be of concern. In this assessment,
EECs are generated to represent vinclozolin's total residues of concern.
In regards to the transport of vinclozolin in the environment, based on available soil partitioning
data, vinclozolin and its residues of concern have the potential to move from treatment sites to
non-target areas via runoff and leaching. Volatilization and bioaccumulation are unlikely to be
major routes of transport for vinclozolin and its degradates.
Since CRLFs exist within aquatic and terrestrial habitats, exposure of the CRLF, its prey and its
habitats to vinclozolin and degradates of concern are assessed separately for the two habitats.
Tier-II aquatic exposure models are used to estimate high-end exposures of vinclozolin in
aquatic habitats resulting from runoff and spray drift from different uses. Peak model-estimated
one-in-ten year environmental concentrations for vinclozolin use on turf grass are 9.75 |ig/L for
vinclozolin alone, 30.7 |ig/L for vinclozolin + metabolite B + metabolite E and 13.2 |ig/L for
3,5-DCA. No California-specific water monitoring data are available for vinclozolin or
metabolites B, E, F or S; however, data are available for 3,5-DCA from the U. S. Geological
Survey's (USGS) National Water Quality Assessment (NAWQA) program. The maximum
concentration of 3,5-DCA reported by NAWQA for California surface waters is 0.03 |ig/L. This
value is approximately 3 orders of magnitude lower than the maximum model-estimated
environmental concentration for 3,5-DCA. Also, there is uncertainty regarding the source of the
measured 3,5-DCA as it could be attributed to use of vinclozolin or iprodione (a fungicide that is
also used in California).
To estimate vinclozolin exposures to the terrestrial-phase CRLF, and its potential prey resulting
from uses involving vinclozolin applications, the T-REX model is used. AgDRIFT is also used
to estimate deposition of vinclozolin on terrestrial and aquatic habitats from spray drift. The T-
HERPS model is used to allow for further characterization of dietary exposures of terrestrial-
phase CRLFs relative to birds.
The effects determination assessment endpoints for the CRLF include direct toxic effects on the
survival, reproduction, and growth of the CRLF itself, as well as indirect effects, such as
reduction of the prey base or modification of its habitat. Direct effects to the CRLF in the
aquatic habitat are based on toxicity information for freshwater fish, which are generally used as
a surrogate for aquatic-phase amphibians. In the terrestrial habitat, direct effects are based on
toxicity information for birds, which are used as a surrogate for terrestrial-phase amphibians.
Given that the CRLF's prey items and designated critical habitat requirements in the aquatic
habitat are dependant on the availability of freshwater aquatic invertebrates and aquatic plants,
toxicity information for these taxonomic groups is also discussed. In the terrestrial habitat,
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indirect effects due to depletion of prey are assessed by considering effects to terrestrial insects,
small terrestrial mammals, and frogs. Although indirect effects due to modification of the
terrestrial habitat are generally characterized by available data for terrestrial monocots and
dicots, a lack of data on the effects of vinclozolin on terrestrial plants prevents this
characterization and as such, risk is presumed for terrestrial plants.
Vinclozolin is moderately toxic to freshwater fish and invertebrates on an acute exposure basis.
The no observed adverse effect concentration (NOAEC) for chronic effects to the fathead
minnow is 60 |ig/L, with a lowest observed adverse affect concentration (LOAEC) of 255 |ig/L
based on an increase in plasma vitellogenin in females and decreased testicular weights relative
to body weights, (i.e., gonadal-somatic index) in males. Both of these effects can impact
reproductive fitness/success. At higher concentrations female fish exposed to 450 |ig/L in this
study exhibited atresia of 90% of their oocytes and failed to reproduce. As such, exposure to
vinclozolin may lead to a direct reduction in CRLF reproductive success and affect the
availability of prey items. Available chronic toxicity data for aquatic invertebrates include a
NOAEC of 790 |ig/L, with a LOAEC of 1400 |ig/L based on impaired reproduction and
reductions in growth. The ECso for algae exposed to vinclozolin is <1060 |ig/L, based on
stimulated growth. For aquatic vascular plants, the ECso is >900 |ig/L, based on stimulated
growth. The increased growth of aquatic plants can lead to increased shading and compromised
water quality.
Vinclozolin is practically non-toxic to birds on an acute oral and subacute dietary exposure basis,
and practically non-toxic to mammals on an acute oral exposure basis. On an acute contact
exposure basis, vinclozolin is practically non-toxic to honeybees. The NOAEC for chronic
effects to the northern bobwhite quail is 50 mg/kg-diet, with a LOAEC of 125 mg/kg-diet based
on reduced number of eggs laid, decreased eggshell thickness and reduced survival of hatchlings.
The no observed adverse effect level (NOAEL) for the laboratory rat is 30 mg/kg/day. The
lowest observed adverse effect level (LOAEL) of 96 mg/kg/day is based on genital/reproductive
tract malformations and reproductive failure in male rats and is used to estimate potential chronic
effects on small mammals that serve as prey for CRLF.
At this time, no toxicity data are available to characterize the effects of metabolites B, E, F or S,
to non-target organisms. Therefore, it is assumed that data available for vinclozolin are
representative of effects to non-target organisms that may be caused by these metabolites that
have structures similar to the parent compound. Limited toxicity data are available for 3,5-DCA
showing that it is less toxic than the parent compound, and it is assumed that this chemical has a
different mode of action compared to vinclozolin.
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
vinclozolin use within the action area has the potential to adversely affect the CRLF and its
designated critical habitat via direct toxicity or indirectly based on direct effects to its food
supply (i.e., freshwater invertebrates, algae, fish, frogs, terrestrial invertebrates, and mammals)
or habitat (i.e., aquatic plants and terrestrial upland and riparian vegetation). When RQs for each
particular type of effect are below LOCs, the pesticide is determined to have "no effect" on the
CRLF. Where RQs exceed LOCs, a potential to cause adverse effects is identified, leading to a
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conclusion of "may affect." If a determination is made that use of vinclozolin 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 May Affect, and Likely to
Adversely Affect determination for the CRLF from the use of vinclozolin. 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 chronic direct effects on the terrestrial-phase
CRLF and indirect effects on terrestrial-phase CRLF due to chronic effects on prey items, the use
of vinclozolin on turf grass (specifically industrial lawns and golf courses) in California is
considered likely to adversely affect the CRLF. Additionally, there is uncertainty (due to a lack
of data) regarding the potential effects of vinclozolin on terrestrial plants and because of this
uncertainty, the use of vinclozolin may result in habitat modification. It should be noted that the
lack of terrestrial plant data renders the risk conclusions for habitat modification highly
uncertain. A summary of the risk conclusions and effects determinations for the CRLF and its
critical habitat is presented in
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Table 1 and Table 2. Further information on the results of the effects determination is included
as part of the Risk Description in Section 5.2. Given the LAA determination for the CRLF and
potential modification of designated critical habitat, a description of the baseline status and
cumulative effects for the CRLF is provided in Attachment II.
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Table 1. Effects Determination Summary for Vinclozolin Use on Turf Grass and the CRLF.
Assessment
Endpoint
Effects
Determination
Basis for Determination
Survival,
growth, and/or
reproduction
of CRLF
individuals
May affect,
likely to
adversely
affect (LAA)
Potential for Direct Effects
Aquatic-phase (Eggs, Larvae, and Adults):
Based on available data, both acute and chronic RQ values are below acute and chronic
risk LOCs. As such, vinclozolin use on turf is determined to have no direct effect on
aquatic-phase CRLF.
Terrestrial-phase (Juveniles and Adults):
Although vinclozolin is considered practically nontoxic to terrestrial-phase amphibians
(based on avian data used as a surrogate) on an acute oral and sub-acute dietary
exposure basis, chronic RQs based on impaired reproduction exceed the chronic risk
LOG by a factor of 9X. EECs are also sufficient to exceed the level where reproductive
effects were observed in birds (the LOAEC). As such, the use of vinclozolin on turf
grass in California is determined to be likely to adversely affect terrestrial-phase CRLF
due to direct chronic effects on reproduction.
Potential for Indirect Effects
Aquatic prey items, aquatic habitat, cover and/or primary productivity
Acute and chronic RQ values are below the acute and chronic risk LOCs for freshwater
invertebrates. RQ values for non-vascular and vascular aquatic plants are below the
LOG and/or vinclozolin is not expected to adversely affect the aquatic plant
community. Given that vinclozolin does not directly affect aquatic invertebrates or
vertebrates, vinclozolin is determined to have no effect on fish and aquatic-phase
amphibians that serve as prey for CRLF.
Terrestrial prey items, riparian habitat
Although vinclozolin is practically nontoxic to terrestrial-phase amphibians and
mammals on an acute exposure basis, chronic RQs based on impaired reproduction
exceed the chronic risk LOG by a factor of 9X for terrestrial-phase amphibians and
factors as high as 12X for small mammals that serve as prey for CRLF. In addition,
because of uncertainty regarding the potential effects of vinclozolin on terrestrial plants,
risk is presumed for the riparian habitat on which CRLF depend. As such, the use of
vinclozolin on turf in California is determined to be likely to adversely affect the CRLF
through indirect effects on prey and habitat.
Table 2. Effects Determination Summary for Vinclozolin Use and CRLF Critical Habitat
Impact Analysis.
Assessment
Endpoint
Modification of
aquatic -phase
PCE
Modification of
terrestrial-phase
PCE
Effects
Determination
Habitat
Modification
Basis for Determination
Based on the weight of evidence, the use of vinclozolin on turf grass in California is
determined to have no adverse effect on aquatic plants; however, there is uncertainty
regarding the potential effects of vinclozolin on terrestrial plants. Because of this
uncertainty, risk is presumed and there is a potential for habitat modification due to
effects on riparian cover surrounding aquatic areas.
There is uncertainty regarding the potential effects of vinclozolin on terrestrial plants.
Because of this uncertainty, risk is presumed and there is a potential for habitat
modification due to effects on riparian cover.
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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 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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2.0 Problem Formulation
Problem formulation provides a strategic framework for the risk assessment. By identifying the
important components of the problem, it focuses the assessment on the most relevant life history
stages, habitat components, chemical properties, exposure routes, and endpoints. The structure
of this risk assessment is based on guidance contained in U.S. EPA's Guidance for Ecological
Risk Assessment (U.S. EPA 1998), the Services' Endangered Species Consultation Handbook
(USFWS/NMFS 1998) and is consistent with procedures and methodology outlined in the
Overview Document (U.S. EPA 2004) and reviewed by the U.S. Fish and Wildlife Service and
National Marine Fisheries Service (USFWS/NMFS 2004).
2.1 Purpose
The purpose of this endangered species assessment is to evaluate potential direct and indirect
effects on individuals of the federally threatened California red-legged frog (Rana aurora
draytonii) (CRLF) arising from FIFRA regulatory actions regarding use of vinclozolin on turf
grass (specifically: golf courses and industrial parks). In addition, this assessment evaluates
whether use on turf grass is expected to result in modification of the species' designated critical
habitat. This ecological risk assessment has been prepared consistent with a settlement
agreement in the case Center for Biological Diversity (CBD) vs. EPA et al. (Case No. 02-1580-
JSW(JL)) settlement entered in Federal District Court for the Northern District of California on
October 20, 2006.
In this assessment, direct and indirect effects to the CRLF and potential modification to its
designated critical habitat are evaluated in accordance with the methods described in the
Agency's Overview Document (U.S. EPA 2004). Screening level methods include use of
standard models such as PRZM-EXAMS, T-REX and AgDRIFT all of which are described at
length in the Overview Document. In addition, T-HERPS is used to characterize risks to the
terrestrial-phase CRLF, using amphibian specific ingestion rates. Use of such information is
consistent with the methodology described in the Overview Document (U.S. EPA 2004), which
specifies that "the assessment process may, on a case-by-case basis, incorporate additional
methods, models, and lines of evidence that EPA finds technically appropriate for risk
management objectives" (Section V, page 31 of U.S. EPA 2004).
In accordance with the Overview Document, provisions of the ESA, and the Services'
Endangered Species Consultation Handbook, the assessment of effects associated with
registrations of vinclozolin 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 vinclozolin may potentially involve numerous areas
throughout the United States and its Territories. However, for the purposes of this assessment,
attention will be focused on relevant sections of the action area including those geographic areas
associated with locations of the CRLF and its designated critical habitat within the state of
California. As part of the "effects determination," one of the following three conclusions will be
reached regarding the potential use of vinclozolin in accordance with current labels:
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• "No effect";
• "May affect, but not likely to adversely affect"; or
• "May affect and likely to adversely affect".
Designated critical habitat identifies specific areas that have the physical and biological features,
(known as primary constituent elements or PCEs) essential to the conservation of the listed
species. The PCEs for CRLFs are aquatic and upland areas where suitable breeding and non-
breeding aquatic habitat is located, interspersed with upland foraging and dispersal habitat.
If the results of initial screening-level assessment methods show no direct or indirect effects (no
LOG exceedances) upon individual CRLFs or upon the PCEs of the species' designated critical
habitat, a "no effect" determination is made for use of vinclozolin 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
vinclozolin.
If a determination is made that use of vinclozolin 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 vinclozolin use sites) and
further evaluation of the potential impact of vinclozolin 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 vinclozolin is
expected to directly impact living organisms within the action area (defined in Section 2.7),
critical habitat analysis for vinclozolin is limited in a practical sense to those PCEs of critical
habitat that are biological or that can be reasonably linked to biologically mediated processes
(i.e., the biological resource requirements for the listed species associated with the critical habitat
or important physical aspects of the habitat that may be reasonably influenced through biological
processes). Activities that may modify critical habitat are those that alter the PCEs and
appreciably diminish the value of the habitat. Evaluation of actions related to use of vinclozolin
that may alter the PCEs of the CRLF's critical habitat form the basis of the critical habitat impact
analysis. Actions that may affect the CRLF's designated critical habitat have been identified by
the Services and are discussed further in Section 2.6.
14
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2.2 Scope
According to the reregi strati on eligibility decision (RED; USEPA 2000) on vinclozolin, the non-
systemic fungicide was once registered in the United States for use on raspberries, chicory grown
for Belgian endive, lettuce, kiwi, canola, succulent beans, and dry bulbs. Vinclozolin was also
registered for use on ornamentals and turf grass. Trade names included Ronilar®, Curalan®,
Vorlan® and Touche®. In 2000, the registrant, BASF, requested immediate cancellation of uses
on onions, raspberries and ornamentals, a phase-out of the California Section 24c uses on kiwi
and chicory by December 2001, and a phase-out of uses on lettuce and snap beans by July 2004.
After 2005, only uses on canola and turf remained. Product reregi strati on was completed in July
2006. Use of vinclozolin on canola is prohibited in California. Use on turf is limited to golf
courses and industrial park landscapes.
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 vinclozolin
in accordance with the approved product labels for California is "the action" relevant to this
ecological risk assessment.
Although current registrations of vinclozolin allow for use nationwide, this ecological risk
assessment and effects determination addresses currently registered uses of vinclozolin 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. At this time, the only vinclozolin use that is registered
for use in California is turf grass.
According to the Reregi strati on Eligibility Decision (RED) for vinclozolin, there is evidence that
vinclozolin binds fairly weakly to the androgen receptor but that metabolites B and E, which
occur in mammals, plants, and soil are responsible for much of the antiandrogenic activity
attributed to vinclozolin. The antiandrogenic mode of action of vinclozolin and several of its
degradates can lead to reproductive effects across a range of taxa. Therefore, vinclozolin,
metabolite B, and metabolite E may have similar modes of action and the sum of their residues is
considered when assessing exposures of non-target organisms to vinclozolin. 3,5-DCA is
classified as a carcinogen. It is unknown whether 3,5-DCA would have a similar mode of action
compared to vinclozolin, metabolite B, and metabolite E. In addition, it is unknown whether or
not Metabolites F and S will have similar modes of action compared to vinclozolin and 3,5-
DCA. For the purpose of this assessment, vinclozolin as well as 3,5-DCA are considered to be of
concern for posing risks to non-target organisms. Because all other major degradates of
vinclozolin contain the 3,5-DCA moiety, the other major degradates of vinclozolin (including
Metabolites B, E, F and S) are also considered to be of concern. In this assessment, EECs are
generated to represent vinclozolin's total residues of concern.
Vinclozolin does not have any registered products that contain multiple active ingredients. The
Agency does not routinely include, in its risk assessments, an evaluation of mixtures of active
15
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ingredients, either those mixtures of multiple active ingredients in product formulations or those
in the applicator's tank. In the case of the product formulations of active ingredients (that is, a
registered product containing more than one active ingredient), each active ingredient is subject
to an individual risk assessment for regulatory decision regarding the active ingredient on a
particular use site. If effects data are available for a formulated product containing more than
one active ingredient, they may be used qualitatively or quantitatively in accordance with the
Agency's Overview Document and the Services' Evaluation Memorandum (U.S., EPA 2004;
USFWS/NMFS 2004).
2.3 Previous Assessments
Vinciozolin was registered for use on ornamentals and turf in 1981, on stone fruits in 1982, on
potatoes in 1994, and on snap beans on 1997. The 1997 assessment noted that chronic toxicity
studies were unavailable for aquatic animals; however, chronic exposure to birds and mammals
resulted in reproductive effects that were characterized as anti-androgenic and indicative of a
chemical acting on endocrine-mediated processes. The RED was signed in October 2000 and
product reregi strati on was completed in July 2006.
Several emergency (Section 18) exemptions have been granted for the use of vinclozolin on
caneberries in Washington State (1985) and on canola (1997) in North Dakota and Minnesota.
Section 18 actions have noted that vincl ozolin and its degradation products could persist in the
environment and be available for runoff for several weeks to months post-application. In terms
of potential effects these assessments have stated that vinclozolin's use may pose a chronic risk
to bird and mammalian species and that the chemical acts on endocrine-mediated processes in
mammals
In the 2000 RED, vinclozolin was classified as a Group C chemical (possible human
carcinogen). The terminal metabolite of vinclozolin, 3,5-DCA was considered to have a
genotoxic mode of tumor induction based on its similarity to its structural analog
parachloraniline, which is carcinogenic in mammals.
2.4 Stressor Source and Distribution
2.4.1 Environmental Fate and Transport Assessment
Available laboratory studies for vinclozolin indicate that it degrades via hydrolysis quickly in
neutral water (half-life =1.3 d). In aerobic and anaerobic environments, vinclozolin breaks
down via microbial degradation, with half-lives ranging 17.6-352 days. Vinclozolin can also be
degraded via photolysis, with half-lives of 18.1 and 27.2 days in soil and aqueous environments,
respectively (Table 3). However, as described below, vinclozolin breaks down to several
degradates that are of concern for this assessment.
According the available environmental fate studies, vinclozolin has several major (form >10% of
applied) degradates (Table 3, Figure 1), including:
• metabolite B (N-3,5-dichlorophenyl)carbamic acid(l-carboxy-l-methyl)-2-propenyl ester),
• metabolite E (N-3,5-dichlorophenyl)-2-hydroxy-2-methyl-3-butenoic acid amide),
16
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• metabolite S (N-(3,5-dichlorophenyl)-5-methyl-2,4-oxazolidinedione) and
• 3,5-DCA.
In addition to these degradates, metabolite F (N-(3,5-dichlorophenyl)-2-methyl-2,3,4-
trihydroxybutanoic acid amide) was observed as a major degrade in an available
bioconcentration study with the bluegill sunfish. There are no data available on the persistence of
metabolites B, E, F and S. A limited amount of data are available to characterize the
environmental fate of 3,5-DCA It is assumed that metabolites B, E, F and S are intermediate
metabolites between vinclozolin and its ultimate degradation product, 3,5-DCA.
Based on available soil partitioning data, vinclozolin, metabolite E and 3,5-DCA have the
potential to move from treatment sites to non-target areas via runoff and leaching. Available
data indicate that vinclozolin residues of concern have the potential to be transported off site of
treatment areas via volatilization. The compound may also move off-site through spray drift.
Bioaccumulation is unlikely to be a concern for vinclozolin residues of concern. The physical
and chemical properties of vinclozolin and 3,5-DCA are provided in Table 4. The environmental
fate and transport data relevant to vinclozolin are summarized below and in Table 3.
Table 3. Environmental fate half-lives relevant to vinclozolin and observed residues of
concern.
Study
Hydrolysis
pH5
pH7
pH9
Aqueous
Photolysis
Soil Photolysis
Aerobic Soil
Metabolism
(loamy sand)
Anaerobic Soil
Metabolism
Aerobic aquatic
metabolism
Anaerobic aquatic
metabolism
Vinclozolin
Half-life (d)
41.8
1.3
0.026 (38 min)
27.2
18.1
35
41
53
53
352
17.6
Major degradates
(>10% of applied)
B&E
B&E
B&S
B
B
B
B
None reported
B
Minor degradates
(<10% of applied)
None reported
None reported
E
EandS
3,5-DCA, E and S
EandS
3,5-DCA, E
B, E, 3,5-DCA
3,5-DCA, E
Source (MRID)
41471006
44025301
42394706
41471008
44025302
135376
135376
135376
88288
43013001
44025303
41471009
Not available
134
B, 3,5-DCA
E&S
43013002
43255801
17
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Table 4. Physical and chemical properties of vinclozolin and 3,5-DCA.
Parameter (units)
Molecular weight (g/mol)
Vapor Pressure (torr)
Henry's Law Constant (atm-m3/mol) :
Solubility in Water (mg/L; @20°C)
Octanol-water partition coefficient (Kow)
Vinclozolin2
286.11
2.6 x ID'6
3.8 xlO'7
2.6
1054
3,5-DCA3
162.02
2.12xlQ-2
5.8 xlO'6
784
794
1 Calculated according to USEPA 20026 by: (VP *MW)-(760* solubility).
2 From registrant-submitted product chemistry data.
3 Estimated using EPISuite
18
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Vinclozolin
NH-C-O-C-COOH
I
HC=CHa
Metabolite B
Q CHa
II I
NH-C-C-OK
HC=CH8
Metabolite E
Metabolite S
Cl
0 CH3
II I
NH-C-C-CH-CHj
I I I
o o o
Cl
I I
H K
Metabolite F
!
H
NH2
3,5-DCA
Figure 1. Structures of vinclozolin residues of concern.
Hydrolysis
Vinclozolin hydrolyzes quickly in neutral (pH 7) and basic (pH 9) conditions, with reported half-
lives of 1.3 days and 38 minutes, respectively. Under acidic (pH 5) conditions, vinclozolin
hydrolyzes more slowly, with a half-life of 41.8 days. In the available hydrolysis study for
vinclozolin, metabolites B and E were observed as major degradates. No other degradates were
considered as analytes in this study. Peak levels of metabolite B were observed in pH 5, 7 and 9
at 40.5, 76.4, and 68.7% of applied, respectively. Peak levels of metabolite E were observed in
pH 5, 7 and 9 at 26.2, 16.8, and 20.9% of applied, respectively. In the 5-day study at pH 7,
19
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vinclozolin was hydrolyzed almost completely (approximately 93% of total residues) to
Metabolites B and E (MRIDs 41471006, 44025301). When metabolites B and E are considered
as residues of concern, vinclozolin residues of concern are stable to hydrolysis.
Photolysis
Vinclozolin degraded in the aqueous environment via photolysis with a half-life of 27.2 days. As
with the available hydrolysis study described above, metabolites B and E were observed as major
degradates, with peak levels of 26.6% and 10.5% of applied observed in the light treatment.
When considering the persistence of vinclozolin residues of concern, (this includes vinclozolin
and metabolites B and E), the aqueous photolysis half-life of these residues is 75.5 d. Given that
concentrations of metabolite E increased throughout the study, the 30 d study was not of
sufficient duration to capture the full formation and decline of metabolite E. The study was also
not of sufficient duration to capture the formation and decline of 3,5-DCA, which was not
detected during this study (MRID 42394706).
In a soil photolysis study, vinclozolin had a half-life of 18.1 days. Metabolites B and S were
observed as major degradates in the light treatment, with peak levels of 12.9% and 32.7% of
applied, respectively. Metabolite E was observed as a minor degradate, with peak levels of 5.3%
of applied. In the dark treatment, metabolite E was not detected (MRIDs 41471008, 44025302).
Microbial degradation (metabolism)
Under aerobic conditions, vinclozolin degraded slowly in soil (loamy sand), with a half-life of
352 days. Metabolites B and E and 3,5-DCA were observed during this study as minor
degradates (i.e., % of applied was <10%) (MRID 43013001 and 44025302). In a second aerobic
soil metabolism study, which was conducted using a German soil (loamy sand), vinclozolin
degraded more quickly than the previously described study, with a half-life of 53 days. In this
study, Metabolite B was observed as a major degradate, with a maximum observed level of
10.1% of applied. 3,5-DCA and Metabolite E were observed in the study; however their
concentrations were not reported (MRID 88288). In a third aerobic soil metabolism study,
vinclozolin degraded with half-lives of 35, 41, and 53 days on German soils (loamy sand).
Metabolite B was observed as a major degradate in both soils. 3,5-DCA and Metabolites E and
S were observed as minor degradates (MRID 136376).
An aerobic soil metabolism study of 3,5-DCA (on two different soils) showed little evidence that
3,5-DCA appreciably degraded over a 9-month period at 25°C (MRID 45239201). Apparent
dissipation was caused by a high level of unextracted residue. Unextracted residues accounted
for 66% and 81% of the applied in the two systems. The only residues that were distinguishable
from the parent amounted to only 4-5% of the applied 14C.
Under anaerobic conditions, vinclozolin degraded more quickly in soil (loamy sand) compared to
aerobic conditions. Available data indicate that vinclozolin has a half-life of 17.6 days in soil
under anaerobic conditions. In this study, metabolite B was observed as a major degradate, with
a peak observed level of 35.7%. 3,5-DCA and metabolite E were observed as minor degradates,
20
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with maximum observed levels of 3.8 and 3.5% of applied. Concentrations of metabolite B
increased throughout the study (MRID 41471009).
In an anaerobic aquatic metabolism study, vinclozolin degraded with a half-life of 134 days. 3,5-
DCA and Metabolite B were observed in this study as major degradates, with a maximum of
10.5% and 57% of applied, respectively. Metabolites E and S were also observed in this study as
minor degradates. When considering the persistence of vinclozolin residues of concern
(vinclozolin + metabolites B , E, F + 3,5-DCA), the anaerobic aquatic metabolism half-life of
these residues is 630 d. Given that concentrations of 3,5-DCA increased throughout the study,
the 371 d study was not of sufficient duration to capture the full formation and decline of 3,5-
DCA (MRIDs 43013002 and 43255801).
Volatilization
In a laboratory volatility study, a maximum of 7.1% of applied vinclozolin residues volatilized
from sand over a 30 day period. This corresponded to a flux rate that ranged between 0.00159-
0.0450 |ig/cm2*h (0.00341-0.0964 lb/A*d) for a 6 Ib a.i./A application (which is higher than the
currently allowed maximum application rate). The majority of volatile residues were identified
as vinclozolin, with some residues identified as metabolites B and E (MRID 42513101). For a
1.35 Ib a.i./A application, which is the maximum single application of vinclozolin relevant to
CA, the corresponding flux rate would be 0.000767-0.0217 lb/A*d.
Based on this information, in combination with the vapor pressure and Henry's law constants of
3,5-DCA (Table 4), volatilization represents a potential transport pathway of vinclozolin residues
of concern.
Sorption
Batch equilibrium studies indicate that vinclozolin, 3,5-DCA and metabolite E are moderately
mobile in soil (according to the FAO classification scheme for Koc) (Table 5).
Table 5. K,,c data for vinclozolin, 3,5-DCA and metabolite E in different soils.
Soil
Sand
Sandy loam
Silt Loam
Loam
Loamy sand
Clay loam
Clay
Mean
Vinclozolin
(MRID 41471010)
396
735
NA
535
NA
476
NA
536
Metabolite E
(MRID 41888904)
562
239
NA
260
NA
611
NA
418
3,5-DCA
(MRID 41888904)
496
356
NA
408
NA
908
NA
542
(MRID 45114101)
NA
593
380
NA
626
NA
932
633
NA = not available
21
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In sand, sandy loam, loam and clay loam soils, Koc values for vinclozolin were: 396 (Freundlich
Kd = 0.46, 1/n = 0.76), 735 (Kd = 3.82, 1/n = 0.99), 535 (Kd = 3.4, 1/n = 0.92), and 476 (Kd =
5.27, 1/n = 0.82), respectively (MRID 41471010). Kd values for vinclozolin correlated with soil
organic matter content (R2 = 0.90), indicating that Koc is a representative measure of the soil
partitioning of vinclozolin.
For Metabolite E, Koc values were: 562 (Kd = 0.65, 1/n = 0.98), 239 (Kd = 1.24, 1/n = 0.84), 260
(Kd = 1.66, 1/n = 0.78) and 611 (Kd = 6.73, 1/n = 0.80) in sand, sandy loam, loam and clay loam
soils, respectively (MRID 41888904). Kd values for metabolite E correlated with soil organic
matter content (R2 = 0.82), indicating that Koc is a representative measure of the soil partitioning
of metabolite E.
For 3,5-DCA, Koc values were: 496 (Kd = 0.58, 1/n = 0.74), 356(Kd = 1.86, 1/n = 0.82), 408 (Kd
= 2.60, 1/n = 0.79) and 908 (Kd = 10.0, 1/n = 0.76) in sand, sandy loam, loam and clay loam
soils, respectively (MRID 41888904). In an additional batch sorption study with 3,5-DCA, Koc
values were: 593 (Kd = 1.75, 1/n = 0.68), 626 (Kd = 7.17, 1/n = 0.634), 380 (Kd = 10.98, 1/n =
0.692) and 932 (Kd = 9.17, 1/n = 0.743) in sandy loam, loamy sand, silt loam and clay soils,
respectively (MRID 45114101). Kd values for 3,5-DCA correlated with soil organic matter
content (R2 = 0.78), indicating that Koc is a representative measure of the soil partitioning of 3,5-
DCA.
Based on this information, vinclozolin and its residues of concern have the potential to be
transported from treatment sites through runoff to surface waters or leaching to ground water.
Bioaccumulation
In a bioconcentration study with bluegill sunfish, total radioactive residues of vinclozolin
concentrated in fish tissues at a factor of 241X for whole fish. After a 14-day depuration period,
total radioactive residues declined 97.7% (from maximum). Metabolite F was reported as a
major degradate, representing as much as 24.7% and 9.3% of total radioactivity in edible and
non-edible tissues, respectively (MRID 136387). In a second bioconcentration study with
bluegill sunfish, total radioactive residues of vinclozolin concentrated in fish tissues at a factor of
279X for whole fish. 3,5-DCA and Metabolites B and S were observed in fish tissues. In the
edible tissues, 6.9-17.1% of radioactivity was not identified. In the non-edible tissues, 27.5-
34.5% of radioactivity was not identified (MRID 42847001). This leads to uncertainty in the
identification and relative proportions of the vinclozolin degradates present in the fish.
The octanol-water partition coefficient (1054) along with the submitted BCF studies indicate that
vinclozolin is not likely to bioaccumulate significantly in aquatic ecosystems.
Terrestrial Field Dissipation Studies
Four terrestrial field dissipation studies on multiple crops and locations are available for
vinclozolin (MRIDs 41538301, 42687601, 42717401 and 43505907). In acceptable terrestrial
field dissipation studies conducted in FL, NY, MO, and CA, vinclozolin dissipated with half-
lives of 34 to 94 days. Half-lives for total residues (vinclozolin plus its dichloroaniline-
22
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containing metabolites) were 179 to >1000 days. Dissipation half-lives of >2500 days for total
residues were reported for bare ground and turf studies in MO and NY. Persistence of total
residues appeared to be attributable to the resistance of 3,5-DCA to degradation and to the
inclusion of soil-bound residues in the data. Intermittent detections of residues were reported at
soil depths of 12-18, 18-24, and 24-30 inches. 3,5-DCA was detected regularly deeper than 6
inches. Residues may accumulate and be available for rotational crop uptake.
2.4.2 Mechanism of Action
Vinclozolin is a member of the carboximide fungicides used to control various blights and rots
caused by fungal pathogens. In mammals, the principal toxic effects induced by vinclozolin
and/or its metabolites are related to its antiandrogenic activity and its ability to act as a
competitive antagonist at the androgen receptor (USEPA 2000). According to the RED, there is
evidence that vinclozolin binds fairly weakly to the androgen receptor but that at least two
vinclozolin metabolites (B and E) occurring in mammals, plants, and soil are responsible for
much of the antiandrogenic activity attributed to vinclozolin.
2.4.3 Use Characterization
Analysis of labeled use information is the critical first step in evaluating the federal action. The
current label for vinclozolin represents the FIFRA regulatory action; therefore, labeled use and
application rates specified on the label form the basis of this assessment. The assessment of use
information is critical to the development of the action area and selection of appropriate
modeling scenarios and inputs.
Vinclozolin labels may be categorized into two types: labels for manufacturing uses (including
technical grade vinclozolin and its formulated products) and end-use products. While technical
products, which contain vinclozolin of high purity, are not used directly in the environment, they
are used to make formulated products, which can be applied in specific areas to control fungal
blights and rusts. The formulated product labels legally limit vinclozolin's potential use to only
those sites that are specified on the labels.
Currently, vinclozolin has two registered formulated products (registration #s: 7969-85 and
7969-224). Registration #7969-85 (Ronilan® EG fungicide) allows for vinclozolin use on canola
in the U.S., with the exception of California and Florida. Therefore, use of vinclozolin on canola
is not considered relevant to this assessment. Registration # 7969-224 (Curalan® EG fungicide)
allows for vinclozolin use on turf grass in the U.S. Since there are no prohibitions of use in
California on the label for Curalan® EG fungicide, use of vinclozolin on turf grass is considered
relevant to this assessment.
Curalan® EG fungicide is formulated as a 50% extruded granule (EG) sold only in water-soluble
packets. This product label indicates that it should be used as a preventative treatment. The
label indicates that single applications of vinclozolin should be made at 1.35 Ibs a.i./A with
intervals of 10-28 days (the specific interval depends upon the disease being treated).
According to the Use Verification Memo (Appendix A) issued by the EPA Office of Pesticide
Programs (OPP) Pesticide Reregi strati on Division (formerly known as the Special Review and
23
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Reregi strati on Division (SRRD)), the maximum number of applications per year is three (3).
The label indicates that the product be applied at a maximum seasonal rate of 4 Ibs a.i./A, and
with a maximum of 3 applications per season, this is equivalent to 3 applications of 1.35 Ibs
a.i./A. Applications are made by ground spray. The label prohibits applications by air and by
chemigation. The label also prohibits applications to residential turf. According to the Use
Verification Memo (Appendix A), the technical registrant (BASF) restricted the area of the golf
course to which product can applied to tee boxes, greens, and turf mowed at 1" or less.
Additionally, sod was restricted to sod produced for golf course landscape only.
Figure 2 depicts total vinclozolin use in California from 1997 to 2007 and indicates that from
2006 - 2007, total use averaged 390 Ibs based on California Pesticide Use Reports1 (PUR).
Compared to the peak use of 52,731 Ibs reported for 1998, vinclozolin use in California has
declined by roughly 99%. Where total acreage treated in 1998 was 69,067 acres, the acreage
treated had declined to 258 acres in 2007 representing a 99.6% decline. This can be attributed to
mitigation imposed by the 2000 RED with the majority of uses phased-out by 2004 (including
use of lettuce that was ended in 2005). According to the California PUR use report in 2007, of
the total pounds of vinclozolin applied, 82% was used in landscape maintenance. Of the
remaining amount, the majority was used on ornamental flowers and plants in greenhouses and
outdoors; approximately 4% was reportedly applied to peaches. If only use of vinclozolin in CA
on "landscape maintenance" (assumed to be a surrogate for applications to turf grass) is
considered from 1999 to 2006, applications ranged 289 to as high as 1898 Ibs in a single year
(Figure 3). This corresponds to an annual average of 709 Ibs.
The uses considered in this risk assessment represent all currently registered uses according to a
review of all current labels, relevant to the CRLF. No other uses are relevant to this assessment.
Any reported use other than currently registered uses represent either historic uses that have been
canceled, mis-reported uses, or mis-use. Historic uses, mis-reported uses, and misuse are not
considered part of the federal action and, therefore, are not considered in this assessment.
1 California Department of Pesticide Regulation. 2007. Summary of Pesticide Use Report Date 2007 Indexed by
Chemical, http://www.cdpr.ca.gov/docs/pur/pur07rep/chmrpt07.pdf
24
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60000
re
10000
1997 1999 2001 v 2003 2005 2007
Year
Figure 2. Total annual use of vinclozolin in California between 1996 - 2007. California
Department of Pesticide Regulation.
2,000 -,
1 800 -
o
Q. 1 BOO -
o
to
T3 1 400
oj
•8 S
-------
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 I.
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 4). Recovery
units, core areas, and other known occurrences of the CRLF from the CNDDB are described in
further detail in Attachment I, and designated critical habitat is addressed in Section 2.6.
Recovery units are large areas defined at the watershed level that have similar conservation
needs and management strategies. The recovery unit is primarily an administrative designation,
and land area within the recovery unit boundary is not exclusively CRLF habitat. Core areas are
smaller areas within the recovery units that comprise portions of the species' historic and current
range and have been determined by 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
26
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the current range of the species not included in core areas and/or designated critical habitat, but
within the recovery units.
Other Known Occurrences from the CNDBB
The CNDDB provides location and natural history information on species found in California.
The CNDDB serves as a repository for historical and current species location sightings.
Information regarding known occurrences of CRLFs outside of the currently occupied core areas
and designated critical habitat is considered in defining the current range of the CRLF. See:
http://www.dfg.ca.gov/bdb/html/cnddb info.html for additional information on the CNDDB.
27
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Recovery Units
1. Sierra Nevada Foothills and Central Valley
2. North Coast Range Foothills and Western
Sacramento River Valley
3. North Coast and North San Francisco Bay
4. South and East San Francisco Bay
5. Central Coast
Diablo Range and Salinas Valley
Northern Transverse Ranges and Tehachapi
Mountains
Southern Transverse and Peninsular Ranges
Legend
] Recovery Unit Boundaries
\\ Currently Occupied Core Areas
^B Critical Habitat
BH CNDDB Occurence Sections
County Boundaries g
45
Core Areas
1. Feather River
2. Yuba River- S. Fork Feather River
3. Traverse Creek/ Middle Fork/ American R. Rubicon
4. Cosumnes River
5. South Fork Calaveras River*
6. Tuolumne River*
7. Piney Creek*
8. Cottonwood Creek
9. Putah Creek - Cache Creek*
10. Lake Berryessa Tributaries
11. Upper Sonoma Creek
12. Petaluma Creek — Sonoma Creek
13. Ft. Reyes Peninsula
14. Belvedere Lagoon
15. Jameson Canyon - Lower Napa River
16. East San Francisco Bay
17. Santa Clara Valley
18. South San Francisco Bay
* Core areas that were historically occupied by the California red
19. Watsonville Slough-Elkhorn Slough
20. Carmel River — Santa Lucia
21. Gab Ian Range
22. Estero Bay
23. Arroyo Grange River
24. Santa Maria River - Santa Ynez River
25. Sisquoc River
26. Ventura River - Santa Clara River
27. Santa Monica Bay - Venura Coastal Streams
28. Estrella River
29. San Gabriel Mountain*
30. Forks of the Mojave*
31. Santa Ana Mountain*
32. Santa Rosa Plateau
33. San Luis Ray*
34. Sweetwater*
35. Laguna Mountain*
-legged frog are not included in the map
Figure 4. Recovery Unit, Core Area, Critical Habitat, and Occurrence Designations for CRLF.
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2.5.2 Reproduction
CRLFs breed primarily in ponds; however, they may also breed in quiescent streams, marshes,
and lagoons (Fellers 2005a). According to the Recovery Plan (USFWS 2002), CRLFs breed
from November through late April. Peaks in spawning activity vary geographically; Fellers
(2005b) reports peak spawning as early as January in parts of coastal central California. Eggs
are fertilized as they are being laid. Egg masses are typically attached to emergent vegetation,
such as bulrushes (Scirpus spp.) and cattails (Typha spp.) or roots and twigs, and float on or near
the surface of the water (Hayes and Miyamoto 1984). Egg masses contain approximately 2000
to 6000 eggs ranging in size between 2 and 2.8 mm (Jennings and Hayes 1994). Embryos hatch
10 to 14 days after fertilization (Fellers 2005a) depending on water temperature. Egg predation
is reported to be infrequent and most mortality is associated with the larval stage (particularly
through predation by fish); however, predation on eggs by newts has also been reported
(Rathburn 1998). Tadpoles require 11 to 28 weeks to metamorphose into juveniles (terrestrial-
phase), typically between May and September (Jennings and Hayes 1994, USFWS 2002);
tadpoles have been observed to over-winter (delay metamorphosis until the following year)
(Fellers 2005b, USFWS 2002). Males reach sexual maturity at 2 years, and females reach sexual
maturity at 3 years of age; adults have been reported to live 8 to 10 years (USFWS 2002). Figure
5 depicts CRLF annual reproductive timing.
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 = Young Juveniles
Adults and juveniles can be present all year
Figure 5. CRLF Reproductive Events by Month.
2.5.3
Diet
Although the diet of CRLF aquatic-phase larvae (tadpoles) has not been studied specifically, it is
assumed that their diet is similar to that of other frog species, with the aquatic phase feeding
exclusively in water and consuming diatoms, algae, and detritus (USFWS 2002). Tadpoles filter
and entrap suspended algae (Seale and Beckvar, 1980) via mouthparts designed for effective
grazing of periphyton (Wassersug, 1984, Kupferberg et al.\ 1994; Kupferberg, 1997; Altig and
McDiarmid, 1999).
Juvenile and adult CRLFs forage in aquatic and terrestrial habitats, and their diet differs greatly
from that of larvae. The main food source for juvenile aquatic- and terrestrial-phase CRLFs is
thought to be aquatic and terrestrial invertebrates found along the shoreline and on the water
surface. Hayes and Tennant (1985) report, based on a study examining the gut content of 35
juvenile and adult CRLFs, that the species feeds on as many as 42 different invertebrate taxa,
including Arachnida, Amphipoda, Isopoda, Insecta, and Mollusca. The most commonly observed
29
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prey species were larval alderflies (Sialis cf. califomica), 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 foraging quality
of the riparian habitat depends on moisture, composition of the plant community, and presence of
pools and backwater aquatic areas for breeding. CRLFs can be found living within streams at
distances up to 3 km (2 miles) from their breeding site and have been found up to 30 m (100 feet)
from water in dense riparian vegetation for up to 77 days (USFWS 2002).
During dry periods, the CRLF is rarely found far from water, although it will sometimes disperse
from its breeding habitat to forage and seek other suitable habitat under downed trees or logs,
industrial debris, and agricultural features (UWFWS 2002). According to Jennings and Hayes
(1994), CRLFs also use small mammal burrows and moist leaf litter as habitat. In addition,
CRLFs may also use large cracks in the bottom of dried ponds as refugia; these cracks may
provide moisture for individuals avoiding predation and solar exposure (Alvarez 2000).
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2.6 Designated Critical Habitat
In a final rule published on April 13, 2006, 34 separate units of critical habitat were designated
for the CRLF by USFWS (USFWS 2006; FR 51 19244-19346). A summary of the 34 critical
habitat units relative to USFWS-designated recovery units and core areas (previously discussed
in Section 2.5.1) is provided in Attachment I.
'Critical habitat' is defined in the ESA as the geographic area occupied by the species at the time
of the listing where the physical and biological features necessary for the conservation of the
species exist, and there is a need for special management to protect the listed species. It may
also include areas outside the occupied area at the time of listing if such areas are 'essential to
the conservation of the species.' All designated critical habitat for the CRLF was occupied at the
time of listing. Critical habitat receives protection under Section 7 of the ESA (Section 7)
through prohibition against destruction or adverse modification with regard to actions carried
out, funded, or authorized by a federal Agency. Section 7 requires consultation on federal
actions that are likely to result in the destruction or adverse modification of critical habitat.
To be included in a critical habitat designation, the habitat must be 'essential to the conservation
of the species.' Critical habitat designations identify, to the extent known using the best
scientific and commercial data available, habitat areas that provide essential life cycle needs of
the species or areas that contain certain primary constituent elements (PCEs) (as defined in 50
CFR 414.12(b)). PCEs include, but are not limited to, space for individual and population
growth and for normal behavior; food, water, air, light, minerals, or other nutritional or
physiological requirements; cover or shelter; sites for breeding, reproduction, rearing (or
development) of offspring; and habitats that are protected from disturbance or are representative
of the historic geographical and ecological distributions of a species. The designated critical
habitat areas for the CRLF are considered to have the following PCEs that justify critical habitat
designation:
• Breeding aquatic habitat;
• Non-breeding aquatic habitat;
• Upland habitat; and
• Dispersal habitat.
Further description of these habitat types is provided in Attachment I.
Occupied habitat may be included in the critical habitat only if essential features within the
habitat may require special management or protection. Therefore, 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,
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and to reduce the rate of conversion to other land uses that are incompatible with CRLF
conservation. Please see Attachment I for a full explanation on this special rule.
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 vinclozolin 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) Alteration of chemical characteristics necessary for normal growth and viability of
juvenile and adult CRLFs.
(3) Significant increase in sediment deposition within the stream channel or pond or
disturbance of upland foraging and dispersal habitat that could result in elimination or
reduction of habitat necessary for the growth and reproduction of the CRLF by
increasing the sediment deposition to levels that would adversely affect their ability to
complete their life cycles.
(4) Significant alteration of channel/pond morphology or geometry that may lead to changes
to the hydrologic functioning of the stream or pond and alter the timing, duration, water
flows, and levels that would degrade or eliminate the CRLF and/or its habitat. Such an
effect could also lead to increased sedimentation and degradation in water quality to
levels that are beyond the CRLF's tolerances.
(5) Elimination of upland foraging and/or aestivating habitat or dispersal habitat.
(6) Introduction, spread, or augmentation of non-native aquatic species in stream segments
or ponds used by the CRLF.
(7) Alteration or elimination of the CRLF's food sources or prey base (also evaluated as
indirect effects to the CRLF).
As previously noted in Section 2.1, the Agency believes that the analysis of direct and indirect
effects to listed species provides the basis for an analysis of potential effects on the designated
critical habitat. Because vinclozolin is expected to directly impact living organisms within the
action area, critical habitat analysis for vinclozolin 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 vinclozolin is likely to encompass considerable portions of the United States based on the use
of vinclozolin on turf grass and canola (outside of California). However, the scope of this
assessment limits consideration of the overall action area to those portions that may be applicable
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to the protection of the CRLF and its designated critical habitat within the state of California.
The Agency's approach to defining the action area under the provisions of the Overview
Document (USEPA 2004) considers the results of the risk assessment process to establish
boundaries for that action area with the understanding that exposures below the Agency's
defined Levels of Concern (LOCs) constitute a no-effect threshold. For the purposes of this
assessment, attention will be focused on the footprint of the action (i.e., the area where pesticide
application occurs), plus all areas where offsite transport (i.e., spray drift, downstream dilution,
etc.) may result in potential exposure within the state of California that exceeds the Agency's
LOCs.
Deriving the geographical extent of this portion of the action area is based on consideration of
the types of effects that vinclozolin may be expected to have on the environment, the exposure
levels to vinclozolin that are associated with those effects, and the best available information
concerning the use of vinclozolin and its fate and transport within the state of California.
Specific measures of ecological effect for the CRLF that define the action area include any direct
and indirect toxic effect to the CRLF and any potential modification of its critical habitat,
including reduction in survival, growth, and fecundity as well as the full suite of sublethal effects
available in the effects literature. Therefore, the action area extends to a point where
environmental exposures are below any measured lethal or sublethal effect threshold for any
biological entity at the whole organism, organ, tissue, and cellular level of organization. In
situations where it is not possible to determine the threshold for an observed effect, the action
area is not spatially limited and is assumed to be the entire state of California.
The definition of action area requires a stepwise approach that begins with an understanding of
the federal action. The federal action is defined by the currently labeled uses for vinclozolin. An
analysis of labeled uses and review of available product labels was completed (see section 2.4.3).
Use of vinclozolin on canola is permitted in the United States; however, since this use is
prohibited in California (and also in Florida), it is not considered part of the federal action. For
those uses relevant to the CRLF, the analysis indicates that, for vinclozolin, the following use is
considered as part of the federal action evaluated in this assessment: turf grass (for golf courses
and industrial park landscapes; this does not include residential areas).
Following a determination of the assessed uses, an evaluation of the potential "footprint" of
vinclozolin use patterns (i.e., the area where pesticide application occurs) is usually determined.
This "footprint" represents the initial area of concern, based on an analysis of available land
cover data for the state of California. As indicated above, the federal action assessed here is the
use of vinclozolin on golf course and industrial park landscape turf grass. Vinclozolin use is
prohibited on residential turf. Available turf grass landcovers include residential areas; therefore,
a landcover map representative of the footprint for vinclozolin cannot be derived.
In place of this initial footprint, an analysis of the pesticide use data for vinclozolin can provide
useful information of where vinclozolin has been used in the past. From 1999-2006, vinclozolin
was used in 26 counties in CA for "landscape maintenance." Several of these counties
(Alameda, Butte, Contra Costa, Los Angeles, Marin, Merced, Monterey, Orange, Riverside,
Sacramento, San Diego, San Joaquin, San Luis Obispo, San Mateo, Santa Barbara, Santa Clara,
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Santa Cruz, Solano, Sonoma, Stanislaus, and Ventura) include core areas and critical habitat of
the CRLF.
Once the initial area of concern is defined, the next step is to define the potential boundaries of
the action area by determining the extent of offsite transport via spray drift and runoff where
exposure of one or more taxonomic groups to the pesticide exceeds the listed species LOCs. In
this assessment, transport of vinclozolin through runoff and spray drift is considered in deriving
quantitative estimates of vinclozolin 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 vinclozolin at concentrations above the Agency's Levels of Concern (LOG), there is need
to expand the action area to include areas that are affected indirectly by this federal action.
Because vinclozolin was classified as a Group C chemical (possible human carcinogen) and the
terminal metabolite of vinclozolin, 3,5-DCA was considered to have a genotoxic mode of tumor
induction (based on its similarity to its structural analog parachloraniline which is carcinogenic
in mammals), the action area for vinclozolin is established as the entire state of California.
2.8 Assessment Endpoints and Measures of Ecological Effect
Assessment endpoints are defined as "explicit expressions of the actual environmental value that
is to be protected."2 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 vinclozolin (e.g., runoff, spray drift, etc.), and the
routes by which ecological receptors are exposed to vinclozolin (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. It
should be noted that assessment endpoints are limited to direct and indirect effects associated
with survival, growth, and fecundity, and do not include the full suite of sublethal effects used to
define the action area. According the Overview Document (USEPA 2004), the Agency relies on
acute and chronic effects endpoints that are either direct measures of impairment of survival,
growth, or fecundity or endpoints for which there is a scientifically robust, peer reviewed
relationship that can quantify the impact of the measured effect endpoint on the assessment
endpoints of survival, growth, and fecundity.
!U.S. EPA (1992). Framework for Ecological Risk Assessment. EPA/630/R-92/001.
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A discussion of all the toxicity data available for this risk assessment, including resulting
measures of ecological effect selected for each taxonomic group of concern, is included in
Section 4.0 of this document. A summary of the assessment endpoints and measures of
ecological effect selected to characterize potential assessed direct and indirect CRLF risks
associated with exposure to vinclozolin is provided in Table 6.
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Table 6. Assessment Endpoints and Measures of Ecological Effects.
Assessment Endpoint
Measures of Ecological Effects
Aquatic-Phase CRLF (Eggs, larvae, juveniles, and adults)3
Direct Effects
1. Survival, growth, and reproduction of
CRLF
la. Rainbow trout (Oncorhynchus mykiss) 96-hr LCso, i.e., the
most sensitive acute exposure data available for fish
Ib. Fathead minnow (Pimephales promelas) NOAEC, i.e., the
most sensitive chronic exposure data available for fish
Indirect Effects and Critical Habitat Effects
1. Survival, growth, and reproduction of
CRLF individuals via indirect effects on
aquatic prey food supply (i.e., fish,
freshwater invertebrates, non-vascular plants)
3. Survival, growth, and reproduction of
CRLF individuals via indirect effects on
habitat, cover, food supply, and/or primary
productivity (i.e., aquatic plant community)
4. Survival, growth, and reproduction of
CRLF individuals via effects to riparian
vegetation
2a. Waterflea (Daphnia magna) EC50, i.e., most sensitive acute
exposure data available for aquatic invertebrates
2b. Waterflea NOAEC, i.e., most sensitive chronic exposure
data available for aquatic invertebrates
2c. Rainbow trout LC50, based on most sensitive acute exposure
data available for fish
2d. Fathead minnow NOAEC, based on most sensitive chronic
exposure data available for fish
2e. EC50, based on available data for freshwater diatom
Navicula pelliculosa.
3a. EC50 based on most sensitive vascular plant, /'. e. , duckweed
(Lemna gibba).
3b. EC50 based on available data for freshwater diatom Navicula
pelliculosa.
No data are available to quantify an endpoint to represent effects
of vinclozolin exposures to terrestrial plants.
Terrestrial-Phase CRLF (Juveniles and adults)
Direct Effects
5. Survival, growth, and reproduction of
CRLF individuals via direct effects on
terrestrial phase adults and juveniles
5a. Northern bobwhite quail (Colinus virginianus) LD50, based
on most sensitive acute oral exposure data available for birds2
5b. Northern bobwhite quail LC50, based on most sensitive
subacute dietary exposure data available for birds2
5c. Northern bobwhite quail NOAEC, based on most sensitive
chronic exposure data available for birds2
Indirect Effects and Critical Habitat Effects
6. Survival, growth, and reproduction of
CRLF individuals via effects on terrestrial
prey (i.e., terrestrial invertebrates, small
mammals , and frogs)
7. Survival, growth, and reproduction of
CRLF individuals via indirect effects on
habitat (i.e., riparian and upland vegetation)
6a. Honeybee (Apis melliferd) LD50, based on most sensitive
acute contact exposure data available for terrestrial
invertebrates.
6b. Laboratory rat (Rattus norvegicus) LD50, based on most
sensitive acute oral exposure data available for mammals
6c. Laboratory rat NOAEC, based on most sensitive chronic
exposure data available for mammals
6d. Northern bobwhite quail LD50, based on most sensitive
acute oral exposure data available for birds2
6e. Northern bobwhite quail LC50, based on most sensitive
subacute dietary exposure data available for birds2
6f. Northern bobwhite quail NOAEC, based on most sensitive
chronic exposure data available for birds2
No data are available to quantify an endpoint to represent effects
of vinclozolin exposures to terrestrial plants.
" 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.
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2.8.2 Assessment Endpoints for Designated Critical Habitat
As previously discussed, designated critical habitat is assessed to evaluate actions related to the
use of vinclozolin that may alter the PCEs of the CRLF's critical habitat. PCEs for the CRLF
were previously described in Section 2.6. Actions that may modify critical habitat are those that
alter the PCEs and jeopardize the continued existence of the CRLF. Therefore, these actions are
identified as assessment endpoints. It should be noted that evaluation of PCEs as assessment
endpoints is limited to those of a biological nature (i.e., the biological resource requirements for
the listed species associated with the critical habitat) and those for which vinclozolin effects data
are available. Adverse modification to the critical habitat of the CRLF includes, but is not
limited to, those listed in Section 2.6.
Measures of such possible effects by labeled use of vinclozolin on critical habitat of the CRLF
are described in Table 7. 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 7. Summary of Assessment Endpoints and Measures of Ecological Effect for Primary
Constituent Elements of Designated Critical Habitat3.
Assessment Endpoint
Measures of Ecological Effect
Aquatic-Phase CRLFPCEs
(Aquatic Breeding Habitat and Aquatic Non-Breeding Habitat)
Alteration of channel/pond morphology or geometry
and/or increase in sediment deposition within the
stream channel or pond: aquatic habitat (including
riparian vegetation) provides for shelter, foraging,
predator avoidance, and aquatic dispersal for juvenile
and adult CRLFs.
Alteration in water chemistry /quality including
temperature, turbidity, and oxygen content necessary
for normal growth and viability of juvenile and adult
CRLFs and their food source.
Alteration of other chemical characteristics necessary
for normal growth and viability of CRLFs and their
food source.
Reduction and/or modification of aquatic-based food
sources for pre-metamorphs (e.g., algae)
3a. Duckweed EC50, based on most sensitive vascular plant
3b. N. pelliculosa ECso based on most sensitive non-
vascular plant (freshwater diatom)
No data are available to quantify an endpoint to represent
effects of vinclozolin exposures to terrestrial plants.
N. pelliculosa EC50, based on most sensitive non-vascular
plant (freshwater diatom)
No data are available to quantify an endpoint to represent
effects of vinclozolin exposures to terrestrial plants.
LC50 = 2.84 mg/L, based on most sensitive acute exposure
data available for fish
EC50 = 4.0 mg/L, based on most sensitive acute exposure
data available for aquatic invertebrates
Fathead minnow NOAEC, based on most sensitive chronic
exposure data available for fish
Waterflea NOAEC, based on most sensitive chronic
exposure data available for aquatic invertebrates
Duckweed EC50, based on most sensitive vascular plant
N. pelliculosa EC50, based on most sensitive non-vascular
plant (freshwater diatom)
Terrestrial-Phase CRLFPCEs
(Upland Habitat and Dispersal Habitat)
Elimination and/or disturbance of upland habitat;
ability of habitat to support food source of CRLFs:
Upland areas within 200 ft of the edge of the riparian
vegetation or dripline surrounding aquatic and riparian
habitat that are comprised of grasslands, woodlands,
and/or wetland/riparian plant species that provides the
CRLF shelter, forage, and predator avoidance
Elimination and/or disturbance of dispersal habitat:
Upland or riparian dispersal habitat within designated
units and between occupied locations within 0.7 mi of
each other that allow for movement between sites
including both natural and altered sites which do not
contain barriers to dispersal
Reduction and/or modification of food sources for
terrestrial phase juveniles and adults
Alteration of chemical characteristics necessary for
normal growth and viability of juvenile and adult
CRLFs and their food source.
No data are available to quantify an endpoint to represent
effects of vinclozolin exposures to terrestrial plants.
Honeybee LD50, based on most sensitive acute exposure
data available for terrestrial invertebrates
Laboratory rat LD50, based on most sensitive acute oral
exposure data available for mammals
Laboratory rat NOAEL, based on most sensitive chronic
exposure data available for mammals
Northern bobwhite quail LD50, based on most sensitive
acute oral exposure data available for birds2
Northern bobwhite quail LC50, based on most sensitive
subacute dietary exposure data available for birds2
Northern bobwhite quail NOAEC, based on most sensitive
chronic exposure data available for birds2
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 (U.S. EPA, 1998). For this assessment, the risk is stressor-linked,
where the stressor is the release of vinclozolin to the environment. The following risk
hypotheses are presumed for this endangered species assessment.
The labeled use of vinclozolin 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 vinclozolin release mechanisms, biological receptor types, and effects endpoints of
potential concern. The conceptual models for terrestrial and aquatic exposures are shown in
Figure 6 and Figure 7, respectively, which include the conceptual models for the aquatic and
terrestrial PCE components of critical habitat.
39
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Stressor
Source
Exposure
Media
Vinclozolin residues of concern
1
1
\ Spray drift
* *—Dermal uptake/lnaestiorr*—
| Runoff |
Terrestrial-phase
amphibians
Terrestrial/riparian plants
grasses/forbs, fruit, seeds
(trees, shrubs)
Volatilization
Root uptake^]
Ingestion
Receptors
Ingestion
Birds/terrestrial-
phase amphibians/
reptiles/mammals
Attribute
Change
1.
Individual
organisms
Reduced survival
Reduced growth
Reduced reproduction
Wet/drv deposition*''
Food chain
Reduction in prey
Modification of PCEs
related to prey availability
Habitat integrity
Reduction in primary productivity
Reduced cover
ommunity change
Modification of PCEs related to
habitat
Figure 6. Conceptual Model for Vinclozolin Effects on Terrestrial Phase of the CRLF.
40
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Stressor
Source
Exposure
Media
Vinclozolin residues of concern
1 1
^
| Spray drift | | Runoff
Groundwater] I Volatilization!
Surface water/
Sediment
\
T
.Wet/dry deposition.
Receptors
Uptake/gills
or integument
Uptake/gills
or integument
Aquatic Animals
Invertebrates
Vertebrates
Fish/aquatic-phase
amphibians
Inqe^tion
Attribute Individual
Change
organisms
Reduced survival
Reduced growth
Reduced reproduction
Uptake/cell,
roots^ leaves
Aquatic Plants
Non-vascular
Vascular
t
Inqestion
Food chain
Reduction in algae
Reduction in prey
Modification of PCEs
related to prey availability
1
Riparian plants
terrestrial
exposure
pathways see
Figure 6
Habitat integrity
Reduction in primary
oroductivity
Reduced cover
ommunity change
Modification of PCEs related to
habitat
Figure 7. Conceptual Model for Vinclozolin Effects on Aquatic Phase of the CRLF.
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 vinclozolin are characterized and integrated to assess the risks. This is
accomplished using a risk quotient (ratio of exposure concentration to effects concentration)
approach. Although risk is often defined as the likelihood and magnitude of adverse ecological
effects, the risk quotient-based approach does not provide a quantitative estimate of likelihood
and/or magnitude of an adverse effect. However, as outlined in the Overview Document (U.S.
EPA, 2004), the likelihood of effects to individual organisms from particular uses of vinclozolin
is estimated using the probit dose-response slope and either the level of concern (discussed
below) or actual calculated risk quotient value.
41
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2.10.1 Measures to Evaluate the Risk Hypothesis and Conceptual Model
2.10.1.1 Measures of Exposure
The environmental fate properties of vinclozolin indicate that runoff and spray drift are the
principle potential transport mechanisms of vinclozolin to the aquatic and terrestrial habitats of
the CRLF. In this assessment, transport of vinclozolin through runoff and spray drift is
considered in deriving quantitative estimates of vinclozolin 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 vinclozolin and residues of concern 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 Model System
(PRZM/EXAMS). The model used to predict terrestrial EECs on food items is T-REX. These
models are parameterized using relevant reviewed registrant-submitted environmental fate data.
PRZM (V3.12.2, May 2005) and EXAMS (V2.98.4.6, April 2005) are screening simulation
models coupled with the input shell pe5.pl (Aug 2007) to generate daily exposures and l-in-10
year EECs of vinclozolin residue that may occur in surface water bodies adjacent to application
sites receiving loading 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
vinclozolin. 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 (version 1.4.1, 06/21/2008). 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 vinclozolin 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 largest
42
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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 vinclozolin are bound by
using the dietary based EECs for small insects and large insects.
Birds are currently used as surrogates for terrestrial-phase CRLF. However, amphibians are
poikilotherms (body temperature varies with environmental temperature) while birds are
homeotherms (temperature is regulated, constant, and largely independent of environmental
temperatures). Therefore, amphibians tend to have much lower metabolic rates and lower caloric
intake requirements than birds or mammals. As a consequence, birds are likely to consume more
food than amphibians on a daily dietary intake basis, assuming similar caloric content of the food
items. Therefore, the use of avian food intake allometric equation as a surrogate to amphibians is
likely to result in an over-estimation of exposure and risk for reptiles and terrestrial-phase
amphibians. Therefore, T-REX (version 1.4.1) has been refined to the T-HERPS model (v. 1.0),
which allows for an estimation of food intake for poikilotherms using the same basic procedure
as T-REX to estimate avian food intake.
The spray drift model, AgDRIFT is used to assess exposures of terrestrial phase CRLF and its
prey to vinclozolin deposited on terrestrial habitats by spray drift. In addition to the buffered
area from the spray drift analysis, the downstream extent of vinclozolin that exceeds the LOG for
the effects determination is also considered.
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 (USEPA 2009). The ECOTOXicology database (ECOTOX) was searched in order
to provide more ecological effects data and in an attempt to bridge existing data gaps. ECOTOX
is a source for locating single chemical toxicity data for aquatic life, terrestrial plants, and
wildlife. ECOTOX was created and is maintained by the USEPA, Office of Research and
Development, and the National Health and Environmental Effects Research Laboratory's Mid-
Continent Ecology Division.
The assessment of risk for direct effects to the terrestrial-phase CRLF makes the assumption that
toxicity of vinclozolin 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,
LCso and ECso. LD stands for "Lethal Dose", and LDso is the amount of a material, given all at
once, that is estimated to cause the death of 50% of the test organisms. LC stands for "Lethal
Concentration" and LCso is the concentration of a chemical that is estimated to kill 50% of the
test organisms. EC stands for "Effective Concentration" and the ECso is the concentration of a
chemical that is estimated to produce a specific effect in 50% of the test organisms. Endpoints
43
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for chronic measures of exposure for listed and non-listed animals are the NOAEL/NOAEC and
NOEC. NOAEL stands for "No Ob served-Adverse-Effect-Level" and refers to the highest tested
dose of a substance that has been reported to have no harmful (adverse) effects on test
organisms. The NOAEC {i.e.., "No-Observed-Adverse-Effect-Concentration") is the highest test
concentration at which none of the observed effects were statistically different from the control.
The NOEC is the No-Observed-Effects-Concentration. For non-listed plants, only acute
exposures are assessed (i.e., EC25 for terrestrial plants and ECso for aquatic plants).
It is important to note that the measures of effect for direct and indirect effects to the CRLF and
its designated critical habitat are associated with impacts to survival, growth, and fecundity, and
do not include the full suite of sublethal effects used to define the action area. According the
Overview Document (USEPA 2004), the Agency relies on effects endpoints that are either direct
measures of impairment of survival, growth, or fecundity or endpoints for which there is a
scientifically robust, peer reviewed relationship that can quantify the impact of the measured
effect endpoint on the assessment endpoints of survival, growth, and fecundity.
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 vinclozolin,
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 vinclozolin 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 B).
For this endangered species assessment, listed species LOCs are used for comparing RQ values
for acute and chronic exposures of vinclozolin directly to the CRLF. If estimated exposures
directly to the CRLF of vinclozolin resulting from a particular use are sufficient to exceed the
listed species LOG, then the effects determination for that use is "may affect". When
considering indirect effects to the CRLF due to effects to animal prey (aquatic and terrestrial
invertebrates, fish, frogs, and mice), the listed species LOCs are also used. If estimated
exposures to CRLF prey of vinclozolin resulting from a particular use are sufficient to exceed the
listed species LOG, then the effects determination for that use is a "may affect." If the RQ being
considered also exceeds the non-listed species acute risk LOG, then the effects determination is a
LAA. If the acute RQ is between the listed species LOG and the non-listed acute risk species
LOG, then further lines of evidence (i.e. probability of individual effects, species sensitivity
distributions) are considered in distinguishing between a determination of NLAA and a LAA.
When considering indirect effects to the CRLF due to effects to algae as dietary items or plants
as habitat, the non-listed species LOG for plants is used because the CRLF does not have an
obligate relationship with any particular aquatic and/or terrestrial plant. If the RQ being
considered for a particular use exceeds the non-listed species LOG for plants, the effects
determination is "may affect". Further information on LOCs is provided in Appendix B.
44
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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
vinclozolin 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.
2.10.2 Data Gaps
At this time, there are no data available on the aerobic aquatic metabolism half-life for
vinclozolin. Thus the extent to which vinclozolin is subject to biotic degradation in aerobic
aquatic areas (e.g., the water column of a pond) is uncertain. However, given the rapid rate of
hydrolysis at environmentally relevant pHs, hydrolysis is expected to be the major degradation
process in aquatic environments.
Additionally, there are no acceptable terrestrial plant toxicity data for vinclozolin. Since the
ECso has not been definitively established for freshwater diatoms (N. pelliculosa), it too
represents a data gap.
There are also limited data available to characterize the environmental fate and effects of
vinclozolin's major degradates.
3.0 Exposure Assessment
3.1 Label Application Rates and Intervals
As indicated in Section 2.4.3 (use characterization), the only use of vinclozolin that is relevant to
California is applications to turf grass (specifically, golf courses and industrial park landscapes).
The label indicates that single applications of vinclozolin should be made at 1.35 Ibs a.i./A with
intervals of 10-28 days (the specific interval depends upon the disease being treated). According
to the Use Verification Memo (Appendix A), the maximum number of applications per year is
three (3). The label indicates that the product be applied at a maximum seasonal rate of 4 Ibs
45
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a.i./A, and with a maximum of 3 applications per season, this is equivalent to 3 applications of
1.35 Ibs a.i./A. Applications are made by ground spray. The label prohibits applications by air
and by chemigation. The label also prohibits applications to residential turf.
3.2 Surface Water Exposure Assessment
3.2.1 Modeling Approach
Aquatic exposures are quantitatively estimated (using PRZM/EXAMS) for all of assessed uses
using scenarios that represent high exposure sites for vinclozolin use. To model vinclozolin use
on turf grass, the CA turf scenario was selected.
Each PRZM scenario 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 large
drainage areas (or both). Shallow water bodies tend to have limited additional storage capacity,
and thus, tend to overflow and carry pesticide in the discharge whereas the standard pond has no
discharge. As watershed size increases beyond 10 hectares, at some point, it becomes unlikely
that the entire watershed is planted to a single crop, which is all treated with the pesticide.
Headwater streams can also have peak concentrations higher than the standard pond, but they
tend to persist for only short periods of time and are then carried downstream.
3.2.2 Model Inputs for Vinclozolin Residues of Concern
The appropriate chemical-specific PRZM input parameters are selected from reviewed physical,
chemical and environmental fate data submitted by the registrant (Table 3 and Table 4) and in
accordance with EFED water model input parameter selection guidance (U.S. EPA 2002). The
input parameters for relevant to the fate of vinclozolin residues of concern used in PRZM and
EXAMS are in Table 8. Outputs from PRZM/EXAMS are provided in Appendix C.
As noted in section 2.4.1, it is assumed that metabolites B, E, F and S are intermediate
metabolites between vinclozolin and its ultimate degradation product, 3,5-DCA. There is some
uncertainty associated with the half-lives obtained from the available laboratory degradation
studies with vinclozolin in that they were not necessarily of sufficient duration to capture the full
formation and decline of 3,5-DCA. Therefore, half-lives calculated using these laboratory studies
may under predict the half-lives of the vinclozolin total residues of concern. In order to provide a
conservative estimate of exposure of non-target aquatic organisms to vinclozolin total residues of
concern, it was assumed that these total residues were stable to degradation. Uncertainties
associated with this approach are further explored in section 6.
46
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Table 8. PRZM/EXAMS input parameters relevant to the fate of vinclozolin.
Input Parameter
Molecular Wt. (g/mol)
Henry's Law Constant
(atm-m3/mol)
Vapor pressure (torr)
Solubility in water
(mg/L @ pH 7, 20°C)
Hydrolysis half-life
(days)
Aqueous photolysis
half-life (days)
Aerobic Soil
Metabolism Half-life
(days)
Aerobic Aquatic
Metabolism Half-life
(days)
Anaerobic Aquatic
Metabolism Half-life
(days)
Koc (L/kgoc)
Value
286.11
3.8 xlO"7
2.6 x 10"6
2.6
0*
0*
0*
0*
0*
532
Comments
Value for vinclozolin; See Table 4.
Value for vinclozolin; See Table 4.
Value for vinclozolin; See Table 4.
Value for vinclozolin; See Table 4.
Vinclozolin residues of concern are stable to hydrolysis (MRID 41471006)
An aqueous photolysis half -life of 75.5 days can be derived to represent
vinclozolin + metabolites B and E. Given that concentrations of metabolite
E increased throughout the study, the 30 d study was not necessarily of
sufficient duration to capture the full formation and decline of metabolite E.
The study was also not of sufficient duration to capture the formation and
decline of 3,5-DCA, which was not detected during this study (MRID
42394706).
It is assumed that vinclozolin residues of concern are stable, based on an
aerobic soil metabolism study indicating that 3,5-DCA (vinclozolin' s
terminal degradate) is stable (MRID 45239201)
No data are available for this half-life. Input parameter guidance indicates
that in the case that a chemical is stable to hydrolysis, this parameter should
be defined as 2x the aerobic soil metabolism half -life used in PRZM (which
isO).
An anaerobic aquatic half -life of 630 days was derived to represent
vinclozolin + metabolites B , E, F + 3,5-DCA. Given that concentrations of
3,5-DCA increased throughout the study, the 371 d study was not
necessarily of sufficient duration to capture the full formation and decline of
3,5-DCA (MRID 43013002).
Mean of Koc values for vinclozolin, metabolite E and 3,5-DCA (Table 5).
* A value of 0 indicates that vinclozolin total residues of concern are stable to degradation.
Application methods, maximum rates per application and maximum number of applications per
year are based on current label directions for use of vinclozolin on turf grass. Values relevant to
these input parameters are provided in Table 9. The application date is not explicitly stated on
the label. The application date used in this modeling approach was October 2, which was based
on the date where the highest peak EEC was determined from the vinclozolin modeling that
involved investigation of application date on EECs (see Appendix D).
47
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Table 9. PRZM/EXAMS input parameters relevant to the use of vinclozolin.
Input Parameter
# applications/year
Maximum rate/application
(kg a.i./ha)
CAM
IPSCND
Application date
Application interval (days)
Spray drift fraction
Application efficiency
Value
3
1.51
2
1
October 2
10
0.01
0.99
Comments
Based on label
Equivalent to 1.35 Ibs a.i./A
For foliar application
In cases where CAM 2 is modeled, it is necessary to identify an
IPSCND value, which represents the deposition of vinclozolin in
post-season. An IPSCND value of 1 represents conversion of
vinclozolin remaining on foliage to surface application to the top
layer.
the
soil
Based on application date resulting in highest peak EEC observed for
vinclozolin modeling.
Shortest interval indicated on label.
Assumption relevant to ground application
3.2.3 Modeling Results
The peak one-in-ten year aquatic EEC for vinclozolin residues of concern is 52.0 |ig/L. One-in-
ten year 21-d and 60-d EECs were 51.1 and 49.9 |ig/L, respectively.
3.2.4 Surface Water Monitoring Data
No California-specific water monitoring data are available for vinclozolin or metabolites B, E , F
or S; however, data are available for its degradate of concern, 3,5-DCA, from the United States
Geological Survey's (USGS) National Water Quality Assessment (NAWQA). These data are
summarized below. No data are available in the CDPR Surface Water Database for vinclozolin
or 3,5-DCA.
3,5-DCA was detected in 1.3% of 308 surface water samples collected from 2001-2009 in CA.
The maximum reported concentration of 3,5-DCA was 0.0268 |ig/L. The level of quantification
of 3,5-DCA ranged 0.004-0.012 |ig/L(USGS 2009).
It should be noted that available monitoring data are not necessarily targeted to detect maximum
environmental concentrations of 3,5-DCA, and therefore may not be representative of peak
chemical concentrations present in the field.
48
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3.3 Ground Water Exposure Assessment
3.3.1 Modeling Approach
In order to estimate ground water EECs for vinclozolin residues of concern, Scigrow v2.3 was
run with the input parameters provided in Table 10.
Table 10. Input parameters for Scigrow v.2.3 used to represent vinclozolin residues of
concern.
Input Parameter
Maximum rate/application (Ibs a.i./A)
# applications/year
Koc (mL/g)
Soil metabolism half-life (days)
Value
1.35
3
532
10,000
Comments
Based on label
Based on label
Mean of Koc values for vinclozolin, metabolite E and 3,5-
DCA (Table 5)
Selected large value to represent stable.
3.3.2 Modeling Results
The resulting ground water EEC was 6.71 |ig/L. This value is an order of magnitude lower than
the surface water EECs generated using PRZM/EXAMS, indicating that the surface water EECs
represent more conservative values.
3.3.3 Ground Water Monitoring Data
No California-specific ground water monitoring data are available for vinclozolin or metabolites
B, E , F or S; however, data are available for 3,5-DCA, from NAWQA. During 2001-2008, 3,5-
DCA was detected in 5.7% of 229 ground water samples collected in CA. The maximum
detected concentration of 3,5-DCA was 0.0983 |ig/L (USGS 2009).
3.4 Terrestrial Exposure Assessment
T-REX (Version 1.4.1) is used to calculate dietary and dose-based EECs of vinclozolin for the
CRLF and its potential prey inhabiting terrestrial areas (i.e., small mammals, terrestrial-phase
amphibians and terrestrial insects). 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 vinclozolin to turf grass are considered,
as discussed in below.
Terrestrial EECs for foliar formulations of vinclozolin were derived for use on turf grass. Given
that no data on interception and subsequent dissipation from foliar surfaces is available for
vinclozolin, a default foliar dissipation half-life of 35 days is used based on the work of Willis
and McDowell (1987). Vinclozolin use on turf grass was modeled as 3 applications of 1.35 Ibs
a.i./A with an application interval of 10 days. An output from T-REX is available in Appendix
E.
49
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For modeling purposes, exposures of the CRLF to vinclozolin 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 11).
Dietary-based EECs for small and large insects reported by T-REX as well as the resulting
adjusted EECs are available in Table 11.
Table 11. Upper-bound Kenega Nomogram EECs for Dietary- and Dose-based Exposures
of the CRLF and its Prey to Vinclozolin
EEC Description
Dietary Based EEC for CRLF and terrestrial-phase amphibians (prey)
Dose Based for CRLF and terrestrial-phase amphibians (prey)
Dietary based EEC for small mammals (prey)
Dose based EEC for small mammals (prey)
Contact EEC for small insect (prey)
Contact EEC for large insect (prey)
Value
454
518
808
770
454
50
Unit
ppm
mg/kg-bw
ppm
mg/kg-bw
ppm
ppm
Exposure estimates are not derived for terrestrial plants since no toxicity data are available for
terrestrial plants with which to estimate potential risks from exposure.
3.5 Atmospheric Transport Assessment
Exposure of the CRLF to vinclozolin residues of concern through atmospheric transport and
deposition cannot be precluded. At this time, an approved model for estimating atmospheric
transport of pesticides and resulting exposure to organisms in areas receiving pesticide
deposition from atmospheric transport is not available. Potential mechanisms of transport of
vinclozolin residues of concern to the atmosphere via volatilization can only be discussed
qualitatively; however, transport via spray drift is quantified in this assessment.
3.5.1 Spray Drift
In cases where RQs exceed the LOG for terrestrial animals, AgDRIFT was used to characterize
the distance from the edge of the treated field where the risk extends. This was accomplished
using the Tier 1 ground setting, assuming a high boom and ASAE very fine to fine droplet size
distribution (90th percentile of data). These parameter values were selected to represent the most
conservative assumptions allowed by the Tier 1 ground setting of AgDRIFT. A terrestrial
assessment was conducted to determine the distance from the edge of the field where the point
deposition was below the Ibs a.i./A rate that was required to result in no LOG exceedances for a
taxa of concern (i.e., terrestrial-phase CRLF and mammals). The results of this spray drift
assessment are described in context of their relative RQ values in the risk description of this
assessment.
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3.5.2 Volatilization
As noted in section 2.4.1, in a laboratory volatility study, a maximum of 7.1% of applied
vinclozolin residues volatilized from sand over a 30-day period (MRID 42513101). In addition,
the vapor pressure of 3,5-DCA (2.12 x 10"2 torr, Table 4), indicates that vinclozolin residues of
concern may volatilize from treatment sites and be transported to non-target areas.
3.5.3 Air Monitoring Data
Atmospheric monitoring conducted in Lompoc, California, in the summer of 2000 indicated
quantifiable levels of vinclozolin at 16.2 ng/m3 (Segawa 2003). The highest daily amount of
vinclozolin used in Lompoc during 2000 was 119 Ibs and the highest daily amount used during
the monitoring period was 34.8 Ibs. According to California pesticide use reporting data, use of
vinclozolin in Santa Barbara County (where Lompoc is located) totaled 4,250 Ibs in the year
2000.
4.0 Effects Assessment
This assessment evaluates the potential for vinclozolin to directly or indirectly affect the CRLF
or modify its designated critical habitat. As previously discussed in Section 2.7, assessment
endpoints for the CRLF effects determination include direct toxic effects on the survival,
reproduction, and growth of CRLF, as well as indirect effects, such as reduction of the prey base
or modification of its habitat. In addition, potential modification of critical habitat is assessed by
evaluating effects to the PCEs, which are components of the critical habitat areas that provide
essential life cycle needs of the CRLF. Direct effects to the aquatic-phase of the CRLF are based
on toxicity information for freshwater fish, while terrestrial-phase effects are based on avian
toxicity data, 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 vinclozolin.
Limited toxicity data are available to characterize the effects of vinclozolin degradates that have
structures similar to the parent (metabolites B, E, S and F) to non-target organisms. As a
conservative estimate, it is assumed that data available for vinclozolin are representative of
effects to non-target organisms that may be caused by these metabolites. Based on the limited
data available for 3,5-DCA, the degradate appears to be less toxic than the parent compound, and
it is assumed that this chemical has a different mode of action compared to vinclozolin.
As described in the Agency's Overview Document (U.S. EPA, 2004), the most sensitive
endpoint for each taxon is used for risk estimation. For this assessment, evaluated taxa include
aquatic-phase amphibians, freshwater fish, freshwater invertebrates, aquatic plants, birds
(surrogate for terrestrial-phase amphibians), mammals, terrestrial invertebrates, and terrestrial
plants.
51
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Toxicity endpoints are established based on data generated from guideline studies submitted by
the registrant, and from open literature studies that meet the criteria for inclusion into the
ECOTOX database maintained by EPA/Office of Research and Development (ORD) (U.S. EPA,
2004). Open literature data presented in this assessment were obtained from ECOTOX
information obtained on February 29, 2009. In order to be included in the ECOTOX database,
papers must meet the following minimum criteria:
(1) the toxic effects are related to single chemical exposure;
(2) the toxic effects are on an aquatic or terrestrial plant or animal species;
(3) there is a biological effect on live, whole organisms;
(4) a concurrent environmental chemical concentration/dose or application rate is
reported; and
(5) there is an explicit duration of exposure.
Data that pass the ECOTOX screen are evaluated along with the registrant-submitted data, and
may be incorporated qualitatively or quantitatively into this endangered species assessment. In
general, effects data in the open literature that are more conservative than the registrant-
submitted data are considered. The degree to which open literature data are quantitatively or
qualitatively characterized for the effects determination is dependent on whether the information
is relevant to the assessment endpoints (i.e., maintenance of CRLF survival, reproduction, and
growth) identified in Section 2.8. For example, endpoints such as behavior modifications are
likely to be qualitatively evaluated, because quantitative relationships between modifications and
reduction in species survival, reproduction, and/or growth are not available. Although the effects
determination relies on endpoints that are relevant to the assessment endpoints of survival,
growth, or reproduction, it is important to note that the full suite of sublethal endpoints
potentially available in the effects literature (regardless of their significance to the assessment
endpoints) are considered to define the action area for vinclozolin.
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) are included in Appendix F. Appendix F 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.
A detailed spreadsheet of the available ECOTOX open literature data, including the full suite of
lethal and sublethal endpoints is presented in Appendix G. Appendix G also includes a
summary of the human health effects data for vinclozolin.
An open literature review was performed to ensure that all pertinent data were considered in this
assessment. In the survey of ECOTOX studies conducted in February 2009, sixty-four studies
were identified and citations are included in Appendix F. The studies were divided by their
taxon of focus which resulted in the following distribution: 21 avian studies, 2 mammal studies,
20 freshwater fish studies, 5 freshwater invertebrate studies, 7 aquatic plant studies, 3 terrestrial
plant study, 3 marine organism studies and 3 honey bee studies. Measurement endpoints from the
studies in each of these groups were then compared to the lowest toxicity value identified in
registrant-submitted studies presented earlier in this assessment to identify those studies which
52
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contained more sensitive endpoints. Nineteen studies were found to have endpoints at or below
the most sensitive registrant-submitted study endpoints. These 19 papers included 7 fish studies,
4 avian studies, 3 terrestrial plant studies, 2 aquatic invertebrate studies, 2 studies using both
mammals and birds, and 1 aquatic plant study. Each of these studies then went through a
primary assessment to determine their validity and relevance to the CRLF risk assessment.
Studies deemed suitable underwent secondary review in which their statistical and research
methods were scrutinized and evaluated.
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 vinclozolin. A summary of the available aquatic and terrestrial
ecotoxicity information and the incident information for vinclozolin are provided in Sections 4.1
through 4.4.
In addition to vinclozolin, its degradates, principally Metabolites B and E and 3,5-DCA are
known to be biologically active. The parent and its metabolites B and E can bind to the
androgen receptor (USEPA 2000a) while 3,5-DCA is classified as a potential carcinogen. A
detailed summary of the available ecotoxicity information for all vinclozolin degradates and
formulated products is presented in Appendix H.
Vinclozolin is not formulated with any other actives and there are no additional toxicity data on
vinclozolin [as a mixture] in either registrant-submitted and/or open literature sources.
4.1 Evaluation of Aquatic Ecotoxicity Studies for Vinclozolin
Table 12 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 is provided in Appendix
H.
Table 12. Freshwater Aquatic Toxicity Profile for Vinclozolin.
Assessment Endpoint
Acute Direct Toxicity to
Aquatic -Phase CRLF
Chronic Direct Toxicity
to Aquatic-Phase CRLF
Species
Rainbow Trout
(Oncorhynchus
mykiss)
Fathead Minnow
(Pimephales
promelas)
Toxicity
Value Used in
Risk
Assessment
LC50 = 2.84
mg/L
NOAEC 0.06
mg/L
Effect
Mortality
Reduced number
of
spawns/female
and reduced
hatching success
Citation
MRID
(Author &
Date)
264302
(Gelbke
1980)
Martinovic
et al. 2008
Study
Classification
Supplemental
Supplemental
(open
literature)
53
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Indirect Toxicity to
Aquatic -Phase CRLF via
Acute Toxicity to
Freshwater Invertebrates
(i.e., prey items)
Indirect Toxicity to
Aquatic -Phase CRLF via
Chronic Toxicity to
Freshwater Invertebrates
(i.e., prey items)
Indirect Toxicity to
Aquatic -Phase CRLF via
Toxicity to Non-vascular
Aquatic Plants
Indirect Toxicity to
Aquatic -Phase CRLF via
Toxicity to Vascular
Aquatic Plants
Daphnia magna
Daphnia magna
Navicula
pelliculosa
Lemna gibba
EC50 = 4.0
mg/L
NOAEC =0.79
mg/L
EC50<1.06
mg/L
EC50 >0.90
mg/L
Immobilization
Impaired
reproduction and
growth
Stimulated
growth by 94%
stimulated
growth by 7. 9%
Union
Carbide
1978
452473-01
(Drottar et
al.
1998)
423947-03
(Alexander
and Hughes
1992)
423947-05
(Alexander
and Hughes
1992)
Acceptable
Supplemental
Acceptable
Acceptable
Toxicity to aquatic fish and invertebrates is categorized using the system shown in Table 13
(U.S. EPA, 2004). Toxicity categories for aquatic plants have not been defined.
Table 13. Categories of Acute Toxicity for Fish and Aquatic Invertebrates.
LCSO (ppm)
<0.1
>0.1- 1
>1-10
> 10 - 100
>100
Toxicity Category
Very highly toxic
Highly toxic
Moderately toxic
Slightly toxic
Practically nontoxic
4.1.1 Toxicity to Freshwater Fish
Given that no vinclozolin 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 vinclozolin to
the CRLF. Effects to freshwater fish resulting from exposure to vinclozolin may indirectly affect
the CRLF via reduction in available food. As discussed in Section 2.5.3, over 50% of the prey
mass of the CRLF may consist of vertebrates such as mice, frogs, and fish (Hayes and Tennant,
1985). A summary of acute and chronic freshwater fish data, including data from the open
literature, is provided below.
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4.1.1.1 Freshwater Fish: Acute Exposure (Mortality) Studies
The most sensitive freshwater fish species tested is the rainbow trout (Oncorhynchus mykiss) and
resulted in a 96-hr LCso of 2.84 mg a.i./L. Even with elevated co-solvent concentrations,
precipitation of the test material was still a problem in the study. The study did not report
whether water samples were centrifuged and/or filtered prior to analysis, so actual exposure
concentrations may be uncertain. Based on the results of this study, vinclozolin is classified as
moderately toxic to fish on an acute exposure basis. The mortality data from this study were
analyzed using the moving average method to derive an LCso value since the pattern of mortality
across exposure concentrations did not support the use of probit analysis. As such, a probit dose-
response slope is not available and OPP's default probit dose-response slope of 4.5 is use to
estimate the likelihood of individual mortality.
No acceptable studies were identified in the open literature that are more sensitive that the
available registrant-submitted data.
4.1.1.2 Freshwater Fish: Chronic Exposure Studies
In a study by Makynen et al. 2000 (MRID 452437-04), fathead minnows (Pimephales promelas)
were exposed for 34 days beginning 6 hours post-hatch and then monitored the fish for 4 to 6
months post-exposure. This early life stage study resulted in a NOAEC and LOAEC of 600 and
1200 |ig/L, respectively, based on 34-day (end of exposure period) body weights; this effect
though appeared to be transitory as 90-day fish weights were not statistically different between
vinclozolin-treated and control fish. The study also examined the effect of vinclozolin on adult
fish in a 21-day exposure. Based on reductions (63% decrease) in the ratio of ovary weight to
body weight, i.e. the gonadosomatic index (GSI), the NOAEC and the LOAEC are 200 and 700
|ig/L; the reduction in GSI was attributed to a retarded maturation of oocytes. The GSI is
considered an index of reproductive fitness and reductions in the GSI may reflect a reduction of
the reproductive success of the test animal. Additionally, plasma p-estradiol concentrations were
roughly 1.8X higher in males treated with 700 |ig/L; however, histology did not indicate any
qualitative differences between treated and control testes as all were well developed with mature
spermatozoa.
In a fish early-life stage study (MRID 452437-04), embryonic (<6 hr old) fathead minnows were
exposed to vinclozolin at mean measured concentrations ranging from 0.09 - 1.2 mg/L for 34
days and then monitored 4-6 months. Based on the results of this study, there was a significant
reduction (33%) in growth (34-day body weight) at 1.2 mg/L; therefore, the NOAEC from this
study is 0.54 mg/L.
A fish modified life-cycle study of the fathead minnow with vinclozolin in the presence of
metabolites B and E was conducted where 8-month old fish were exposed for 112 days under
flow-through conditions (MRID 452437-03). The mean measured concentration of total
vinclozolin residues (parent plus metabolites B and E) was 0.12 mg/L. The number of
spawns/female in the F0 generation was statistically reduced by 54% compared to controls;
however, the number of eggs per spawn was significantly higher (73% increase) in the
vinclozolin-treated fish relative to controls. In the FI generation, hatch survival was statistically
55
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reduced by roughly 35% in the vinclozolin-treated animals relative to controls. Since this study
utilized only a single treatment group and control, it is not possible to establish a NOAEC; as
such, the NOAECX0.12 mg/L.
Of the three chronic toxicity studies of vinclozolin, the 112-day study with adult fish provides
the most sensitive endpoint, i.e., NOAECX0.12 mg/L.
Open literature also contained supplemental information on the chronic effects of vinclozolin on
fish. Bayley et al. 2003 reported that 10 to 14-wk exposures of male guppies (Poecilia
reticulate) to vinclozolin in their diet at 1 and 10 |ig/mg diet significantly (p<0.05) reduced
sperm count and clutch size; however, there were significant uncertainties in actual exposure
levels used in this study. In a study of Japanese medaka (Oryzias latipe), Kiparissis et al. 2003
exposed fish for 100 days starting at hatch; the study reported significant (p<0.01) effects on
spermatogenesis at concentrations as low as 2.5 mg/L. In the Kiparissis study, there were no
significant effects on sex ratio or the incidence of intersex; the results from this study provide
qualitative evidence that chronic exposure to vinclozolin can result in reproductive effects in
fish; however, the data cannot be used quantitatively since there was uncertainty regarding the
study's exposure conditions.
In a study by Bayley et al. 2002, guppies were exposed to vinclozolin in their feed for 24 days.
The intent of the study was to expose the fish during sexual development in their juvenile stage
and then to track sexual development in males. According to the study exposure to vinclozolin
at 0.1 and 10 |ig/mg diet significantly altered sex ratios of offspring born to the treated fish
resulting in more females; at the highest treatment concentration, offspring were 71% female
while controls were 48% females. The study also reported significant (p<0.01) reductions in
adult size (mm2) and in sperm count at both treatment levels; however, the percent reductions
could not be determined from the study. Gonadopodium length in males treated with 0.1 |ig/mg
diet was also reduced relative to controls. Because of uncertainties regarding the study's
exposure conditions, these data cannot be used quantitatively; however, they do provide
qualitative evidence that chronic exposure to vinclozolin effects both reproduction and growth.
In a 21-day reproductive study of fathead minnows (Matinovic et al. 2008), there was a
concentration dependent decline in the cumulative number of eggs produced and female fish
exposed to 450 |ig/L failed to reproduce. Females exposed to vinclozolin had significantly
higher (p<0.05) body weights at each of the vinclozolin concentrations tested; body weights were
roughly 22% higher. The GSI of males exposed to vinclozolin at 255 and 450 |ig/L was
significantly different (p<0.05), by roughly a factor of 1.7X, compared to controls. Treatment
with vinclozolin at 450 |ig/L was also associated with significant reduction in secondary sexual
characteristics such as skin tubercle development and dorsal pad development used in attracting
mates. Also, at both 255 and 450 |ig/L, plasma vitellogenin levels were significantly elevated in
females. At 450 |ig/L, the severity of oocyte atresia was significantly increased (90%) compared
to controls (20%). The relevancy of the increased female body weight in this study at 60 |ig/L is
unclear however, the reproductive effects observed at 255 and 450 |ig/L are consistent with
effects discussed above. As such, the NOAEC for these effects would be 60 jig/L and the
LOAEC would be 255 |ig/L. The NOAEC of 60 jig/L is more sensitive than the value obtained
56
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from registrant-submitted data and will serve as the chronic toxicity endpoint for this risk
assessment.
4.1.2 Toxicity to Freshwater Invertebrates
Freshwater aquatic invertebrate toxicity data were used to assess potential indirect effects of
vinclozolin to the CRLF. Effects to freshwater invertebrates resulting from exposure to
vinclozolin may indirectly affect the CRLF via reduction in available food items. As discussed
in Section 2.5.3, the main food source for juvenile aquatic- and terrestrial-phase CRLFs is
thought to be aquatic invertebrates found along the shoreline and on the water surface, including
aquatic sowbugs, larval alderflies and water striders. A summary of acute and chronic freshwater
invertebrate data, including data published in the open literature, is provided below.
4.1.2.1 Freshwater Invertebrates: Acute Exposure (Mortality) Studies
Based on a 48-hr acute toxicity test with waterfleas (Daphnia magna), vinclozolin is classified as
moderately toxic (ECso=4.0 mg/L) on an acute exposure basis.
Open literature was reviewed to determine whether there were more sensitive measures of acute
toxicity for aquatic invertebrates. In a study by Zavala-Aquirre et al. 2007 using the rotifer
Brachionus calyciflorus, the 24-hr LCso was 30.5 mg/L. Additionally, in a study by Haeba et al.
2008, the 48-hr acute toxicity of vinclozolin was evaluated using D. magna; the study reported
an LCso>3 mg/L with no mortality in any of the treatment groups. Both of these toxicity values
however, are less sensitive that what is available through registrant-submitted data.
4.1.2.2 Freshwater Invertebrates: Chronic Exposure (Reproduction) Studies
In a 21-day flow-through full life-cycle study with D. magna (MRID 452473-01), growth (length
and weight) was significantly reduced at 1.4 mg/L (LOAEC) and the NOAEC was determined to
be 0.79 mg/L. At the LOAEC, mean body length was reduced by 3.8% and mean total dry
weight was reduced by 11%. Reproduction was also affected with the mean number of young
per adult reduced by 17% at the LOAEC.
Open literature was reviewed to determine whether there were more sensitive measures of
chronic toxicity for aquatic invertebrates. In a study by Haeba et al. 2008, D. magna were
exposed for 4-6 days under static renewal conditions. Vinclozolin significantly (p<0.05)
altered sex ratio, reducing the number of males by a factor of 2; based on the results of this
study, the NOAEC for sex ratio would be 0.1 mg/L or 100 |ig/L. However, the study did not
measure exposure concentrations and it relied on dimethylsulfoxide (DMSO) as a co-solvent that
may have affected the uptake of vinclozolin. The study is considered supplemental and as
providing useful qualitative information on the effects of vinclozolin exposure on freshwater
aquatic invertebrates.
In a study of the ramshead snail (Marisa cornuarietis) Tillmann et al. 2001 reports that juvenile
snails exposed to vinclozolin for 5 months showed a significant albeit transient effect on penis
length and penis sheath at 0.03 and 1.0 |ig/L during the first couple months of the study. By the
57
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fourth month of the study, there was no difference between vinclozolin-treated and control
animals. The study is confounded though by the fact that neither the treated nor control animals
spawned and it is difficult to determine the relevancy of the decreased penis length and sheath to
the reproductive success of the test animals.
4.1.3 Toxicity to Aquatic Plants
Aquatic plant toxicity studies were used as one of the measures of effect to evaluate whether
vinclozolin may affect primary production and the availability of aquatic plants as food for
CRLF tadpoles. Primary productivity is essential for indirectly supporting the growth and
abundance of the CRLF.
Only Tier I studies of aquatic plants are available for vinclozolin. Only one nonvascular plant
species (Navicula pelliculosd) exhibited an effect of greater than 50%. The remainder of the
species tested exhibited less than a 10% at the highest concentration tested, i.e., 1 mg/L.
The only nonvascular plant species tested to exhibit an effect greater than 50% was N.
pelliculosa. In a 5-day study with a mean measured concentration of 1.06 mg a.i./L, the
compound stimulated growth by 94.5% (MRTD 423947-03). Growth stimulation like growth
inhibition is considered an effect which can alter the number of plants in an aquatic community.
Growth stimulation without sufficient nutrients to support such activity can result in aquatic
plant blooms that cannot be sustained and may ultimately result in decreased water quality as the
bloom rapidly subsides. Since this was a limit test, it is not possible to determine the ECso from
the available information. All that can be said is that the EC50 is likely less than 1.06 mg a.i/L;
however, it is uncertain how much less. For the purposes of this assessment though, the ECso is
assumed to be <1.06 mg a.i./L. None of the other aquatic plants tested in registrant-submitted
studies (Pseudokirchneriella subcapitata, Anabaena flos-aquae, and Skeletonema costatuni)
exhibited greater than a 8% effect at the maximum concentration tested (limit test concentrations
ranging between 0.87 - 1.02 mg a.i./L).
For vascular aquatic plants, only a limit test is available for duckweed (Lemna gibba), and
vinclozolin exposure resulted in a stimulation of growth (MRLD 423947-05). At the maximum
concentration tested (0.90 mg a.i./L) and following a 14-day exposure, plant growth was
stimulated by 7.9%. For the purposes of this assessment the ECso is assumed to be >0.90 mg
a.i./L.
4.2 Toxicity of Vinclozolin to Terrestrial Organisms
Table 14 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. Acute toxicity to terrestrial animals is categorized using the classification
system shown in Table 15 (U.S. EPA, 2004). Toxicity categories for terrestrial plants have not
been defined.
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Table 14. Terrestrial Toxicity Profile for Vinciozolin.
Assessment Endpoint
Acute Dose-based
Direct Toxicity to
Terrestrial-Phase
CRLF
Acute Dietary-based
Direct Toxicity to
Terrestrial-Phase
CRLF
Chronic Direct
Toxicity to Terrestrial-
Phase CRLF
Indirect Toxicity to
Terrestrial-Phase
CRLF (via acute
toxicity to mammalian
prey items)
Indirect Toxicity to
Terrestrial-Phase
CRLF (via chronic
toxicity to mammalian
prey items)
Indirect Toxicity to
Terrestrial-Phase
CRLF (via acute
toxicity to terrestrial
invertebrate prey
items)
Species
Northern
Bob white
Quail
(Colinus
virginianus)
Northern
Bobwhite
Quail
Northern
Bobwhite
Quail
Laboratory Rat
(Rattus
norvegicus)
Laboratory Rat
Honey bee
(Apis
mellifera)
Toxicity
Value Used in
Risk
Assessment
LD50>2,510
mg/kg
LC50 >5,620
mg/kg diet
NOAEC = 50
mg/kg diet
LD50 >10,000
mg/kg bw
NOAEL=30
mg/kg/day
LD50 >100
ug/bee
Effect
Mortality
Mortality
Reduced numbers
of eggs laid;
eggshell thinning;
reduced 14-day
survival of
hatchlings
Mortality
Reproductive tract
malformations and
reproductive
failure.
Mortality
Citation
MRID
(Author &
Date)
92194-002
(Fink, 1978)
92194-003
(Fink, 1978)
428689-01
(Munk,
1993)
921940-10
O'Reilly
425813-01
Hellwig
1993
409928-01
(Hoxter
1988)
Study
Classification
Acceptable
Acceptable
Supplemental
Acceptable
Acceptable
Acceptable
* although these endpoints are not typically used in ecological risk assessment, this study is used as a surrogate estimate of the NOAEC since the
rat 2-generation reproduction study showing frank effects on rat reproductive organ relied on an estimated NOAEC (point of departure) of 3
mg/kg/day.
Table 15. Categories of Acute Toxicity for Avian and Mammalian Studies.
Toxicity Category
Very highly toxic
Highly toxic
Moderately toxic
Slightly toxic
Practically non-toxic
Oral LDSO
< 10 mg/kg
10-50 mg/kg
51 -500 mg/kg
50 1-2000 mg/kg
> 2000 mg/kg
Dietary LCSO
< 50 ppm
50 - 500 ppm
501- 1000 ppm
1001 - 5000 ppm
> 5000 ppm
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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 vinclozolin; therefore, acute and chronic avian
toxicity data are used to assess the potential direct effects of vinclozolin to terrestrial-phase
CRLFs.
4.2.1.1 Birds: Acute Exposure (Mortality) Studies
Vinclozolin is classified as practically nontoxic to birds on both an acute oral and subacute
dietary exposure basis. The acute oral LD50 and subacute dietary LCso for bobwhite quail
(Colinus virginianus) are 2,510 mg/kg bw and 5,620 mg/kg diet, respectively. In the acute oral
toxicity study (MRID 92194-002), no mortality occurred in any of the treatment levels. In the
subacute dietary toxicity study with bobwhite quail, while there was sporadic mortality across
treatment groups, no dose-related mortality was reported. Sublethal effects were not reported in
the acute oral and subacute dietary toxicity studies with quail.
Open literature was reviewed to determine whether any more sensitive acute toxicity endpoints
are available for birds. In a study by Ronis et al. 1998, male bobwhite quail (200 g) were given
three consecutive doses (gavage) of vinclozolin at 400 mg/kg bw/day, and the birds were
sacrificed 48 hours after the last dose. Under the conditions tested, males exhibited statistically
significant (p<0.05) induction in two markers for testosterone metabolism, i.e., testosterone 2P-
hydroxylase (38% increase) and testosterone 15p-hydroxylase (67% increase), relative to
controls. The authors also reported significantly induced cytochrome P450 enzymes. The
dosing regime used in this study, i.e., three consecutive days of dosing, was selected because it
was known to induce cytochrome P450 activity; however, its relevance to what may occur in the
field is uncertain. While the information contained in this study indicates and effect that could
potential impact steroidogenesis, the study is of limited utility as a measurement endpoint for
acute and/or subacute toxicity.
In another study by Ronis et al. 1995, male bobwhite quail (200 g) were again dosed by gavage
at a rate of 400 mg/kg bw per day for three consecutive days and were sacrificed 48 hours after
treatment. Under the conditions tested liver cytochrome P450 enzyme activity was significantly
(p<0.005) increased by an order of magnitude. Liver to body weight ratio, i.e., the
hepatosomatic index (HSI), was also significantly (p<0.05) increased (30%) relative to controls
and likely reflected the increase in enzymatic activity. Similar to the previous study, the exposure
regime used in this study is relatively unusual and it is uncertain how similar exposure may occur
under field conditions. Additionally, the endpoints identified in this study, i.e., enzyme
induction and increased HIS, are not typically used in evaluating acute toxicity.
In a third study by Ronis et al. 1994, male bobwhite quail (200 g) were again dosed via gavage
using three consecutive treatments with 400 mg/kg bw/day and the birds were sacrificed 48
hours after the third treatment. Under the conditions tested, vinclozolin significantly and
simultaneously affected different subfamilies of hepatic P450 enzyme activity in the birds. The
60
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authors speculated that the increased cytochrome P450 activity could enhance the activation of
other chemicals, e.g., the activation of organophosphate pesticides to their oxon, which may co-
occur in the environment and in doing so result in the enhanced toxicity of the chemical mixture.
In a study by Riviere et al. 1983, Japanese quail (Coturnix coturnix) received diets of 2000 ppm
for seven days at which time the birds were sacrificed. Vinclozolin-treated birds showed a
significant (p<0.05) difference in liver weights, HIS, cytochrome P450 activity (p<0.01),
NADPH-cytochrome c reductase (p<0.01), aniline hyroxylase (p<0.05), aldrin epoxidase
(p<0.01) and 7-ethoxyresorufin dealkylase activity (p<0.01). Again though, the induction of
hepatic enzyme activity is not typically used as a measure of acute toxicity.
4.2.1.2 Birds: Chronic Exposure (Growth, Reproduction) Studies
In an avian reproduction study of bobwhite quail, exposure to vinclozolin resulted in NOAEC of
50 mg/kg diet and a LOAEC of 125 mg/kg diet (MRID 428689-01). The LOAEC was based on
significantly reduced number of eggs laid (13% reduction), decreased eggshell thickness (4.8%
reduction), and reduced proportion of 14-day old survivors of chicks hatched (15% reduction).
Also at the LOAEC, early embryonic mortalities increased by 37% relative to controls and total
embryonic deaths were 33% higher than controls.
Open literature was reviewed to determine whether any more sensitive chronic toxicity endpoints
are available for vinclozolin in birds. In a study by Niemann et al. 2004, Japanese quail
received dietary exposures for 6 weeks at either 125 or 500 mg/kg diet. After 6 weeks of
treatment, the number of spermatids per testes was statistically different (p<0.05) in birds treated
with 500 ppm diet; on average, spermatids were 26% lower in the testes of birds treated with 500
ppm diet. The authors also report that sex ratio of chicks was significantly different (p<0.05)
among offspring of quail feed at 500 ppm; treated animals had a ratio of 39:43 (male:female)
while controls had a ratio of 45:24. Although the authors report that eggshell thickness (mm) of
cracked eggs was significantly different (p<0.05) from vinclozolin-treated quail compared to
controls; however, these differences existed prior to study initiation and likely reflect an artifact
of the study. The authors reported that fertility and reproductive performance were not affected
up to the highest dietary concentration tested, i.e., 500 ppm; however, spermatid counts and
histology provided evidence of an inhibition of spermatogenesis at both dietary concentrations.
Based on shifts in sex ratio and reductions in spermatids, the NOAEC for this study is 125 ppm
and the LOAEC is 500 ppm; however, these endpoints are not more sensitive than the registrant-
submitted data.
4.2.1.3 Terrestrial-phase Amphibian Acute and Chronic Studies
No acute or chronic toxicity data on amphibians are available through registrant-submitted or
open literature studies.
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Toxicity to Mammals
Mammalian toxicity data are used to assess potential indirect effects of vinclozolin to the
terrestrial-phase CRLF. Effects to small mammals resulting from exposure to vinclozolin may
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).
4.2.1.4 Mammals: Acute Exposure (Mortality) Studies
With an LD50>10,000 mg/kg bw (USEPA 2000a), vinclozolin is classified as practically
nontoxic to rats on an acute oral exposure basis.
Two acute toxicity studies involving mammals were identified in the open literature and were by
the same authors, i.e., Ronis and Badger 1995 and Ronis et al. 1994 discussed for the acute
toxicity of vinclozolin on birds. Each of these studies relied on three consecutive doses (by
gavage) of vinclozolin at 400 mg/kg bw in 300 g Sprague-Dawley rats (Rattus norvegicus). In
the Ronis et al. 1994 study, vinclozolin significantly (P<0.005) raised cytochrome P450 (Cyt-
P450) levels by a factor of 3 - 4 fold in both rats and significantly (P<.0.05) elevated levels of
cytochrome b5 and Cyt-P450 reductase by factors of 2 - 4 fold. EROD and CYP 2B1/2-
dependent BROD were increased 12- and 300-fold by vinclozolin treatment, respectively.
Vinclozolin increased CYP lA2-dependent MROD and BYP2Bl/2-dependent PROD 30- to 40-
fold, respectively. Androstendione, 2P- and 6p-hydroxytestosterone formation was significantly
(P<0.05) increased in rats exposed to vinclozolin. In the Ronis and Badger 1995 study
cytochrome P450 activity was significantly induced (2.9X increase) in rats and in the Ronis et al.
1998 study. As stated previously, the relevancy of the exposure conditions used in these studies
to ecological risk assessment is uncertain; however, under the conditions tested, vinclozolin
treatment resulted in a significant induction of hepatic microsomal enzyme activity. Since this
measurement endpoint is not typically used to assess acute toxicity, it is not used in this
assessment.
4.2.1.5 Mammals: Chronic Exposure (Growth, Reproduction) Studies
According to the RED (USEPA 2000), the principal toxic effects of vinclozolin and/or its
metabolites in mammals are related to its anti-androgenic activity and its ability to act as a
competitive antagonist at the androgen receptor. At low dose levels (>3 mg/kg/day), the most
androgen sensitive effects are noted, such as decreased prostate weight, weight reductions in
other sex organs; at higher concentrations, sex organ malformations are observed. Vinclozolin
and its metabolites also cause Leydig cell (testicular) tumors in rats via its antiandrogenic
mechanism of action. The extent to which these effects relate to marked impacts on reproduction
are uncertain; however, this assessment is intentionally conservative to account for the
uncertainty given the inter-related nature of endocrine-mediated processes. However, in the rat
2-generation study, vinclozolin was associated with decreased epididymal weights with a
LOAEC of 30 mg/kg/day and an estimated NOAEC (point of departure) of 4.9 mg/kg/day
(USEPA . Since the point of departure is an estimated value for a frank endpoint, i.e., decreased
reproductive organ weight, this assessment relies on the measured NOAEC from the chronic
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dietary toxicity study. Vinclozolin is also classified as a possible human carcinogen based on
Leydig (interstitial testicular) cell tumors in chronic and carcinogenicity studies. However, frank
effects on apical endpoints were not observed at the NOAEL/NOAEC discussed above. Frank
effects on reproduction were noted in the rat 2-generation reproduction study (Hellwig 1992)
where adult male offspring exhibited genital and reproductive tract malformations and sire no
offspring at dietary treatments of 1000 (LOAEL; 96 mg/kg/day) and 3000 ppm. Based on this
study, the NOAEL is 300 ppm (30 mg/kg bw/day) and it is this value that will be used to assess
risk to mammals serving as forage for terrestrial-phase CRLF..
No additional chronic mammalian toxicity data were obtained from the open literature that are
more sensitive than the registrant-submitted data.
4.2.2 Toxicity to Terrestrial Invertebrates
Terrestrial invertebrate toxicity data are used to assess potential indirect effects of vinclozolin to
the terrestrial-phase CRLF. Effects to terrestrial invertebrates resulting from exposure to
vinclozolin may also indirectly affect the CRLF via reduction in available food.
An acute contact toxicity study with honeybees (Apis melliferd) resulted in an LD50 greater than
the highest dose tested (100 jig/bee) (MRID 409928-01). As such, vinclozolin is classified as
practically nontoxic to honeybees and an acute contact exposure basis, i.e., LD50>100 jig/bee.
No additional terrestrial invertebrate toxicity date were identified in the open literature.
4.2.3 Toxicity to Terrestrial Plants
Terrestrial plant toxicity data are used to evaluate the potential for vinclozolin 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.
No registrant-submitted data are available on the potential effects of vinclozolin on terrestrial
plants. Several terrestrial plant studies were identified in the open literature for vinclozolin. In a
study by Rouchard et al. 1984, the effects of formulated vinclozolin on carotenoid pigment in
lettuce (Lactuca saliva) was evaluated. Ronilan® (vinclozolin 50 % a.i. treated at 10 g
Ronilan®/acre) was applied to lettuce at the 12-leaf stage. Although vinclozolin did not have any
significant effect on carotenoid pigment, treated plants were significantly larger (47% increase in
fresh weight relative to control) 14 days after treatment; however, by 32 days after treatment
there was not significant difference. Because of uncertainties regarding exposure conditions in
the study, it cannot be used quantitatively; however, it provides qualitative information that
vinclozolin can affect terrestrial plants.
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In a study by Lorenzini et al. 1987, the ability of formulated vinclozolin to counteract the effects
of ozone damage to tobacco plants (Nicotiana tabacus) were examined. In this study (Rovral®,
50% a.i. applied at 1500 g a.i./ha) did not prevent or combat ozone damage. In this case, at the
application rate used, vinclozolin treatment did not appear to harm the plants; however, only a
limited number of measurements were conducted and as such, the study provides little insight on
the potential effects of vinclozolin on terrestrial plants.
In a study by Olien et al. 1995, the effect of vinclozolin alone and in combination with the
fertilizer ammonium thiosulphate in controlling brown rot (Monilinia fructicola) on peach trees
(Prunus persica) was examined. Vinclozolin was applied in Ronilan® DF (2.4 g/L) at a rate of
1.58 kg a.i./ha. The study showed that vinclozolin was effective in reducing M. fructicola
blossom blight cankers per tree. The study examines a relatively specific endpoint and it is
difficult to gauge the overall phytotoxicity potential of either vinclozolin from this study. The
study is essentially measures efficacy relative to plant damage from brown rot fungus. Frost
damaged 10-20% of the flowers; it's unclear how this may have impacted the study.
4.3 Toxicityof3,5-DCA
Several studies were identified in the open literature for 3,5-DCA. The only data available for
fish in the open literature was a 14-day LCso value of 3900 ug/L for guppies (Poecilia reticulate)
(Maas-Diepeveen and van Leeuwen 1986). These data suggest that guppies are considerably less
sensitive to the 3,5-DCA degradate than other species tested against the parent compound.
Rainbow trout exposed to vinclozolin had an LCso of 2840 ug/L after 4 days of treatment
compared to the LCso of 3900 ug/L for guppies after exposure to the degradate for roughly 3.5
times longer.
In a 48-hr study with waterfleas (D. magnd) the ECso was 1120 ug/L (Maas-Diepeveen and van
Leeuwen 1986) and is roughly 1.4 times less sensitive than the equivalent toxicity endpoint for
waterfleas using the parent compound (48-hr EC50=790 ug/L). A 96-hr study of 3,5-DCA with
shrimp (Crangon septemspinosa) resulted in an LCso value of 2500 ug/L (McLeese et al. 1979)
and is considerably less toxic than the parent compound. Finally, in a 96-hr study with green
algae (Chlorella pyrenoidosa), the ECso was 7500 ug/L (Maas-Diepeveen and van Leeuwen
1986) and is seven times less toxic than the estimate for the most sensitive freshwater
nonvascular plant (N. pelliculosd) where a 5-day study with a mean measured concentration of
1.06 mg a.i./L, the compound stimulated growth by 94.5% Therefore, based on the weight of
evidence provided through toxicity values reported in the open literature, 3,5-DCA is considered
at least 1.4 times less toxic to aquatic organisms than the parent compound. Based on measured
and estimated toxicity values for 3,5-DCA, the compound would be classified as moderately
toxic to aquatic animals on an acute exposure basis.
A single chronic toxicity value for 3,5-DCA is available through the open literature in which
zebrafish (Brachydario rerio) were exposed for 28 days and resulted in a NOAEC of 1000 ug/L
(1 mg/L) (van Leeuwen et al. 1990) based on survival, hatching and growth. Analytical
measurements for 3,5-DCA were highly uncertain in the study and the extent of the effect on
survival, hatching and growth is not discussed. No invertebrate chronic toxicity data were
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available from the open literature for 3,5-DCA. With an measured NOAEC of 1000 |ig/L, 3,5-
DCA is less toxic on a chronic exposure basis compared to the most sensitive chronic toxicity
estimate for the parent, i.e., fathead minnow NOAEC=60 |ig/L.
4.4 Incident Database Review
A review of the EIIS database for ecological incidents involving vinclozolin was completed on
August 10, 2009. No incidents were reported in the EIIS involving vinclozolin. Additionally,
the American Bird Conservancy's Avian Incident Monitoring System (AIMS) was also searched
on August 10, 2009, and again, no incidents associated with vinclozolin are reported.
4.5 Endocrine Disrupter Effects
Although the EPA has developed a process for determining whether a chemical acts on
endocrine-mediated processes, the Tier I tests of the Endocrine Disruption Screening Program
are only just being implemented. However, according to the RED (USEPA 2000), vinclozolin
and some of its metabolites are already known to interfere with the endocrine system, exerting
their effects most dramatically during the developmental stages of animals, resulting in
reproductive effects in lab animals. Although vinclozolin binds weakly to the androgen receptor,
metabolites B and E have higher binding affinity for the androgen receptor. According to the
RED chapter, all androgen dependent functions are reduced; the more sensitive organs and
functions are the male sex organ weight reductions, reduced fertility and abnormal or ambiguous
sexual differentiation in the male rat (USEPA 2000).
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5.0 Risk Characterization
Risk characterization is the integration of the exposure and effects characterizations. Risk
characterization is used to determine the potential for direct and/or indirect effects to the CRLF
or for modification to its designated critical habitat from the use of vinclozolin 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 B). For acute exposures to the CRLF and its animal prey in
aquatic habitats, as well as terrestrial invertebrates, the LOG is 0.05. For acute exposures to the
CRLF and mammals, the LOG is 0.1. The LOG for chronic exposures to CRLF and its prey, as
well as acute exposures to plants is 1.0.
Risk to the aquatic-phase CRLF is estimated by calculating the ratio of exposure to toxicity using
l-in-10 year EECs based on the label-recommended vinclozolin usage scenarios summarized in
the use characterization and the appropriate aquatic toxicity endpoint from Table 12. 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 vinclozolin and the
appropriate toxicity endpoint from Table 14. As discussed earlier, no toxicity data are available
for terrestrial plants and as a result risk cannot be estimated for these taxa.
5.1.1 Exposures in the Aquatic Habitat
5.1.1.1 Direct Effects to Aquatic-Phase CRLF
Direct effects to the aquatic-phase CRLF are based on peak EECs in the standard pond and the
lowest acute toxicity value for freshwater fish. In order to assess direct chronic risks to the
CRLF, 60-day EECs and the lowest chronic toxicity value for freshwater fish are used.
Although vinclozolin is moderately toxic to fish on an acute exposure basis (LCso=2840 ug/L),
the peak EEC (52.0 ug/L), representing vinclozolin residues of concern results in an acute RQ
(0.018) that is below the endangered species LOG of 0.05 (Table 16). As such, risk of acute
effects (mortality) to listed species from the use of vinclozolin on turf is presumed to be low.
However, vinclozolin exposure resulted in effects on growth and reproduction in fathead
minnows (NOAEC=0.06 mg/L) following 21-day exposure to residues of vinclozolin; the RQ
value (0.83) is below the chronic risk LOG of 1.0 (Table 16). Based on acute and chronic RQ
values below LOCs, vinclozolin's is not expected to affect the aquatic-phase of the CRLF.
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Table 16. Summary of Direct Effect RQs for the Aquatic-phase CRLF.
Direct Effects
to CRLFa
Acute Direct
Toxicity
Chronic Direct
Toxicity
Surrogate
Species
Rainbow
trout
Fathead
minnow
Toxicity
Value (jig/L)
LC50 = 2840
NOAEC= 60
ug/L
EEC (jig/L)b
Peak: 52.0
60-day: 49.9
RQ
0.018d
0.83e
Probability of
Individual Effect
at
ESLOC
Iin4.18xl08
(1 in 216 to 1 in
1.75 x 1031)c
Probability of
Individual
Effect at RQ
Iin4.86xl014
Not calculated for chronic endpoints
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 vinclozolin on turf at 1.3 5 Ib a. i/A representing vinclozolin residues of concern
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 LOG of 0.05.
e RQ less than chronic risk LOC of 1.0.
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 vinclozolin to the aquatic-phase CRLF (tadpoles) via reduction in non-
vascular aquatic plants in its diet are based on peak EECs from the standard pond and the lowest
toxicity value (ECso) for aquatic non-vascular plants. The most sensitive nonvascular aquatic
plant is N. pelliculosa with an ECso value of <1060 ug/L. Based on a peak EEC of 52.0 ug/L
representing vinclozolin residues of concern, the RQ is >0.05. Since the aquatic plant toxicity
data are based on a limit test, the concentration required to result in an effect of 50% is uncertain.
As noted previously, none on the other aquatic non-vascular plants tested had growth effects at
treatment concentrations ranging between 0.87 - 1.02 mg a.i./L. The maximum effect based on
either inhibition or stimulation of growth on these test species was less than 8%. Given that none
of the other aquatic plant species tested exhibited growth effects greater 8% at concentrations
roughly 28 times higher than the maximum total toxic residues estimated for vinclozolin and its
degradates, vinclozolin is not likely to indirectly affect the CRLF via reduction in non-vascular
plants.
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Aquatic Invertebrates
Indirect acute effects to the aquatic-phase CRLF via effects to prey (invertebrates) in aquatic
habitats are based on peak EECs in the standard pond and the lowest acute toxicity value for
freshwater invertebrates. For chronic risks, 21-day EECs and the lowest chronic toxicity value
for invertebrates are used to derive RQs. Although vinclozolin is moderately toxic (ECso=4.0
mg/L) on an acute exposure basis, the peak EEC based on total toxic residues is such that the
resultant acute RQ (0.013) is below the acute risk to listed species LOG of 0.05. Further, the
chronic toxicity endpoint (NOAEC=790 ug/L) is sufficiently greater than the 21-day EEC for
vinclozolin residues of concern (51.1 ug/L) to yield an RQ (0.065) that is below the chronic risk
LOG of 1; therefore, vinclozolin is not likely to indirectly affect the CRLF via reduction in
freshwater invertebrates prey items.
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 16) are used to assess potential
indirect effects to the CRLF based on a reduction in freshwater fish and frogs as food items.
Based on data indicating that vinclozolin is moderately toxic to fish and by extension to aquatic-
phase amphibians, on an acute exposure basis and RQ values well below the acute risk LOG, the
likelihood of acute effects on fish/amphibians serving as prey for adult aquatic-phase CRLF is
considered low. Similarly, the chronic RQ for fish is below the chronic risk LOG for
fish/amphibians and as such, the likelihood of chronic effects on fish/amphibians serving as prey
for aquatic-phase CRLF is considered low. Based on the available data, vinclozolin is not likely
to indirectly affect the CRLF via reduction in freshwater fish and frogs as food items.
5.1.1.3 Indirect Effects to CRLF via Reduction in Habitat and/or Primary
Productivity (Freshwater Aquatic Plants)
Indirect effects to the CRLF via direct toxicity to aquatic plants are estimated using the most
sensitive non-vascular and vascular plant toxicity endpoints. Because there are no obligate
relationships between the CRLF and any aquatic plant species, the most sensitive ECso values,
rather than NOAEC values, were used to derive RQs.
The toxicity value for vascular aquatic plants is based on a limit test using L. gibba and based on
the results of that test, the ECso is greater than the highest concentration tested, i.e., >900 ug/L.
With a peak EEC of 52.0 ug/L for vinclozolin residues of concern, the RQ is <0.058 and is
below the LOG of 1.0. As such, vinclozolin is not likely to indirectly affect the CRLF via
reduction in vascular plants. As discussed previously, none of the majority of aquatic
nonvascular plant species tested exhibited growth effects greater 8% at concentrations roughly
28 times higher than the maximum total toxic residues estimated for vinclozolin and its
degradates, vinclozolin is not likely to indirectly affect the CRLF via reduction in non-vascular
plants.
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5.1.2 Exposures in the Terrestrial Habitat
5.1.2.1 Direct Effects to Terrestrial-phase CRLF
As previously discussed in Section 3.3, potential direct effects to terrestrial-phase CRLFs are
based on ground applications of vinclozolin to turf grass.
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
and acute oral and subacute dietary toxicity endpoints for avian species. RQ values were not
calculated for acute and subacute exposures to the terrestrial-phase CRLF because: 1) vinclozolin
is practically nontoxic to birds on an acute oral (LD50>2,510 mg/kg bw) and subacute dietary
(LCso>5,620 mg/kg diet) toxicity basis; 2) there was no treatment related mortality and/or
sublethal effects at the highest treatment levels, and 3) EECs for the small bird consuming small
invertebrates are below the highest treatment levels of the acute oral and subacute dietary
toxicity tests. Therefore, risk of direct effects to terrestrial-phase CRLF is presumed low.
Potential direct chronic effects of vinclozolin 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. The NOAEC for
vinclozolin in bobwhite quail is 50 mg/kg diet and is based on reduced reproduction and based
on dietary EECs for small birds feeding on small insects, the RQ (9.09) exceeds the chronic risk
LOC(LOC>1.0).
Based on potential reproductive effects from chronic exposure, vinclozolin may affect the
terrestrial-phase of the CRLF.
5.1.2.2 Indirect Effects to Terrestrial-Phase CRLF via Reduction in Prey
(terrestrial invertebrates, mammals, and frogs)
Terrestrial Invertebrates
In order to assess the risks of vinclozolin to terrestrial invertebrates, which are considered prey of
CRLF in terrestrial habitats, the honeybee is used as a surrogate for terrestrial invertebrates.
EECs (jig a.i./g of bee) calculated by T-REX for small and large insects are 454 and 51 ppm (jig
a.i./g of bee), respectively. RQ values were not calculated for acute exposures to the terrestrial
invertebrates because: 1) vinclozolin is practically nontoxic to honey bees on an acute contact
basis (LD50>100 jig a.i. / bee or >781 jig a.i. / g of bee3); 2) there was no treatment related
mortality at the highest treatment level, and 3) EECs for terrestrial invertebrates are below the
highest treatment level of the acute contact test (where no mortality was observed). Therefore,
risk of effects to terrestrial invertebrates and subsequent indirect effects to the CRLF through
decrease in terrestrial invertebrate prey is presumed low.
! Based on the assumption that an adult honey bee weighs 0.128 g.
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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. RQ values were not calculated for acute exposures to small mammals
serving as prey to the CRLF because: 1) vinclozolin is practically nontoxic to mammals on an
oral (LD5o>10,000 mg/kg -bw) toxicity basis; 2) there was no treatment related mortality at the
highest treatment level, and 3) the acute, dose-based EEC for the small mammal consuming short
grass (770 mg/kg-bw) is below the highest treatment level of the acute oral test. Therefore, risk
of effects to small mammals exposed to vinclozolin on an acute oral basis and subsequent
indirect effects to the CRLF through decrease in terrestrial mammals is presumed low.
Chronic EECs are divided by the chronic toxicity values to estimate dose-based RQs as well as
dietary-based RQs. With a NOAEC of 30 mg/kg-day based on decreased reproduction, dose-
based (RQ=12) and dietary-based (RQ=2.7) RQ values exceed the chronic risk LOC (RQ>1.0).
Based on potential reproductive effects from chronic exposure, vinclozolin is likely to indirectly
affect the CRLF via reduction in small mammal prey items.
Frogs
An additional prey item of the adult terrestrial-phase CRLF is other species of frogs. In order to
assess risks to these organisms, dietary-based and dose-based exposures modeled in T-REX for a
small bird (20g) consuming small invertebrates are used. Direct acute effects on aquatic-phase
amphibians are not considered likely; however, direct chronic effects on aquatic-phase
amphibians may occur. As described in Section 5.2.1.2.1, direct chronic effects on terrestrial-
phase amphibians are also considered likely with a chronic RQ of 9.09. Based on the potential
chronic effects of vinclozolin on aquatic and terrestrial-phase amphibians that may serve as prey
for the CRLF, vinclozolin is likely to indirectly affect the CRLF via reduction in frogs as prey
items.
5.1.2.3 Indirect Effects to CRLF via Reduction in Terrestrial Plant
Community (Riparian and Upland Habitat)
Potential indirect effects to the CRLF resulting from direct effects on riparian and upland
vegetation are assessed using RQs from terrestrial plant seedling emergence and vegetative vigor
EC25 data as a screen. However, since no terrestrial plant toxicity data are available to assess the
potential effects of vinclozolin, RQ values could not be calculated. In the absence of data to the
contrary, it is conservatively assumed that vinclozolin is likely to indirectly affect the CRLF via
reduction in terrestrial plants.
5.1.3 Primary Constituent Elements of Designated Critical Habitat
For vinclozolin use, the assessment endpoints for designated critical habitat PCEs involve a
reduction and/or modification of food sources necessary for normal growth and viability of
aquatic-phase CRLFs, and/or a reduction and/or modification of food sources for terrestrial-
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phase juveniles and adults. Because these endpoints are also being assessed relative to the
potential for indirect effects to aquatic- and terrestrial-phase CRLF, the effects determinations
for indirect effects from the potential loss of food items are used as the basis of the effects
determination for potential modification to 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).
Acute and chronic RQ values for freshwater fish and invertebrates are below LOCs and there is a
low likelihood that vinclozolin may directly affect aquatic animals (Section 5.1.1.2). Although
risk estimates for effects to aquatic plants (Section 5.1.1.3) are below the LOG, there is
uncertainty regarding the potential effect of vinclozolin on riparian plants (Section 5.1.2.3).
Because there are no terrestrial plant data (surrogate for riparian vegetation) available for
vinclozolin the presumption is that the chemical is likely to affect aquatic-phase PCEs of
designated habitat related to potential effects on terrestrial plants.
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
vinclozolin on this PCE (i.e., alteration of food sources), acute and chronic freshwater fish and
invertebrate toxicity endpoints, as well endpoints for aquatic non-vascular plants are used as
measures of effects. RQs for these endpoints were calculated in Sections 5.1.1.1 and 5.1.1.2.
Acute and chronic RQ values for freshwater fish invertebrates are below LOCs and there is a low
likelihood that vinclozolin will affect aquatic animals. As such, vinclozolin is not likely to affect
aquatic-phase PCEs of designated habitat related to effects of alteration of other chemical
characteristics necessary for normal growth and viability of CRLFs and their food source.
5.1.3.2 Terrestrial-Phase (Upland Habitat and Dispersal Habitat)
The first two assessment endpoints for the terrestrial-phase PCEs of designated critical habitat
for the CRLF are related to potential effects to terrestrial plants:
• Elimination and/or disturbance of upland habitat; ability of habitat to support food source
of CRLFs: Upland areas within 200 ft of the edge of the riparian vegetation or dripline
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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 risk estimation for terrestrial-phase PCEs of designated habitat related to potential effects on
terrestrial plants is provided in Section 5.1.2.3. Since no data are available on the potential
effects of vinclozolin on terrestrial plants, the presumption is that vinclozolin is likely to affect
the first and second terrestrial - phase PCEs.
The third terrestrial-phase PCE is "reduction and/or modification of food sources for terrestrial
phase juveniles and adults." To assess the impact of vinclozolin 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. Although RQ values for
terrestrial invertebrates nominally exceed the LOG, no mortality occurred at the highest exposure
concentration tested (LD50>100 |ig/bee) and as such, risks to terrestrial invertebrates from the
use of vinclozolin on turf is considered low. Vinclozolin is practically nontoxic to birds and
mammals on an acute exposure basis and the likelihood of acute adverse effects in these animals
from the use of vinclozolin on turf is considered low; however, chronic reproductive effects in
birds, terrestrial-phase amphibians, and mammals are possible. Based on the potential for
chronic effects of vinclozolin on animals that may serve as prey for CRLF, vinclozolin is likely
to affect the third terrestrial - phase PCEs.
The fourth terrestrial-phase PC 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 5.2.1.21. Although the
likelihood of direct acute effects on terrestrial-phase CRLFs is considered low, direct chronic
effects are considered likely (RQ=9.09). Therefore, vinclozolin is likely to affect the forth
terrestrial - phase PCEs.
5.2 Risk Description
The risk description synthesizes an overall conclusion regarding the likelihood of adverse
impacts leading to an effects determination (i.e., "no effect," "may affect, but not likely to
adversely affect," or "likely to adversely affect") for the CRLF and its designated critical habitat.
Based on the RQs presented in the Risk Estimation (Section 5.1) a preliminary effects
determination is "may affect" for the CRLF and critical habitat. The direct 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
vinclozolin. A summary of the results of the risk estimation results are provided in Table 17 for
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direct and indirect effects to the CRLF and in Table 18 for the PCEs of designated critical
habitat for the CRLF.
Table 17. Risk Estimation Summary for Vinclozolin Direct and Indirect Effects to CRLF.
Assessment Endpoint
LOC
Exceedances
(Y/N)
Description of Results of Risk Estimation
Aquatic-Phase CRLF
(eggs, larvae, tadpoles, juveniles, and adults)
Direct Effects
Survival, growth, and reproduction of
CRLF individuals via direct effects on
aquatic phases
Indirect Effects
Survival, growth, and reproduction of
CRLF individuals via effects to food
supply (i.e., freshwater invertebrates,
non-vascular plants)
Indirect Effects
Survival, growth, and reproduction of
CRLF individuals via effects on
habitat, cover, and/or primary
productivity (i.e., aquatic plant
community)
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.
N
N
N
Y
Acute and chronic RQ values for fish are below LOCs.
Acute and chronic RQ values for freshwater invertebrates are
below the acute and chronic risk LOCs. Indirect effects on
aquatic -phase CRLF from effects on non-vascular aquatic
plants are not considered likely since RQ values for non-
vascular plants are below the LOC.
Available data indicate that vinclozolin is not likely to cause
adverse effects on the aquatic plant community.
There is uncertainty [due to the lack of data] regarding the
chemical's potential effect on terrestrial plants that provide
[riparian] cover for aquatic environment; therefore, risk is
presumed.
Terrestrial-Phase CRLF
(Juveniles and adults)
Direct Effects
Survival, growth, and reproduction of
CRLF individuals via direct effects on
terrestrial phase adults and juveniles
Indirect Effects
Survival, growth, and reproduction of
CRLF individuals via effects on prey
(i.e., terrestrial invertebrates, small
terrestrial mammals and terrestrial-
phase amphibians)
Indirect Effects
Survival, growth, and reproduction of
CRLF individuals via effects on
habitat (i.e., riparian vegetation)
Y
Y
Y
Although vinclozolin is practically nontoxic to terrestrial
animals on an acute exposure basis, chronic exposure may
adversely affect reproduction. The chronic RQ value exceeds
the chronic risk LOC by a factor of 9X.
Chronic RQ values for both small mammals and aquatic- and
terrestrial-phase amphibians serving as prey for CRLF exceed
the chronic risk LOC by factors as high as 12X (dose-based
RQ).
There is uncertainty regarding the chemical's potential effect
on terrestrial plants that provide [riparian] cover for aquatic
environment; therefore, risk is presumed.
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Table 18. Risk Estimation Summary for vinclozolin- PCEs of Designated Critical Habitat
for the CRLF.
Assessment Endpoint
LOG Exceedances
(Y/N)
Description of Results of Risk Estimation
Aquatic Phase PCEs
(Aquatic Breeding Habitat and Aquatic Non-Breeding Habitat)
Alteration of channel/pond morphology or
geometry and/or increase in sediment
deposition within the stream channel or
pond: aquatic habitat (including riparian
vegetation) provides for shelter, foraging,
predator avoidance, and aquatic dispersal
for juvenile and adult CRLFs.
Alteration in water chemistry/quality
including temperature, turbidity, and oxygen
content necessary for normal growth and
viability of juvenile and adult CRLFs and
their food source.
Alteration of other chemical characteristics
necessary for normal growth and viability of
CRLFs and their food source.
Reduction and/or modification of aquatic-
based food sources for pre-metamorphs
(e.g., algae)
Y
Y
N
N
There is uncertainty regarding the chemical's
potential effect on terrestrial plants that provide
[riparian] cover for aquatic environment; therefore,
risk is presumed.
There is uncertainty regarding the chemical's
potential effect on terrestrial plants that provide
[riparian] cover for aquatic environment; therefore,
risk is presumed.
Available data indicate that vinclozolin is not likely
to cause adverse effects on the aquatic plant or
animal community representing the prey of the
aquatic -phase CRLF.
Available data indicate that vinclozolin is not likely
to cause adverse effects on the aquatic plant
community.
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
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.
Y
Y
Y
Y
There is uncertainty regarding the chemical's
potential effect on terrestrial plants that provide
cover for terrestrial environment; therefore, risk is
presumed.
There is uncertainty regarding the chemical's
potential effect on terrestrial plants that provide
cover for terrestrial environment; therefore, risk is
presumed.
RQs exceed the LOG for chronic exposures of
small mammals and aquatic- and terrestrial-phase
amphibians to vinclozolin.
RQs exceed the LOG for chronic exposures of
small mammals and terrestrial-phase amphibians to
vinclozolin.
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Following a "may affect" determination, additional information is considered to refine the
potential for exposure at the predicted levels based on the life history characteristics (i.e., habitat
range, feeding preferences, etc.) of the CRLF. Based on the best available information, the
Agency uses the refined evaluation to distinguish those actions that "may affect, but are not
likely to adversely affect" from those actions that are "likely to adversely affect" the CRLF and
its designated critical habitat.
The criteria used to make determinations that the effects of an action are "not likely to adversely
affect" the CRLF and its designated critical habitat include the following:
• Significance of Effect: Insignificant effects are those that cannot be meaningfully
measured, detected, or evaluated in the context of a level of effect where "take" occurs
for even a single individual. "Take" in this context means to harass or harm, defined as
the following:
• Harm includes significant habitat modification or degradation that results in
death or injury to listed species by significantly impairing behavioral patterns
such as breeding, feeding, or sheltering.
• Harass is defined as actions that create the likelihood of injury to listed species
to such an extent as to significantly disrupt normal behavior patterns which
include, but are not limited to, breeding, feeding, or sheltering.
• Likelihood of the Effect Occurring: Discountable effects are those that are extremely
unlikely to occur.
• Adverse Nature of Effect: Effects that are wholly beneficial without any adverse effects
are not considered adverse.
A description of the risk and effects determination for each of the established assessment
endpoints for the CRLF and its designated critical habitat is provided in Sections 5.2.1 through
5.2.3.
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 vinclozolin.
Acute and chronic RQ values are below the LOCs for the aquatic-phase CRLF. The likelihood
of individual acute mortality is 1 in 4.86 xlO14 and there are no incident data to indicate that the
use of vinclozolin on turf in California is having a direct effect on aquatic-phase CRLF. Based
on the available information and the weight of evidence the potential direct impact to the
aquatic-phase of the CRLF based on acute mortality is considered low.
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5.2.1.2 Terrestrial-Phase CRLF
Based on the use of avian surrogate toxicity data, vinclozolin is characterized as practically
nontoxic to terrestrial-phase CRLF on an acute oral and sub-acute dietary exposure basis.
However, based on potential reproductive effects observed in bird studies following chronic
exposure, vinclozolin is likely to represent a chronic risk to terrestrial-phase amphibians. The
chronic RQ value exceeds the chronic risk LOG by a factor of 9X. In addition, dietary-based
chronic EECs generated by T-REX for the small bird consuming small insects exceed the
LOAEC of 125 mg/kg-diet, indicating that EECs are sufficient to exceed a level where
reproductive effects to birds were observed in the laboratory.
Evaluation of potential direct risk to the terrestrial-phase CRLF using the T-HERPS model
indicates that chronic, dietary-based RQs for CRLF consuming small and large insects and small
herbivore mammals exceed the LOG (1.0; Table 19).
Table 19. Chronic, dietary-based RQs for terrestrial-phase CRLF. RQs generated using T-
HERPS.
Food item
Small Insects
Large Insects
Small herbivore mammals
Small insectivore mammals
Small terrestrial phase amphibian
RQ
9.09
1.01
10.65
0.67
0.32
Even if vinclozolin use on turf was limited to a single application, the resulting RQ would
exceed the LOG by a factor of roughly 3.6X. The maximum single application rate would have
to be reduced by roughly 75% to 0.36 Ibs a.i./A for the RQ value to drop below the chronic risk
LOG for direct effects on the terrestrial-phase CRLF. Based on a single ground application of
vinclozolin at 1.35 Ibs a.i./A, the LOG for chronic effects to the terrestrial-phase CRLF is
exceeded up to 10 feet from the edge of the treatment field (determined using AgDRIFT Tier 1
ground model4, terrestrial assessment).
' Assuming a high boom and ASAE very fine to fine droplet size distribution.
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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. As discussed previously, the most sensitive
nonvascular aquatic plant is N. pelliculosa with an ECso < 1060 ug/L. Based on a peak EEC of
52.0 ug/L representing vinclozolin residues of concern, the RQ is >0.05. Since the aquatic plant
toxicity data are based on a limit test, the concentration required to result in an effect of 50% is
uncertain. As noted previously, none on the other aquatic non-vascular plants tested had effects
at treatment concentrations ranging between 0.87 - 1.02 mg a.i./L. The maximum effect on
these test species was less than 8%. Given that none of the other aquatic plant species tested
exhibited much of an effect at concentrations roughly 28 times higher than the maximum
residues estimated for vinclozolin and its degradates, vinclozolin is not likely to indirectly affect
the CRLF via reduction in non-vascular plants.
5.2.2.2 Aquatic Invertebrates
The potential for vinclozolin 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.
Based on the most sensitive endpoints for acute (48-hr ECso=4,000 ug/L) and chronic (790
ug/L), neither acute nor chronic RQ values exceed acute or chronic LOCs. As such, vinclozolin
use on turf in California is not expected to directly affect freshwater invertebrates that serve as
forage for aquatic-phase CRLF.
5.2.2.3 Fish and Aquatic-phase Frogs
Acute and chronic RQ values for fish and aquatic-phase frogs serving as prey for CRLF are
below the acute and chronic risk LOCs. No incidents have been reported for fish involving
either vinclozolin or its 3,5-DCA degradate. Although no monitoring data are available for
vinclozolin, there are data for the 3,5-DCA degradate. The peak value reported in NAWQA for
3,5-DCA in surface water is 0.0268 ug/L. If the DCA degradate is assumed to be as toxic as the
parent, i.e., acute LCso=2840 ug/L and chronic NOAEC=200 ug/L, then the acute and chronic
RQs based on monitoring data would be orders of magnitude <0.01. The weight-of-evidence
suggests that vinclozolin use on turf in California will have no effects on fish and aquatic-phase
amphibians serving as prey.
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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 indicated above, risk of effects to terrestrial invertebrates and
subsequent indirect effects to the CRLF through decrease in terrestrial invertebrate prey is
presumed low.
5.2.2.5 Mammals
Life history data for terrestrial-phase CRLFs indicate that large adult frogs consume terrestrial
vertebrates, including mice. Vinclozolin is practically nontoxic to mammals on an acute
exposure basis. Chronic exposure of mammals to vinclozolin at levels >30 mg/kg/day resulted
in decreased genital and reproductive tract malformations that in turn resulted in reproductive
failure (failure to sire offspring and these effects are believed to be consistent with the
chemical's ability to bind to the androgen receptor. These effects have served as a basis for the
endpoint (NOAEL=30 mg/kg/day) used to assess the potential chronic effects of vinclozolin on
mammalian prey items.
In order to not exceed the NOAEL of 30 mg/kg/day, the maximum single application rate of 1.35
Ibs a.i./A would have to be reduced to 0.25 Ibs a.i./A, which is a reduction of 81.5%. Based on a
single ground application of vinclozolin at 1.35 Ibs a.i./A, the LOG for chronic (dose based)
effects to small mammals consuming short grass is exceeded up to 12 feet from the edge of the
treatment field (determined using AgDRIFT Tier 1 ground model, terrestrial assessment).
Based on the above information, vinclozolin is likely to indirectly affect the CRLF through a
decrease in mammalian prey.
5.2.2.6 Terrestrial-phase Amphibians
Terrestrial-phase adult CRLFs also consume frogs. RQ values representing direct exposures of
vinclozolin to terrestrial-phase CRLFs are used to represent exposures of vinclozolin to frogs in
terrestrial habitats. Given the potential for effects to the terrestrial-phase CRLF resulting from
chronic exposures to vinclozolin, there is also potential for reproductive effects to terrestrial-
phase amphibians serving as prey to CRLF. Therefore, vinclozolin is likely to indirectly affect
the CRLF through a decrease in amphibian prey.
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5.2.3 Indirect Effects (via Habitat Effects)
5.2.3.1 Aquatic Plants (Vascular and Non-vascular)
Aquatic plants serve several important functions in aquatic ecosystems. Non-vascular aquatic
plants are primary producers and provide the autochthonous energy base for aquatic ecosystems.
Vascular plants provide structure as attachment sites and refugia for many aquatic invertebrates,
fish, and juvenile organisms, such as fish and frogs. In addition, vascular plants also provide
primary productivity and oxygen to the aquatic ecosystem. Rooted plants help reduce sediment
loading and provide stability to near-shore areas and lower stream banks. 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. Based
on a lack of LOG exceedances for nonvascular and vascular aquatic plants, indirect effects are
not expected to the aquatic-phase CRLF due to effects to aquatic plants in its habitat.
Due to terrestrial plant data (surrogate for riparian vegetation) exposed to vinclozolin, there is
uncertainty regarding the chemical's potential effect on riparian plants that provide cover for the
aquatic environment; therefore, risk is presumed. As a result, there is potential for indirect effects
to the CRLF due to effects to plants in its aquatic habitat.
5.2.3.2 Terrestrial Plants
Terrestrial plants serve several important habitat-related functions for the CRLF. In addition to
providing habitat and cover for invertebrate and vertebrate prey items of the CRLF, terrestrial
vegetation also provides shelter for the CRLF and cover from predators while foraging.
Terrestrial plants also provide energy to the terrestrial ecosystem through primary production.
Upland vegetation including grassland and woodlands provides cover during dispersal. Riparian
vegetation helps to maintain the integrity of aquatic systems by providing bank and thermal
stability, serving as a buffer to filter out sediment, nutrients, and contaminants before they reach
the watershed, and serving as an energy source.
Due to a lack of effects data for terrestrial plants exposed to vinclozolin, there is uncertainty
regarding the chemical's potential effect on terrestrial plants that provide cover for terrestrial
environment; therefore, risk is presumed. As a result, there is potential for indirect effects to the
CRLF due to effects to plants in its terrestrial habitat.
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:
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• Alteration of channel/pond morphology or geometry and/or increase in sediment
deposition within the stream channel or pond: aquatic habitat (including riparian
vegetation) provides for shelter, foraging, predator avoidance, and aquatic dispersal for
juvenile and adult CRLFs.
• Alteration in water chemistry/quality including temperature, turbidity, and oxygen
content necessary for normal growth and viability of juvenile and adult CRLFs and their
food source.
• Reduction and/or modification of aquatic-based food sources for pre-metamorphs (e.g.,
algae).
Conclusions for potential indirect effects to the CRLF via direct effects to aquatic and riparian
plants are used to determine whether modification to critical habitat may occur. Although effects
are not expected for nonvascular and vascular plants within the aquatic environment, due to lack
of terrestrial plant data (surrogate for riparian vegetation) exposed to vinclozolin, there is
uncertainty regarding the chemical's potential effect on riparian plants that are considered part of
the aquatic environment; therefore, risk is presumed. As a result, there is potential for there is
potential for effects to the aquatic-phase PCEs of the CRLF.
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, 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. Available data indicate that vinclozolin is not likely to cause adverse effects
on non-vascular plants, aquatic invertebrates or fish representing the prey of the aquatic-phase
CRLF.
5.2.4.2 Terrestrial-Phase PCEs
Two of the four assessment endpoints for the terrestrial-phase PCEs of designated critical habitat
for the CRLF are related to potential effects to terrestrial plants:
• Elimination and/or disturbance of upland habitat; ability of habitat to support food source
of CRLFs: Upland areas within 200 ft of the edge of the riparian vegetation or drip line
surrounding aquatic and riparian habitat that are comprised of grasslands, woodlands,
and/or wetland/riparian plant species that provides the CRLF shelter, forage, and predator
avoidance.
• Elimination and/or disturbance of dispersal habitat: Upland or riparian dispersal habitat
within designated units and between occupied locations within 0.7 mi of each other that
allow for movement between sites including both natural and altered sites which do not
contain barriers to dispersal.
There is uncertainty regarding the chemical's potential effect on terrestrial plants that provide
cover in the terrestrial habitat; therefore, risk is presumed. As a result, there is potential for there
is potential for effects to the terrestrial-phase PCEs of the CRLF.
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The third terrestrial-phase PCE is "reduction and/or modification of food sources for terrestrial
phase juveniles and adults." To assess the impact of vinclozolin on this PCE, acute and chronic
toxicity endpoints for terrestrial invertebrates, mammals, and terrestrial-phase frogs are used as
measures of effects. Due to LOG exceedances by chronic RQs for small mammals and
terrestrial-phase amphibians, there is potential for effects to this PCE.
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. Due to LOG
exceedances by chronic RQs for small mammals, terrestrial-phase amphibians, and terrestrial-
phase CRLFs, there is potential for effects to this PCE.
5.2.5 Addressing the Risk Hypotheses
In order to conclude this risk assessment, it is necessary to address the risk hypotheses defined in
Section 2.9.1. Based on the conclusions of this assessment, not all of the hypotheses can be
rejected, meaning that some of the hypotheses represent concerns in terms of direct and indirect
effects of vinclozolin on the CRLF and its designated critical habitat.
6.0 Uncertainties
6.1 Exposure Assessment Uncertainties
6.1.1 Maximum Use Scenario
The screening-level risk assessment focuses on characterizing potential ecological risks resulting
from a maximum use scenario, which is determined from labeled statements of maximum
application rate and number of applications with the shortest time interval between applications.
The frequency at which actual uses approach this maximum use scenario may be dependant on
pest resistance, timing of applications, cultural practices, and market forces.
6.1.2 Aquatic Exposure Modeling of Vinclozolin
The standard ecological water body scenario (EXAMS pond) used to calculate potential aquatic
exposure to pesticides is intended to represent conservative estimates, and to avoid
underestimations of the actual exposure. The standard scenario consists of application to a 10-
hectare field bordering a 1-hectare, 2-meter deep (20,000 m3) pond with no outlet. Exposure
estimates generated using the EXAMS pond are intended to be a surrogate for a wide variety of
vulnerable water bodies that occur at the top of watersheds including prairie pot holes, playa
lakes, wetlands, vernal pools, man-made and natural ponds, and intermittent and lower order
streams. As a group, there are factors that make these water bodies more or less vulnerable than
the EXAMS pond. Static water bodies that have larger ratios of pesticide-treated drainage area
to water body volume would be expected to have higher peak EECs than the EXAMS pond.
These water bodies will be either smaller in size or have larger drainage areas. Smaller water
bodies have limited storage capacity and thus may overflow and carry pesticide in the discharge,
whereas the EXAMS pond has no discharge. As watershed size increases beyond 10-hectares, it
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becomes increasingly unlikely that the entire watershed is planted with a single crop that is all
treated simultaneously with the pesticide. Headwater streams can also have peak concentrations
higher than the EXAMS pond, but they likely persist for only short periods of time and are then
carried and dissipated downstream.
The Agency acknowledges that there are some unique aquatic habitats that are not accurately
captured by this modeling scenario and modeling results may, therefore, under- or over-estimate
exposure, depending on a number of variables. For example, aquatic-phase CRLFs may inhabit
water bodies of different size and depth and/or are located adjacent to larger or smaller drainage
areas than the EXAMS pond. The Agency does not currently have sufficient information
regarding the hydrology of these aquatic habitats to develop a specific alternate scenario for the
CRLF. CRLFs prefer habitat with perennial (present year-round) or near-perennial water and do
not frequently inhabit vernal (temporary) pools because conditions in these habitats are generally
not suitable (Hayes and Jennings 1988). Therefore, the EXAMS pond is assumed to be
representative of exposure to aquatic-phase CRLFs. In addition, the Services agree that the
existing EXAMS 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.
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
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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.
6.1.3 Total residues of concern
Metabolites B and E and 3,5-DCA, which are major degradates of vinclozolin, are considered to
be residues of concern. Metabolite S also appears in 1 study (soil photolysis) as a major
degradate. This degradate is similar in structure to vinclozolin and may be assumed to share a
mode of action with vinclozolin, metabolite B and metabolite E; however, since this degradate
appears as a major degradate only in the available soil photolysis study, which is not used to
parameterize PRZM/EXAMS, this metabolite is not does not affect half-lives to represent total
residues of concern for vinclozolin. In addition, Metabolite F, which appears in the fish
bioconcentration study as a major degradate is not considered in calculating half-lives to
represent total residues of concern for vinclozolin. This is also because the fish bioconcentration
study is not used to parameterize PRZM/EXAMS. Since Metabolites S and F appear in
environmental fate studies that do not affect the parameterization of the environmental fate
models (i.e., PRZM/EXAMS), their presence does not alter the estimation of environmental
concentrations of vinclozolin residues of concern.
The total residue of concern method is used to provide a conservative estimate of exposure of
aquatic organisms to vinclozolin's residues of concern. There is some uncertainty in this
approach, since conservative half-lives were used to represent the persistence of vinclozolin
residues of concern in the environment. Also, it was assumed that the toxicities of vinclozolin's
residues are equivalent to that of the parent. In order to characterize the uncertainty associated
with these assumptions, aquatic EECs were derived for vinclozolin alone using half-lives
specific to vinclozolin. The resulting EECs for vinclozolin (Appendix D) are an order of
magnitude lower than the EECs for vinclozolin residues of concern.
6.1.3 Measured concentrations of 3,5-DCA in surface water
The maximum concentration of 3,5-DCA reported by NAWQA for California surface waters is
0.03 |ig/L. This value is approximately 3 orders of magnitude lower the maximum model-
estimated environmental concentration for 3,5-DCA (Appendix D). There is uncertainty
regarding the source of the measured 3,5-DCA as it could be attributed to use of vinclozolin or
iprodione.
6.1.5 Usage Uncertainties
County-level usage data were obtained from California's Department of Pesticide Regulation
Pesticide Use Reporting (CDPR PUR) database. Eight years of data (1999-2006) were included
in this analysis because statistical methodology for identifying outliers, in terms of area treated
and pounds applied, was provided by CDPR for these years only. 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
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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.
6.1.6 Terrestrial Exposure Modeling of Vinclozolin
The Agency relies on the work of Fletcher et al. (1994) for setting the assumed pesticide residues
in wildlife dietary items. These residue assumptions are believed to reflect a realistic upper-
bound residue estimate, although the degree to which this assumption reflects a specific
percentile estimate is difficult to quantify. It is important to note that the field measurement
efforts used to develop the Fletcher estimates of exposure involve highly varied sampling
techniques. It is entirely possible that much of these data reflect residues averaged over entire
above ground plants in the case of grass and forage sampling.
It was assumed that ingestion of food items in the field occurs at rates commensurate with those
in the laboratory. Although the screening assessment process adjusts dry-weight estimates of
food intake to reflect the increased mass in fresh-weight wildlife food intake estimates, it does
not allow for gross energy differences. Direct comparison of a laboratory dietary concentration-
based effects threshold to a fresh-weight pesticide residue estimate would result in an
underestimation of field exposure by food consumption by a factor of 1.25 - 2.5 for most food
items.
Differences in assimilative efficiency between laboratory and wild diets suggest that current
screening assessment methods do not account for a potentially important aspect of food
requirements. Depending upon species and dietary matrix, bird assimilation of wild diet energy
ranges from 23 - 80%, and mammal's assimilation ranges from 41 - 85% (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.
6.1.7 Spray Drift Modeling
Although there may be multiple vinclozolin applications at a single site, it is unlikely that the
same organism would be exposed to the maximum amount of spray drift from every application
made. In order for an organism to receive the maximum concentration of vinclozolin from
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multiple applications, each application of vinclozolin would have to occur under identical
atmospheric conditions (e.g., same wind speed and - for plants - same wind direction) and (if it
is an animal) the animal being exposed would have to be present directly downwind at the same
distance after each application. Although there may be sites where the dominant wind direction
is fairly consistent (at least during the relatively quiescent conditions that are most favorable for
aerial spray applications), it is nevertheless highly unlikely that plants in any specific area would
receive the maximum amount of spray drift repeatedly. It appears that in most areas (based upon
available meteorological data) wind direction is temporally very changeable, even within the
same day. Additionally, other factors, including variations in topography, cover, and
meteorological conditions over the transport distance are not accounted for by the AgDRIFT
model (i.e., it models spray drift from aerial and ground applications in a flat area with little to
no ground cover and a steady, constant wind speed and direction). Therefore, in most cases, the
drift estimates from AgDRIFT may overestimate exposure even from single applications,
especially as the distance increases from the site of application, since the model does not account
for potential obstructions (e.g., large hills, berms, buildings, trees, etc.). Furthermore,
conservative assumptions are made regarding the droplet size distributions being modeled
('ASAE Very Fine to Fine'), the application method, release heights (high boom) and wind
speeds. Alterations in any of these inputs would change the area of potential effect.
6.2 Effects Assessment Uncertainties
6.2.1 Age Class and Sensitivity of Effects Thresholds
It is generally recognized that test organism age may have a significant impact on the observed
sensitivity to a toxicant. The acute toxicity data for fish are collected on juvenile fish between
0.1 and 5 grams. Aquatic invertebrate acute testing is performed on recommended immature age
classes (e.g., first instar for daphnids, second instar for amphipods, stoneflies, mayflies, and third
instar for midges).
Testing of juveniles may overestimate toxicity at older age classes for pesticide active
ingredients that act directly without metabolic transformation because younger age classes may
not have the enzymatic systems associated with detoxifying xenobiotics. In so far as the
available toxicity data may provide ranges of sensitivity information with respect to age class,
this assessment uses the most sensitive life-stage information as measures of effect for surrogate
aquatic animals, and is therefore, considered as protective of the CRLF.
6.2.2 Use of Surrogate Species Effects Data
Guideline toxicity tests and open literature data on vinclozolin and its degradates 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
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phyla. In addition, the Agency's LOCs are intentionally set very low, and conservative estimates
are made in the screening level risk assessment to account for these uncertainties.
6.2.3 Sublethal Effects
When assessing acute risk, the screening risk assessment relies on the acute mortality endpoint as
well as a suite of sublethal responses to the pesticide, as determined by the testing of species
response to chronic exposure conditions and subsequent chronic risk assessment. Consideration
of additional sublethal data in the effects determination is exercised on a case-by-case basis and
only after careful consideration of the nature of the sublethal effect measured and the extent and
quality of available data to support establishing a plausible relationship between the measure of
effect (sublethal endpoint) and the assessment endpoints. However, the full suite of sublethal
effects from valid open literature studies is considered for the purposes of defining the action
area.
Since 3,5-DCA is classified as a potential carcinogen and given the androgen receptor binding
capacity of vinclozolin Metabolite B and E, there are a broad range of sublethal effects that could
be associated with vinclozolin. The reproductive effects exhibited across a broad range of taxa
indicate that the effects of vinclozolin on endocrine-mediated process are not limited to specific
animals. This assessment has attempted to account for sublethal effects by setting the initial area
of concern as the entire State of California. To the extent to which sublethal effects are not
considered in this assessment, the potential direct and indirect effects of vinclozolin 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 Potential Effects to Terrestrial and Riparian Plants
As indicated above, no data are available to characterize the effects of vinclozolin on terrestrial
and riparian plants. Therefore, the risks to these plants from the use of vinclozolin on turf grass is
unknown. Since risk cannot be precluded, this assessment concludes that use of vinclozolin on
turf can result in modification of the CRLF's critical habitat. It should be noted that the lack of
terrestrial plant data renders the risk conclusions for habitat modification highly uncertain.
6.2.6 Toxicities of Vinclozolin Degradates
At this time, limited toxicity data are available to characterize the effects of metabolites with
structures similar to that of the parent or 3,5-DCA to non-target organisms. Therefore, it is
assumed that data available for vinclozolin are representative of effects to non-target organisms
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that may be caused by metabolites similarly structured degradates. If the toxicity of vinclozolin
is different than that of metabolites B and E, the effects of vinclozolin may be under- or over-
estimated. However, the extent to which this may be the case is unknown.
Limited toxicity data are available for 3,5-DCA that suggest that the compound is less toxic than
the parent and it is assumed that this chemical has a different mode of action compared to
vinclozolin; however, because only limited data are available, this assessment conservatively
assumes that 3,5-DCA is as toxic as the parent to non-target organisms.
7.0 Risk Conclusions
In fulfilling its obligations under Section 7(a)(2) of the Endangered Species Act, the information
presented in this endangered species risk assessment represents the best data currently available
to assess the potential risks of vinclozolin 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 vinclozolin on turf in California. The Agency has
determined that there is the potential for modification of CRLF designated critical habitat from
the single use of the chemical on turf. Based on chronic direct effects on the terrestrial-phase
CRLF and indirect effects on both the aquatic-phase and terrestrial-phase CRLF due to chronic
effects on prey items, the use of vinclozolin on turf in California is considered likely to adversely
affect the CRLF. Additionally, there is uncertainty regarding the potential effects of vinclozolin
on terrestrial plants because of the lack of terrestrial plant toxicity data and because of this
uncertainty, the use of vinclozolin may result in habitat modification. Given the LAA
determination for the CRLF and uncertainty regarding the potential modification of designated
critical habitat, a description of the baseline status and cumulative effects for the CRLF is
provided in Attachment II.
The LAA effects determination applies to those areas where it is expected that the pesticide's use
will directly or indirectly affect the CRLF or its designated critical habitat. To determine this
area, the footprint of vinclozolin's use pattern is identified, using land cover data that correspond
to vinclozolin's use on turf grass. The spatial extent of the LAA effects determination also
includes areas beyond the initial area of concern that may be impacted by runoff and/or spray
drift. The identified direct and indirect effects and modification to critical habitat are anticipated
to occur only for those currently occupied core habitat areas, CNDDB occurrence sections, and
designated critical habitat for the CRLF that overlap with the initial area of concern plus 12 feet
from its boundary (based on risks of chronic exposures to small mammals serving as prey to the
terrestrial-phase CRLF; refer to Section 5.2.2.5).
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 Table 20 and Table 21.
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Table 20. Effects Determination Summary for Vinclozolin Use and the CRLF.
Assessment
Endpoint
Effects
Determination
Basis for Determination
Survival, growth,
and/or reproduction
of CRLF
individuals
May affect,
likely to
adversely affect
(LAA)
Potential for Direct Effects
Aquatic-phase (Eggs, Larvae, and Adults):
Based on available data, both acute and chronic RQ values are below acute and
chronic risk LOCs. As such, vinclozolin use on turf is determined to have no
direct effect on aquatic-phase CRLF.
Terrestrial-phase (Juveniles and Adults):
Although vinclozolin is considered practically nontoxic to terrestrial-phase
amphibians (based on avian data used as a surrogate) on an acute oral and sub-
acute dietary exposure basis, chronic RQs based on impaired reproduction
exceed the chronic risk LOG by a factor of 9X. EECs are also sufficient to
exceed the level where reproductive effects were observed in birds (the LOAEC).
As such, the use of vinclozolin on turf grass in California is determined to be
likely to adversely affect terrestrial-phase CRLF due to direct chronic effects on
reproduction.
Potential for Indirect Effects
Aquatic prey items, aquatic habitat, cover and/or primary productivity
Acute and chronic RQ values are below the acute and chronic risk LOCs for
freshwater invertebrates. RQ values for non-vascular and vascular aquatic plants
are below the LOG and/or vinclozolin is not expected to adversely affect the
aquatic plant community. Given that vinclozolin does not directly affect aquatic
vertebrates, vinclozolin is determined to have no effect on fish and aquatic-phase
amphibians that serve as prey for CRLF.
Terrestrial prey items, riparian habitat
Although vinclozolin is practically nontoxic to terrestrial-phase amphibians and
mammals on an acute exposure basis, chronic RQs based on impaired
reproduction exceed the chronic risk LOG by a factor of 9X for terrestrial-phase
amphibians and factors as high as 12X for small mammals that serve as prey for
CRLF. In addition, because of uncertainty regarding the potential effects of
vinclozolin on terrestrial plants, risk is presumed for the riparian habitat on
which CRLF depend. As such, the use of vinclozolin on turf in California is
determined to be likely to adversely affect the CRLF through indirect effects on
prey and habitat.
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Table 21. Effects Determination Summary for Vinclozolin Use and CRLF Critical Habitat
Impact Analysis.
Assessment
Endpoint
Effects
Determination
Basis for Determination
Modification of
aquatic-phase PCE
Modification of
terrestrial-phase
PCE
Habitat
Modification
Based on the weight of evidence, the use of vinclozolin on turf grass in
California is determined to have no adverse effect on aquatic plants; however,
there is uncertainty regarding the potential effects of vinclozolin on terrestrial
plants because of the absence of terrestrial plant toxicity data. Because of this
uncertainty, risk is presumed and there is a potential for habitat modification due
to effects on riparian cover surrounding aquatic areas.
There is uncertainty regarding the potential effects of vinclozolin on terrestrial
plants because of the absence of data. Because of this uncertainty, risk is
presumed and there is a potential for habitat modification due to effects on
riparian cover.
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
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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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Alvarez, J. 2000. Letter to the U.S. Fish and Wildlife Service providing comments on the Draft
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Anderson, S.; Clark, J. (1993) RONILAN Fungicide (BAS 352 12F) Soil Dissipation in Orchard
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