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UNITED STATES ENVIRONMENTAL PROTECTION AGENCY
WASHINGTON, D.C. 20460
June 26, 2019
OFFICE OF CHEMICAL SAFETY
AND POLLUTION PREVENTION
MEMORANDUM
PC Code:061601
DP Barcode: 430829
SUBJECT:
FROM:
THRU:
Paraquat: Preliminary Ecological Risk Assessment for Registration Review
DONNA JUDKINS
2019.06.26
13:01:22-04W
Donna R.Judkins, Biologist
Stephen P. Wente, Senior Scientist Wente, Stephen!
Environmental Risk Branch II
Environmental Fate and Effects Division (7507P)
Lin, James
Digitally signed by
Lin, James
Date: 2019.06.26
13:16:05 -04'00"
Digitally signed by Arnold, Elyssa
Date: 2019.06.26 13:21:33 -04'00'
James Lin, Environmental Engineer
Melissa Panger, Senior Science Advisor
Elyssa Arnold, Senior Biologist
Elizabeth Donavan, Acting Risk Assessment Process Leader
Melanie Biscoe, Acting Branch Chief MELANIE
Environmental Risk Branch II BISCOE
Environmental Fate and Effects Division (7507P)
Digitally signed by
MELANIE BISCOE
Date: 2019.06.27
09:56:57 -04'00'
DONOVAN
Digitally signed by
ELIZABETH DONOVAN
Date: 2019.06.27 08:16:29
-04W
TO: Marianne Mannix, Chemical Review Manager
Carolyn Schroeder, Team Leader
Kelly Sherman, Branch Chief
Risk Management and Implementation Branch 3
Pesticide Re-evaluation Division (7508P)
The Environmental Fate and Effects Division (EFED) has completed the preliminary
environmental fate and ecological risk assessment in support of the Registration Review of the
herbicide paraquat dichloride, chiefly as its dissociated cation paraquat. All the major
taxonomic groups are assessed to re-evaluate primary risk concerns. This assessment
concluded that all registered uses of paraquat pose a potential for direct adverse effects to
birds, terrestrial-phase amphibians, reptiles, terrestrial plants, and aquatic plants, and to a
lesser degree, to mammals, pollinators, fish, and benthic invertebrates. The pollinator
assessment is incomplete pending receipt of the larval and chronic adult toxicity data.
-------
Preliminary Ecological Risk Assessment for the
Registration Review of Paraquat
2C1-
Paraquat; CAS No 1910-42-5
USEPA PC Code: 061601
Prepared by:
Donna R.Judkins, Ph.D., Biologist
Stephen P. Wente, Ph.D., Senior Scientist
Reviewed by:
James Lin, Ph.D., Environmental Engineer
Melissa Panger, Ph.D. Senior Science Advisor
Elyssa Arnold, Senior Biologist
Approved by:
Elizabeth Donovan, Acting Risk Assessment Process Leader
Melanie Biscoe, Acting Branch Chief
Environmental Risk Branch II
Environmental Fate and Effects Division
Office of Pesticide Programs
United States Environmental Protection Agency
June 26, 2019
1
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Table of Contents
1 Executive Summary 4
1.1 Overview 4
1.2 Risk Conclusions Summary 4
1.3 Environmental Fate and Exposure Summary 7
1.4 Ecological Effects Summary 8
1.5 Identification of Data Needs 8
2 Introduction 3
3 Problem Formulation Update [[[ 9
3.1 Mode of Action for Target Pests 10
3.2 Label and Use Characterization 11
3.2.1 Label Summary 11
3.2.2 Usage Summary 13
4 Residues of Concern[[[ 14
5 Environmental Fate Summary[[[ 14
6 Ecotoxicity Summary[[[ 16
6.1 Aquatic Toxicity 17
6.2 Terrestrial Toxicity 21
6.3 Incident Data 25
7 Analysis Plan[[[ 31
7.1 Overall Process 31
7.1.1 Listed Species 32
7.1.2 Endocrine Disruptor Screening Program (EDSP) 33
7.2 Modeling 34
8 Aquatic Organisms Risk Assessment[[[ 35
8.1 Aquatic Exposure Assessment 35
8.1.1 Modeling 35
8.1.2 Monitoring 44
8.2 Aquatic Organism Risk Characterization 46
8.2.1 Aquatic Vertebrates 46
8.2.2 Aquatic Invertebrates 48
8.2.3 Aquatic Plants 52
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10.3.2 Tier I Risk Estimation (Oral Exposure) 70
10.4 Terrestrial Invertebrate Risk Characterization - Additional Lines of Evidence 73
11 Terrestrial Plant Risk Assessment74
11.1 Terrestrial Plant Exposure Assessment 74
11.2 Terrestrial Plant Risk Characterization 75
12 Conclusions 77
13 Literature Cited77
14 Referenced MRIDs 81
Appendix A. ROCKs table[[[ 106
Append! ample Aquatic Modeling Output 140
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1 Executive Summary
1.1 Overview
This Preliminary Risk Assessment (PRA) examines the potential ecological risks associated with
labeled uses of paraquat on non-listed non-target organisms. All the major taxonomic groups
are assessed to re-evaluate primary risk concerns even though previously completed risk
assessments identified plants and terrestrial vertebrates as the chief taxa at risk. Risk to aquatic
species was evaluated because of the availability of a more complete toxicity data set for
benthic invertebrates, and for chronic effects to aquatic species. The exception to a complete
data set is additional bee studies, which were not requested when the problem formulation
(USEPA, 2011a) was written, but are needed now to complete the bee assessment following
current guidance (USEPA et al., 2014).
The active ingredient, paraquat dichloride, is a quaternary ammonium compound widely used
for broadleaf weed control on agricultural, forestry, residential, commercial, and nursery use
sites. It is a fast-acting contact herbicide used to suppress or eradicate a wide spectrum of post-
emergent weeds and is quickly absorbed by living plant tissue. It is generally applied as a
flowable solution and readily dissociates into its cation, paraquat, which is the only stressor of
concern (refer to Appendix A for structure and degradates).
1.2 Risk Conclusions Summary
Overall Conclusions:
• Paraquat rapidly and almost completely adsorbs to soil and/or sediment, which greatly
limits the types of environmental exposures expected from paraquat applications.
• Laboratory fate studies did not detect degradation of paraquat, indicating that it is very
persistent in soil/sediment and accumulates in the environment in an adsorbed state.
• It is largely unknown when or if paraquat applications might exceed the adsorptive
capacities of the soil/sediment and whether or how fast the excess paraquat would
metabolize in the environment.
• Risk conclusions are similar to those previously identified. The main risk drivers are:
o birds (also terrestrial-phase amphibians and reptiles; incidents have involved
bird deaths; application timing may be important to reduce reproductive
effects),
o plants (up to 17 feet from application site or 14 feet using coarse droplets), and
o aquatic plants (algae more sensitive than aquatic vascular plants).
• Other taxonomic groups at risk are:
o mammals (at risk, but less sensitive than birds; incidents have involved dogs),
o bees (adult acute risk due to oral exposure despite low oral toxicity; no contact
risk; chronic and larval risks unknown),
4
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o fish (based on incident information; 4 fish-kills possibly resulting from aquatic
plant die-offs), and
o benthic aquatic invertebrates.
Table 1-1. Summary of Risk Quotients for Taxonomic Groups from Current Uses of Paraquat.
Taxa
Exposure
Risk
Quotient
RQ
Exceeding
the LOC for
Non-listed
Species
Additional Information/
Duration
(RQ)
Lines of Evidence
Range1
Although not indicated by the RQs, there is a potential risk to
Freshwater
fish
Acute
<0.01
No
fish based on the available incident data. Paraquat is suspected
of being the primary cause in four fish-kills, suggesting potential
for harm to non-target aquatic animals. This may result from
Chronic
<0.01-0.012
No
dissolved oxygen sinks due to aquatic plant die-offs. Also, there
Acute
<0.01
No
is some suggestion of more sensitive fish and aquatic-phase
Estuarine/
marine fish
amphibian species. Overall, risk to fish and aquatic-phase
Chronic
<0.01}2
No
amphibians from the use of paraquat is uncertain but cannot be
precluded due to fish-kill incidents and the longevity of
paraquat.
Freshwater
Acute
<0.01
No
invertebrates
Chronic
<12
No
<0.01
Risk to aquatic invertebrates from water column exposure is
Estuarine/
marine
invertebrates
Acute
(Mollusks)
<0.01-
0.046
(Crustacea)
No
expected to be low, although there is some suggestion of more
sensitive crustacean species.
Chronic
<12
No
Acute
Paraquat's longevity and tendency to adsorb required different
and Sub-
<0.52
No
assumptions in modeling than usually used. Overall, risk to
Chronic
benthic organisms was low from short-term sediment exposure
Benthic
invertebrates
(representing both acute and 21-day time-frame). However,
Chronic
when paraquat is allowed to accumulate overtime (30-year
(Long-
term)
0.07-5.02
Yes
exposure estimate), estimated amounts show risk to benthic
organisms based on the 1.01 lb cation/A application rate; risk
would be 50% higher based on the higher rate of 1.5 lb cation/A.
Risks exceeding the LOC for all uses, based on multiple
applications; risks exceeding the LOC for most uses (1.01 lb/A
Acute
<0.01-6.6
Yes
rate) from a single application only for grass and broadleaf plant
consumers. Two dog incidents show potential for mortality, but
link to registered use not clearly substantiated.
0.04-81
Rat chronic reproduction study had no effects at the dietary
Mammals
using
level tested. Because that level was below estimated exposure
repro. data
(0.15-609
levels, an additional line-of-evidence was investigated by
estimating risk using prenatal growth data, which showed risk
Chronic
estimates
using
prenatal
growth
data)
Yes
above the LOC for all uses. Additional chronic data would not
likely change the risk conclusion. Application timing may be
important to reduce likelihood of reproduction effects and for
plant-eaters, the desiccating action of paraquat may reduce
palatability and decrease chronic exposure.
5
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Taxa
Exposure
Duration
Risk
Quotient
(RQ)
Range1
RQ
Exceeding
the LOC for
Non-listed
Species
Additional Information/
Lines of Evidence
Birds
Acute
0.01-57
Yes
Risks exceeding the LOC for all uses and for the lowest single
application rate by up to 10 times for small birds feeding on
short grass.
Six bird incidents show potential for mortality, but link to
registered use not made in five. One incident was confirmed to
be from a registered use.
Chronic
0.26-4.1
Yes
Risks exceeding the LOC for all uses and for the lowest single
application rate except for fruit/pod/seed-eaters. Effects include
decreased reproduction and food consumption; application
timing may be important to reduce likelihood of reproduction
effects and for plant-eaters, the desiccating action of paraquat
may reduce palatability and decrease chronic exposure.
Terrestrial
invertebrates
Acute
Adult
0.01-2.2
Yes
Oral exposure risks exceeding the LOC for all uses and for the
lowest single application rate for two honey bee castes. Contact
exposure risks not exceeding the LOC for any uses. Multiple uses
have the potential to attract pollinators, but application timing,
as well as distances of 7-46 feet, coarse droplet size
specifications can remove the presumption of risk to adult bees
from acute contact exposure from spray drift. One hive damage
incident was of 'possible' causality but of 'undetermined'
legality, suggesting potential for harm to pollinators but link to
registered use not clearly substantiated. More information is
needed to fully assess risks to bees.
Chronic
Adult
No data
No data
Acute
Larval
No data
No data
Chronic
Larval
No data
No data
Aquatic
plants
N/A
0.02-26
Yes for
Algae
Risk exceeding LOC for non-vascular species (based on the
freshwater diatom) for all uses and for the lowest application
rates; no LOC exceedances for vascular plants.
Terrestrial
plants
N/A
0.2-3.6
Yes
Risks from spray drift exceeding the LOC for all uses at the
lowest application rate for aerial application. Monocots and
dicots similarly sensitive to paraquat; effects to growth seen at
an order-of-magnitude lower exposure levels than survival and
emergence. Twenty-seven plant incidents found, with paraquat
as 'probable' or 'highly probable' cause in ten, support potential
for harm to plants from registered use of paraquat. Distances of
up to 17 feet were estimated to remove the presumption of risk
from aerial applications.
Level of Concern (LOC) Definitions: Terrestrial Animals: Acute=0.5; Chronic=1.0; Terrestrial invertebrates=0.4;
Aquatic Animals: Acute=0.5; Chronic=1.0; Plants: 1.0.
1 RQs reflect exposure estimates for paraquat and maximum application rates allowed on labels.
2 Due to the non-standard timeframe for estimating chronic exposure, these estimates are not considered to be
standard RQs, but estimated exposure: toxicity ratios.
Uncertainties with Toxicity Data:
• Plant toxicity data had some minor uncertainties: for the endpoint used for monocot
seedling emergence (oat), some variability seen in survival and emergence in mid-range
treatments was not considered treatment related, although some uncertainty is
acknowledged.
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• The rat reproduction endpoint used for chronic risk estimation showed no effects at the
same dietary concentration causing reproduction effects to birds (mallard). That level
was below estimated exposure levels so risk quotients have some uncertainty, and
chronic risk could not be precluded. Additional information, however, would not likely
change the risk conclusions because acute risk to mammals was concluded for all
registered uses. Also, an additional line-of-evidence was investigated by estimating risk
using rat prenatal growth data, which showed chronic risk above the LOC for all uses.
• In sub-chronic sediment toxicity studies, Crustacea (freshwater amphipod), were more
sensitive than insect larvae (midge); however, the midge was the only taxon for which
chronic sediment toxicity data were available. Due to the persistence of paraquat,
effects of long-term exposure of benthic organisms is largely unknown, especially via
ingestion of sediment-bound paraquat; however, a chronic freshwater amphipod study
would not likely provide sufficient information to change risk conclusions due to the
difficulties in assessing exposure.
• The daphnid acute and freshwater fish chronic studies used for risk calculations had
some minor uncertainties due to variability in the mid-range treatments.
• Information from the open literature suggests that some crustacean, fish, and
amphibian species may be more sensitive than the endpoints for which quantitatively
usable toxicity data were available.
Uncertainties with Modeling Estimates:
• With its longevity, potential for paraquat presence in many places in the environment is
not easily characterized.
• Several labels did not specify the re-application interval, so a 7-day interval was
conservatively assumed for exposure estimates.
• There is little fate data available to characterize how paraquat behaves in the
environment after soil or sediment adsorption sites become saturated. Based solely on
its lack of halogenation and absence of complex ring structures, it is reasonable to infer
that any bioavailable (non-adsorbed) paraquat would be readily metabolized.
13 Environmental Fate and Exposure Summary
Paraquat rapidly and strongly adsorbs to soil or sediments rather than degrading under
environmental conditions. Essentially, the adsorption of paraquat to soil/sediment is so much
faster than the microbial degradation of paraquat that degradation of paraquat was not
observed in the laboratory metabolism studies. Also, the adsorption in the adsorption-
desorption studies was so strong that no paraquat could be detected in the water phase of
these studies making it mathematically impossible to calculate reliable soil/water partition
coefficients (Kd). Therefore, aquatic environmental exposure estimates to paraquat have a high
degree of uncertainty. However, based on the properties of paraquat observed it is likely that:
1) terrestrial exposures would occur on avian and mammalian food items as normally assessed
by the Agency; and 2) aquatic exposures would occur through spray drift immediately after a
drift event (acute exposure), but would be unlikely to remain in a bioavailable state long
7
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enough for a chronic aquatic exposure in the water column. However, since some benthic
organisms recycle contaminants by ingesting contaminated sediment and excreting the
contaminants back on the surficial layer, conservative exposure estimates (sediment
concentrations) are provided for this exposure route (though it is uncertain how much of the
adsorbed paraquat might be released in the gut of any particular species of benthic organism).
1.4 Ecological Effects Summary
The ecological effects toxicity dataset is fairly complete, with the exception of a data gap for
pollinator toxicity. No chronic adult toxicity data or larval toxicity data were available, so the
risks associated with these effects could not be calculated.
Available data indicate that paraquat is moderately toxic to freshwater fish but less toxic to
estuarine/marine fish on an acute exposure basis. However, on a chronic exposure basis, the
freshwater and saltwater fish endpoints were closer. Paraquat is slightly-to-highly toxic to
aquatic invertebrates: moderately toxic to freshwater Crustacea, slightly toxic to
estuarine/marine mollusks, and highly toxic to estuarine/marine Crustacea on an acute
exposure basis. Estuarine/marine Crustacea were also more sensitive than freshwater Crustacea
on a chronic exposure basis. However, for benthic invertebrates, a freshwater amphipod
(Hyalella) was more sensitive than a marine amphipod and a freshwater midge.
Paraquat ranges from moderately toxic to highly toxic to three species of birds, including
passerines, and is moderately toxic to mammals on an acute oral exposure basis. Chronic data
with birds show effects to reproduction and food consumption; no effects were seen in
mammals at similar dietary exposure. Paraquat is practically non-toxic to young adult honey
bees on an acute (both contact and oral) exposure basis. Data are not available on the chronic
toxicity to adult honey bees or acute and chronic toxicity to larval honey bees. These data are
needed to fully assess potential risks to bees.
Available data for terrestrial plants exposed to formulated products containing between 19.2
and 22.4% cation indicated similar sensitivity between monocots and dicots. Paraquat
application to foliage resulted in growth effects at treatment levels more than an order-of-
magnitude lower than levels causing survival and emergence effects to seeds in treated soils.
This is consistent with paraquat's mode of action (see Section 3.1) in that it tends to cause plant
damage via rapid absorption and locosystemic influence.
1.5 Identification of Data Needs
The full suite of pollinator studies listed below have not been submitted. The higher tier studies
are only needed if Tier I results indicate risk concerns and data needs are identified by risk
managers. Based on unlikely presence of paraquat in pollen, the full suite may not be needed.
• Terrestrial invertebrate studies:
o Non-guideline (Tier 1): Honey bee adult acute oral toxicity
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o Non-guideline (Tier 1): Honey bee larvae acute toxicity
o Non-guideline (Tier 1): Honey bee adult chronic oral toxicity
o Non-guideline (Tier 1): Honey bee larvae chronic toxicity
o Non-guideline (Tier 2): Semi-field testing for pollinators (tunnel or colony feeding
studies)
o Non-guideline (Tier 2): Field trial of residues in pollen and nectar
o OCSPP 850.3040 (Tier 3): Field testing for pollinators
uctioin
This Preliminary Risk Assessment (PRA) examines the potential ecological risks associated with
labeled uses of paraquat on non-listed non-target organisms. Federally listed
threatened/endangered species ("listed") are not evaluated in this document. The PRA uses the
best available scientific information on the use, environmental fate and transport, and
ecological effects of paraquat. The general risk assessment methodology is described in the
Overview of the Ecological Risk Assessment Process in the Office of Pesticide Programs
("Overview Document") (USEPA, 2004). Additionally, the process is consistent with other
guidance produced by the Environmental Fate and Effects Division (EFED) as appropriate. When
necessary, risks identified through standard risk assessment methods are further refined using
available models and data. This risk assessment incorporates the available exposure and effects
data and most current modeling and methodologies.
3 Problem Formulation Update
The purpose of problem formulation is to provide the foundation for the environmental fate
and ecological risk assessment being conducted for the labeled uses of paraquat. The problem
formulation identifies the objectives for the risk assessment and provides a plan for analyzing
the data and characterizing the risk. As part of the Registration Review (RR) process, a detailed
problem formulation (USEPA, 2011a) for this PRA was published to the docket (No. 0262 EPA-
HQ-OPP-2011-0855) in December of 2011. The following sections summarize the key points of
the Problem Formulation and discusses key differences between the analysis outlined there
and the analysis conducted in this PRA.
One important update to the problem formulation is that runoff risk is not calculated here due
to the fate properties of paraquat that suggest low likelihood that bioavailable paraquat will be
present in runoff (see Section 7.1).
As summarized in the problem formulation based on previous risk assessments, potential risks
associated with the use of paraquat include risks to plants, aquatic invertebrates, mammals,
birds, terrestrial-phase amphibians and reptiles. One new use assessment was completed in
2014 (USEPA, 2014a) for paraquat dichloride use on tuberous and corm vegetables; conclusions
9
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were similar to those of prior assessments. Since the problem formulation was completed, the
following data have been submitted, which fulfill most of the data gaps:
• Ecotoxicity Data
o Acute toxicity to Eastern oysters (shell deposition study), mysid shrimp, and both
fathead and sheepshead minnows (MRIDs 49320301, 49320302, 49320303, and
49320304; all acceptable studies)
o Chronic toxicity to daphnids, mysid shrimp, and both fathead and sheepshead
minnows (MRIDs 49320305, 49320306, 49320307, and 49320308; all acceptable
studies)
o Sub-acute toxicity in whole sediment to midges, and to freshwater and estuarine
amphipods (MRIDs 49577001, 49577002, and 49577003; all acceptable studies)
o Non-guideline 21-day midge emergence sediment toxicity study and algal study with
sediment (MRIDs 48877201 and 48844202; both supplemental studies)
o Acute oral toxicity to mallard ducks and zebra finch (passerine) (MRIDs 49378001
and 49349901; both acceptable studies)
o Avian reproduction in bobwhites and mallard ducks (MRIDs 00110454 and
00110455; classified as supplemental and acceptable, respectively)
o Terrestrial plant seedling emergence and vegetative vigor (MRIDs 49320309 and
49320310; acceptable and supplemental studies, respectively)
These new data are described in more detail in the effects characterization (Section 6 and in
Appendix B). The sub-acute dietary toxicity data for the zebra finch are slightly more sensitive
than previously submitted data. The new aquatic and terrestrial studies complete the effects
data set, with the exception of additional pollinator studies, which were not requested when
the problem formulation was written.
In terms of fate data, anaerobic aquatic metabolism data and a drinking water treatability study
(i.e., Jar Test) was requested in the Problem Formulation. The drinking water treatability study
was submitted and reviewed (D396402; USEPA 2012a). However, no anaerobic aquatic
metabolism data was received.
3.1 Mode of Action for Target Pests
Paraquat dichloride is a quaternary ammonium compound widely used for broadleaf weed
control. It is a fast-acting contact herbicide used to suppress or eradicate a wide spectrum of
post-emergent weeds. It also functions as a defoliant and desiccant and is most effective on
growing plants with abundant green tissue. Paraquat is quickly absorbed by living (especially
healthy) plant tissue and produces superoxides during photosynthesis, which destroy plant
cells. It is less effective on dry, drought-stressed, woody, or fully mature plants. Because of the
quick absorption by living plant tissues, followed by rapid plant death, it is not likely to be
transported systemically throughout the plant, but locosystemically.
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3.2 Label and Use Characterization
3.2.1 Label Summary
Paraquat is an herbicide and can also be used as a defoliant/desiccant. Use sites include
terrestrial food, nonfood, feed, forestry, residential, commercial, and nursery use sites, as well
as some indoor use patterns. It is available in two formulation types: an emulsifiable
concentrate (EC) and a suspension concentrate/liquid (SC/L). The application equipment
includes aircraft, ground, low-pressure backpack or handheld sprayers, brushes or rollers, and
coils or wicks. The application method types include banded and broadcast, or spot-treatment
sprays and a tree wound treatment. It can be used pre-plant, at plant, post-emergence, prior to
harvest, post-harvest, and during dormant season.
The Biological and Economic Assessment Division (BEAD) prepared a Pesticide Label Use
Summary (PLUS) Report summarizing all registered uses of paraquat based on actively
registered labels on May 31, 2018. The PLUS report was used as the source to summarize
representative uses for this PRA. Additionally, the technical registrant responded to some
clarifying questions on labels on July 30, 2012 and responses are considered in the use
summary.
The uses considered for this Registration Review are listed in Table 3-1. Many of the current
labels do not contain sufficient information to limit maximum annual numbers of applications
or maximum annual application rates and do not specify the minimum retreatment intervals.
The highest application rates and shortest minimum application interval appropriate for the use
are used in the exposure assessment. Note that these applications rates are based on lb
paraquat cation/A. A rate of 1 lb cation/A is equivalent to 1.417 lb paraquat dichloride/A.
Table 3-1. Paraquat Use Sites and Application Characteristics
Max Single
Per Year Basis
App Rate (lb
Max lbs.
Minimum
Application
paraquat
Max#
paraquat
Retreatment
Use Site
Method
cation/acre)
Apps
cation/A
Interval
Acerola (West Indies Cherry)
G
1.01
5
NS
NS
Alfalfa
A/G
1.5
3
2
NS
Almond
G
1.01
5
NS
NS
Apple
G
1.01
5
NS
NS
Apricot
G
1.01
3
NS
NS
Artichoke
G
1.01
3
NS
7
Asparagus
A/G
1.01
3
NS
NS
Avocado
G
1.01
5
NS
NS
Banana
G
1.01
5
NS
NS
Barley
A/G
1.01
3
NS
NS
Beans, Dried-Type
A/G
0.5
2
NS
NS
Brassica (Head and Stem) Vegetables
A/G
1.01
3
NS
NS
Bushberries
G
1.01
5
NS
NS
Caneberries
G
1.01
5
NS
NS
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Max Single
Per Year Basis
App Rate (lb
Max lbs.
Minimum
Application
paraquat
Max#
paraquat
Retreatment
Use Site
Method
cation/acre)
Apps
cation/A
Interval
Carrot (Including Tops)
A/G
1.01
3
NS
NS
Cherry
G
1.01
3
NS
NS
Citrus
G
1.01
5
NS
NS
Clover
A/G
1.5
NS
NS
NS
Cocoa
G
1.01
5
NS
NS
Coffee
G
1.01
5
NS
NS
Coniferous/Evergreen/Softwood (Non-
Food)
G
1.01
5
NS
NS
Corn, Field
A/G
1.01
3
NS
NS
Corn, Pop
A/G
1.01
3
NS
NS
Corn, Sweet
A/G
1.01
3
NS
14
Cotton
A/G
1.01
4
NS
7
Cucurbit Vegetables
A/G
1.01
3
NS
NS
Deciduous/Broad leaf/Hard wood (Non-
Food)
G
1.01
5
NS
NS
Eggplant
A/G
1.01
3
NS
NS
Fallow Land
A/G
1.01
3
NS
NS
Fig
G
1.01
5
NS
NS
Flowering Plants
G
1.01
2
NS
NS
Fruiting Vegetables
A/G
1.01
3
NS
NS
Garlic
G
1.01
1
NS
NS
Ginger
G
1
6
NS
30
Grapes
A/G
1.01
5
NS
NS
Grass/Turf
A/G
1.01
3
NS
NS
Grasses Grown for Seed
A/G
1.01
3
NS
NS
Guar
G
0.5
3
NS
NS
Guava
G
0.938
4
NS
NS
Hops
G
0.5
3
NS
NS
Kiwi Fruit
G
1.01
3
NS
NS
Leafy Vegetables
A/G
1.01
3
NS
NS
Legume Vegetables
A/G
0.788
1
NS
NS
Lentils
A/G
0.5
2
NS
NS
Lettuce
A/G
1.01
3
NS
NS
Macadamia Nut (Bushnut)
G
0.475
4
NS
NS
Manioc (Cassava)
G
1.01
3
NS
NS
Melons
A/G
1.01
3
NS
NS
Mint
A/G
0.75
2
NS
NS
Nectarine
G
1.01
3
NS
NS
Okra
G
1
2
NS
NS
Olive
G
1.01
4
NS
NS
Onion
G
1.01
1
NS
NS
Papaya
G
1.01
5
NS
NS
Passion Fruit (Granadilla)
G
0.938
5
NS
NS
Pastureland/Rangeland
A/G
0.5
10
0.6
NS
Peach
G
1.01
3
NS
NS
Peanuts
G
0.938
2
NS
28
Pear
G
1.01
5
NS
NS
12
-------
Max Single
Per Year Basis
App Rate (lb
Max lbs.
Minimum
Application
paraquat
Max#
paraquat
Retreatment
Use Site
Method
cation/acre)
Apps
cation/A
Interval
Peas (Unspecified)
A/G
1.01
3
NS
NS
Peas, Dried-Type
A/G
0.5
2
NS
NS
Peas, Pigeon
G
0.5
1
NS
NS
Pepper
A/G
1.01
3
NS
NS
Persimmon
G
0.938
5
NS
NS
Pineapple
G
1.01
3
NS
NS
Pistachio
G
1.01
5
NS
NS
Plum
G
1.01
3
NS
NS
Potato, White/Irish (Or Unspecified)
A/G
0.625
3
NS
5
Premises/Areas
G
1.01
10
NS
NS
Prune
G
1.01
5
NS
NS
Rhubarb
G
1.01
2
NS
NS
Rice
A/G
1.01
3
NS
NS
Root and Tuber Vegetables
A/G
1.01
3
NS
NS
Safflower
A/G
1.01
3
NS
NS
Sage, Clary
A/G
0.75
NS
NS
NS
Sorghum
A/G
1.01
3
1.99
NS
Soybeans
A/G
1.01
3
NS
14
Strawberry
G
0.5
3
NS
NS
Subtropical/Tropical Fruit
G
0.938
4
NS
28
Sugar Beet
A/G
1.01
3
NS
NS
Sugarcane
A/G
0.938
2
NS
NS
Sunflower
A/G
1.01
3
NS
NS
Taro
G
0.788
2
NS
NS
Tobacco
G
0.938
2
NS
NS
Tomato
A/G
1.01
3
NS
NS
Tree Nuts
G
1.01
5
NS
NS
Trees (Non-Food)
G
1.01
5
NS
NS
Tuberous and Corm Vegetables
A/G
0.5
3
NS
NS
Turnip (Greens)
A/G
1.01
3
NS
NS
Tyfon
G
1.01
3
NS
NS
Vegetables (Unspecified)
G
0.75
2
NS
NS
Wheat
A/G
1.01
3
NS
NS
Yam
G
1.01
2
NS
NS
A = aerial applications; G = ground applications; NS = not specified on labels.
3.2.2 Usage Summary
Based on market usage data from 1998-2016, the agricultural usage of paraquat has increased
since approximately 2009 (Figure 1; USEPA 2018) in terms of both pounds applied and acres
treated. The screening-level use assessment (SLUA) estimate (USEPA 2016), which only
considers agricultural use, indicates that on average cotton (1,000,000 lbs), soybean (700,000
lbs), and corn (600,000 lbs) are the crops typically receiving the largest cumulative paraquat
applications per year. Other crops receiving greater than 100,000 lbs of paraquat per year on
average include alfalfa, almonds, grapes, and wheat.
13
-------
00CT>O*H(Nr0^-L/lUDr^00CT>O*H(Nr0^-L/lUD
CT1CT>0000000000*H*H*H*H*H*H*H
cncnooooooooooooooooo
*H*H(N(N(N(N(N(N(N(N(N(N(N(N(N(N(N(N(N
Years
Pounds Al (lb) ^^"Total Area Treated (acres)
Figure 1. Paraquat dichloride Total Area Treated (acres) and Al Volume (lb.) (1998-2016).
(Does not include crops surveyed only by NASS and Cal DPR)
Source: Agricultural Market Research Data (AMRD), 1998-2016
4 Residues of Concern
In this risk assessment, the stressors are those chemicals that may exert adverse effects on non-
target organisms. Collectively, the stressors of concern are known as the Residues of Concern
(ROC). The residues of concern usually include the active ingredient, or parent chemical, and
may include one or more major degradates that are observed in laboratory or field
environmental fate studies. Only one minor degradate was identified in any of the paraquat
fate studies (no major degradates). Because that degradate (QINA, 4-carboxyl-l-
methylpyridinium) was only observed in only one environmental fate study and at minor
concentrations, it was not considered a stressor of concern (see problem formulation, USEPA,
2011a). Therefore, the paraquat cation is the only residue of concern considered in this
assessment (Appendix A).
5 Environmental Fate Summary
Paraquat dichloride readily dissociates into the paraquat cation. It has a high water solubility
(700,000 mg/L) and low vapor pressure (1 x 10"9 torr). However, rather than stay in solution
after application as might be expected, paraquat readily adsorbs to soils. In fact, the primary
route of environmental dissipation of paraquat is adsorption to soil clay particles.
Paraquat does not hydrolyze, does not photodegrade in aqueous solutions, and is resistant to
microbial degradation under aerobic and anaerobic conditions. Essentially no microbial
14
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degradation of paraquat was seen after 180 days of aerobic incubation or after 60 days of
anaerobic incubation following a 30-day aerobic incubation.
Paraquat was shown to be very immobile in soil with batch equilibrium studies conducted on
four soils in the laboratory. High rates of paraquat were added because at realistic field
application rates, paraquat was below detection in the batch equilibrium adsorption solution.
There was no detectable desorption.
In laboratory studies with radiolabeled paraquat, no radioactivity volatilized from the soil
surface to adsorb to glass or to collect in volatile traps. With low vapor pressure and extremely
high adsorption coefficients, paraquat would not be expected to volatilize once applied to the
soil, but spray drift could potentially be an issue since paraquat is toxic to plants and animals.
In short and long-term field dissipation studies, paraquat residues were extractable only by acid
reflux and were shown to be persistent and to accumulate slightly with repeated applications.
Paraquat is dissipated by rapid adsorption to clay particles. Due to the apparent adsorption
strength of paraquat for soil clays, these adsorbed residues do not appear to be
environmentally available. The summaries of environmental fate studies are presented in Table
5-1.
15
-------
Table 5-1. Environmental Fate Summary of Paraquat Dichloride
Study
Value (units)1
MRID #
Study Status
Molecular Weight
257.2 g/mol
http://extoxnet. orst.edu
/pips/paraauat.htm
NA
Vapor Pressure
1 x 10"9 torr
http://extoxnet.orst.edu
/pips/paraauat.htm
NA
Solubility
700,000 mg/L
http://extoxnet.orst.edu
/pips/paraauat.htm
NA
Hydrolysis
Stable at pH 5, 7, 9
Upton et al., 1985
Acceptable
Direct Aqueous Photolysis
Stable
40562301
Acceptable
Soil Photolysis
Stable
146807
Acceptable
Aerobic Soil Metabolism
Stable
41319301
Acceptable
Anaerobic Soil Metabolism
Stable
41319302
Acceptable
Anaerobic Aquatic
Metabolism
No Study
No Study
No Study
<2 weeks (only
represents water phase.
Aerobic Aquatic Metabolism
Did not measure
amount of paraquat
sorbed to the soil)
00055093
Supplemental
68 - 50,000
Kd-ads / Kd-des (ml_/g)
(no measurable
correlation with % OC)
40762701
Acceptable
Terrestrial Field Dissipation
Half-life not calculated;
however, cited
reference indicates a
half-life of > 10 years
41293202, 42802101,
42738701, 42738702,
42802102
Acceptable
Kow (Log Kow)
<0.005 (<-2.35)
48841603
NA
BCF
No study
1AII estimated values were calculated according to "Guidance for Reporting on the Environmental Fate and
Transport of the Stressors of Concern in Problem Formulations for Registration Review, Registration Review Risk
Assessments, Listed Species Litigation Assessments, New Chemical Risk Assessments, and Other Relevant Risk
Assessments" (USEPA, 2010a).
6 Ecotoxicity Summary
Ecological effects data are used to estimate the toxicity of paraquat to surrogate species. The
ecotoxicity data for paraquat and its associated products have been reviewed previously in
ecological risk assessments, including a litigation assessment (USEPA, 2009a) and in a problem
formulation for Registration Review (USEPA, 2011a). Although only the paraquat dichloride
form is currently registered (PC code 061601), toxicity data were also considered for paraquat
(PC code 061603), and paraquat bis (methyl sulfate) (PC code 061602). All toxicity values were
converted (as needed) to the paraquat cation (molecular weight: 186.258 g/mol). The most
16
-------
sensitive and/or defensible of these data are summarized in Section 6.1 and Section 6.2.
Various studies with aquatic animals, birds, and terrestrial and aquatic plants were received
since the problem formulation was issued in 2011; the results of these studies are described
briefly in this section.
A search of the public ECOTOXicology database was conducted in June, 2018 to update
information from an ECOTOX refresh report from September, 2016. These queries (using the
three paraquat forms listed above) yielded no new data from suitable studies with more
sensitive (lower) toxicity endpoints than those previously reviewed for risk assessment.1
Although supplemental toxicity data were found that qualitatively suggested that some fish and
aquatic-phase amphibians may be more sensitive than the fish species used for risk
calculations, none of the studies provided quantitatively usable endpoints. Additional
information can be found in Appendix B, and is briefly discussed in Section 8.2.
Table 6-1 and Table 6-2 summarize the most sensitive measured toxicity endpoints available
across taxa. These endpoints are not likely to capture the most sensitive toxicity endpoint for a
particular taxon but capture the most sensitive endpoint across tested species for each taxon.
All studies in this table are classified as acceptable or supplemental. Non-definitive endpoints
are designated with a greater than or less than value. Values that are based on newly submitted
data (those submitted since the problem formulation was completed) are designated with an N
footnote associated with the MRID number in the tables.
6.1 Aquatic Toxicity
Available data indicate that paraquat TGAI (technical-grade active ingredient) is moderately
toxic to freshwater fish but less toxic to estuarine/marine fish on an acute exposure basis—due
to a non-definitive acute endpoint, paraquat may be slightly toxic to the sheepshead minnow.
The sheepshead minnow LC50 (50% lethality concentration of >41,000 |ag cation/L, MRID
49320304) was almost an order-of-magnitude less sensitive than the fathead minnow LC50
(4700 |ag cation/L, MRID 49320303). On a chronic exposure basis, the endpoints are closer, but
the freshwater endpoint is still lower; the fathead minnow NOAEC (no-observed adverse effect
concentration) is approximately half the sheepshead NOAEC (740 and 1800 |ag cation/L,
respectively; MRIDs 49320307 and 49320303). Paraquat is slightly to highly toxic to aquatic
invertebrates: moderately toxic to freshwater Crustacea, slightly toxic to estuarine/marine
mollusks, and highly toxic to estuarine/marine Crustacea (as represented by mysid shrimp) on
an acute exposure basis. Estuarine/marine Crustacea were also more sensitive than freshwater
on a chronic exposure basis; mysid shrimp (MRID 49320306) were approximately 3 times more
sensitive than freshwater daphnids (MRID 49320305).
1 There were some endpoints that were lower in the ECOTOX report; however, the endpoints were not considered
reliable for use in risk assessment.
17
-------
Sediment toxicity studies were submitted since previous risk assessments and the problem
formulation were completed. In a 10-day spiked sediment test using the freshwater amphipod
(Hyalella azteca), NOAEC/ LOAEC (lowest-observed adverse effect concentration) for reduced
survival (84% mortality at the LOAEC) were 30/61 mg cation/kg-dw (based on dry weight of
sediment). The Hyalella NOAEC is at least 6.5 times lower than that of the midge (Chironomus
riparius) and at least 3.5 times lower than that of the marine amphipod (Leptocheirus
plumulosus); see footnotes to Table 6-1, as well as Appendix B for more information on the
sediment toxicity data. However, sensitivity comparisons were not quantifiable because both
the midge and marine amphipod endpoints were based on non-definitive endpoints where no
measurable effects (to survival and growth for the midge and survival for the marine amphipod)
were found at treatment levels tested.
Differences in sensitivity might be expected because Hyalella, an amphipod, and Chironomus, a
dipteran, have different life histories, occupy different taxonomic groups (crustaceans versus
insects) and generally interact with sediments in different ways. As described in the harmonized
draft guideline (850.1735), Hyalella are epibenthic detritivores that burrow into the sediment,
while Chironomus larvae typically build a tunnel or case within the upper layers of benthic
sediments and tend to remain infaunal (submerged in the sediment). Influences of these life-
history dissimilarities on the bioavailability of paraquat are not well understood. While the
midge might be expected to proportionally consume more contaminated sediment than the
amphipod, amphipods appear to be more sensitive. One scenario might be that the movement
of the amphipod mechanically re-suspended some of the paraquat and made it bioavailable.
With such limited data, a difference in paraquat toxicity based on life history is not well
supported and the difference seen here may simply be due to species sensitivities.
The influence of pore water concentrations versus bound amounts of paraquat to sediment
toxicity could not be estimated because a comparison could not be made. The Hyalella pore
water estimates were not usable, because only the lowest and highest treatments had
detectable pore water concentrations. The midge had usable pore water measurements.
However, the Hyalella sediment NOAEC is 6.5x more sensitive than that of the midge. Using
midge data (49577001), an adjustment factor based on a simple ratio from sediment to pore
water concentration is 0.00233 (0.21 -f 90). Similarly, for the two Hyalella treatments with
measured pore water concentrations, a mean ratio of 0.0020 can be calculated (86% of the
midge ratio) using the pore water measurements (see Appendix B for more details). Because
the midge study was conducted using artificial sediment, and the Hyalella study using natural
sediment, the pore water estimate using the ratio (0.0020) from the Hyalella study seems to be
the best estimate and is used here to estimate the NOAEC and LOAEC for screening; although
the midge ratio estimate gives some support to this estimate, uncertainty is acknowledged. The
natural sediment likely caused greater adsorption of paraquat, but the influence of sediment
type is not quantified here. The midge pore water endpoint was actually the one used for risk
calculation and is presented below (NOAEC/ LOAEC = 0.21/ >0.21), while the estimated pore
water endpoint from the Hyalella data (NOAEC/ LOAEC = 0.0117/ 0.0243 |ag cation/L) is only
used to help characterize the risk.
18
-------
Although a longer-duration 21-day midge study was available (MRID 48877201), the duration
did not cover all the recommended endpoints of growth and reproduction (approximately 50-
65 days needed) but contained emergence endpoints. The study lacked pore-water
information, but based on the bulk sediment NOAEC/ LOAEC values, the midge 21-day
emergence endpoints (68/ >68 mg cation/kg-dw) were not as sensitive as the Hyalella 10-day
survival endpoints (30/ 61 mg cation/kg-dw). Therefore, no further attempt was made to
estimate either pore water concentration. Additionally, neither the 10-day nor the 21-day
midge studies provided definitive endpoints (with the 10-day NOAEC actually being higher than
the 21-day one) to use in estimating an acute-to-chronic ratio for use with the Hyalella acute
data. Due to the persistence of paraquat, this is a data gap and chronic sediment toxicity data
for Hyalella may be needed (although the utility is not clear due to the difficulties in making
comparable exposure estimates). For this assessment, the Hyalella 10-day endpoints are the
most sensitive and used in this assessment to screen for chronic risk, as well.
The freshwater diatom (Navicula pelliculosa) was approximately three orders-of-magnitude
more sensitive than the marine diatom (Skeletonema costatum), with respective EC50 and
NOAEC of 0.40 and 0.16 |ag cation/L (MRID 42601006). Data were available for eight algal
species, including 2 marine species and one cyanobacterium.
Table 6-1. Aquatic Toxicity Endpoints Selected for Risk Quotient Calculations for Paraquat
Study
Type
Test
Substance (%
a.i.)
Test Species
Toxicity Value (C.I.) in |ig
cation/L (unless
otherwise specified)
MRID or
ECOTOX No./
Classification
Comments
Freshwater Fish (surrogates for vertebrates)
Acute
TGAI: (paraquat
dichloride:
46.3%) 33.5%
cation
Fathead
Minnow
(Pimephales
promelas)
96-h LC50 = 4700 (3000 to
8500)
Slope: 4.0
N49320303
Acceptable
Moderately Toxic
Chronic
TGAI: (paraquat
dichloride:
46.3%) 33.5%
cation
Fathead
Minnow
(P. promelas)
33-day
NOAEC = 740
LOAEC = 1500
N49320307
Acceptable
Based on growth—at the
LOAEC, significant (p<0.05)
reductions of 18.7% and
13.3% in dry and wet weight,
respectively.1
Estuarine/Marine Fish (surrogates for vertebrates
Acute
TGAI: (paraquat
dichloride:
46.3%) 33.5%
cation
Sheepshead
Minnow
(•Cyprinodon
variegates)
96-h LC50 >41,000
N49320304
Acceptable
No mortality in any
treatment.2
Chronic
TGAI: (paraquat
dichloride:
46.3%) 33.5%
cation
Sheepshead
Minnow
(C. variegates)
34-day
NOAEC = 1800
LOAEC =3700
N49320308
Acceptable
Based on growth-
significant (p<0.05) 5.3% and
11.7%, respective reductions
in length and wet weigh,
also 5.1% reduction in dry
weight.3
Freshwater Invertebrates (water column)
Acute
TGAI: (92.3%
paraquat
dichloride)
66.8% cation
Water Flea
(Daphnia
magna)
48-h LC50 = 1300 (1000-1500)
Slope: 4.4
00114473
Supplemental
(quantitatively
usable)
Moderately Toxic.
The endpoint may be used
quantitatively.4
19
-------
Study
Type
Test
Substance (%
a.i.)
Test Species
Toxicity Value (C.I.) in |ig
cation/L (unless
otherwise specified)
MRIDor
ECOTOX No./
Classification
Comments
Chronic
TGAI: (46.3%
paraquat
dichloride)
33.5% cation
Water Flea
(D. magna)
3-week
NOAEC = 97
LOAEC = 200
N49320305
Acceptable
Based on growth-
significant (p<0.05) 4%
reduction in length and
biologically significant 22%
reduction in dry weight.5
Estuarine/Marine Invertebrates (water column)
Acute
TGAI: (46.3%
paraquat
dichloride)
33.5% cation
Mysid
(Americamysis
bahia)
96-h LC50 = 228 (188-277)
Slope: 4.91
N49320302
Acceptable
Highly Toxic.
Most sensitive acute aquatic
crustacean endpoint.
Acute
TGAI: (46.3%
paraquat
dichloride)
33.5% cation
Eastern Oyster
(Crassostrea
virgninica)
96-h EC/ICso = 22,500
(14,000-36,300)
Slope: N/A
N49320301
Acceptable
Slightly Toxic.
Based on shell deposition
impairment. Mollusk
endpoint two orders of
magnitude higher than
crustacean.
Chronic
TGAI: (46.3%
paraquat
dichloride)
33.5% cation
Mysid
(A bahia)
4-week
NOAEC = 38
LOAEC = 76
N49320306
Acceptable
Based on survival and
reproduction—significant
(p<0.05) resp. reductions of
38.4% and 20.5% in F0 and Fi
survival; also 49.7%
reduction in offspring/
female.6
Freshwater Invertebrates (sediment)
Sub-
Chronic
TGAI (Paraquat
dichloride):
99.4% (97.8 %
radio-chemical
purity)
Freshwater
Amphipod
(Hyalella
azteca)
10-day
Bulk sediment:
NOAEC = 30 mg cation/kg-dw
LOAEC = 61 mg cation/kg-dw
N49577003
Acceptable
Based on survival and
growth (ash-free dry
weight)—significant (p<0.05)
84% reduction in survival at
the LOAEC; the LOAEC for
weight is >30 mg cation/kg-
dw.7
Pore water estimate:
NOAEC/ LOAEC = 0.060/
0.120 mg cation/L.8
Although a 21-day midge
emergence endpoint is
available, the 10-day survival
endpoint is more sensitive
and used for chronic risk
screening.9
TGAI (Paraquat
dichloride):
99.4% (97.8 %
radio-chemical
purity)
Midge
(Chironomus
riparius)
10-day
Bulk sediment:
NOAEC / LOAEC = 90/ >90 mg
cation/kg-dw
Pour water:
NOAEC = 0.21 mg cation/L
LOAEC >0.21 mg cation/L
N49577001
Acceptable
Based on no effects (p<0.05)
to survival or growth (ash-
free dry weight).9
The midge pore water
endpoint was the only
measured pore water
endpoint available.8
Estuarine/Marine Invertebrates (sediment)
Sub-
Chronic
TGAI (Paraquat
dichloride):
99.4% (97.8 %
radio-chemical
purity)
Estuarine-
Marine
Amphipod
(Leptocheirus
plumulosus
10-day
Bulk sediment:
NOAEC = 99 mg cation/kg-dw
LOAEC = >99 mg cation/kg-
dw
N49577002
Acceptable
Based on no significant
(p<0.05) reduction in
survival.
20
-------
Study
Type
Test
Substance (%
a.i.)
Test Species
Toxicity Value (C.I.) in |ig
cation/L (unless
otherwise specified)
MRID or
ECOTOX No./
Classification
Comments
Aquatic Plants and Algae
Vascular
TGAI (Paraquat
dichloride
32.7%): 23.7%
cation
Duckweed
(Lemna gibba)
14-day EC50 = 71 (63-79)
NOAEC = 2310
LOAEC = 47
42601003
Acceptable
Based on frond number;
LOAEC based on significant
(p<0.05) 18% inhibition.
Non-
vascular
TGAI (Paraquat
dichloride
32.7%): 23.7%
cation
Freshwater
Diatom
(Navicula
pelliculosa)
4-d EC50 = 0.40
NOAEC = 0.1610
LOAEC = 0.33
42601006
Acceptable
Based on cell density; LOAEC
based on biologically
significant 54% inhibition.11
TGAI=Technical Grade Active Ingredient; a.i.= active ingredient; h = hour; C.I. = confidence interval; LC/EC/ICxx =
lethal/effects/inhibition concentration specifying percent of organisms affected; NOAEC/LOAEC = no/lowest observed adverse
effects concentration; N/A = Not available; dw = sediment dry weight; N=Studies submitted since the problem formulation was
completed are designated with an N associated with the MRID number; > Greater than values designate non-definitive
endpoints where no effects were observed at the highest level tested (USEPA, 2011b).
1 An acute-to-chronic ratio (ACR) for the fathead minnow can be calculated as 6.4 (4700/740).
2 Highest concentration tested was 41 mg cation/L mean measured concentration. No sub-lethal effects were observed.
3At the LOAEC, length and wet weight were significantly (p<0.05) decreased by 5.3 and 11.7%, and dry weight by 5.1%.
4Some uncertainty is associated with the EC50 because there were no treatment levels with no mortality (three levels total).
5 At the LOAEC, significant (p<0.05) 4% reduction in mean length and 22% reduction in mean dry weight..
6 At the LOAEC, 49% reduction in offspring/female, 51.7% red. in offspring/reproductive day, with dose-dependent pattern.
7 At the LOAEC, significant (p<0.05) 84% reduction in survival.
8 Hyalella pore water estimates were unreliable, while midge had usable pore water measurements and is used here for
screening (see discussion).
9 A midge 21-day study is available (MRID 48877201), but emergence endpoints (68/ >68 mg cation/kg-dw) were not as
sensitive as the Hyalella 10-day survival endpoints (30/ 61 mg cation/kg-dw).
10The aquatic plant NOAECs are used to calculate listed species RQs; these were not calculated in this assessment.
11 At the LOAEC, biologically significant 54% inhibition in cell density.
6.2 Terrestrial Toxicity
Available data indicate that paraquat TGAI ranges from moderately toxic to highly toxic to three
species of birds, including passerines, and is moderately toxic to mammals on an acute oral
exposure basis. Paraquat is practically non-toxic to young adult honey bees on an acute (both
contact and oral) exposure basis. Data are not available on the chronic toxicity to adult honey
bees or acute and chronic toxicity to larval honey bees.
In an 18-week reproductive toxicity study with the mallard duck (Anas platyrhynchus), the
NOAEC and LOAEC were 29.4 and 101 mg cation/kg-diet, based on reproduction and food
consumption, including significant (p<0.05) reductions of 59.0% in eggs laid, 24.7% in viable
embryos/egg set, 33.1% in live embryos/egg set, and 8.5% in mean food consumption.
The LD50 for laboratory rats was 93 mg cation/kg-bw from a dosing study (MRID 43685001), but
rats fed diets containing paraquat up to 108 mg cation/kg-diet for 138-weeks showed no
measurable effects in reproductive or offspring body weight (MRID 00126783). The endpoint
was from a 3-generation study with two mating periods, rather than a 2-generation study. No
measurable effects (p<0.05) were observed for reproduction or offspring body weight at the
highest treatment tested and, therefore, the endpoint can also be used as a 2-gen endpoint.
21
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Exposure design was 54-138 weeks for females and 43-97 weeks for males, as follows: P
females: 1st mating - 12 weeks of exposure prior to mating period, 3 weeks during gestation
period, and 3 weeks during lactation period; 2nd mating - 19-21 weeks prior to mating, 3 weeks
during gestation period, 4 weeks during lactation period; P males: 1st mating - 12 weeks prior
to mating period; 2nd mating - 19-21 weeks prior to mating; F1 females: 1st mating - 11 weeks
prior to mating, 3 weeks during gestation period, 4 weeks during lactation period; 2nd mating -
19-21 weeks prior to mating, 3 weeks during gestation period, 4 weeks during lactation period;
F1 males: 1st mating - 11 weeks prior to mating; 2nd mating - 19-21 weeks prior to mating; F2
females/males = same as Fl. An additional notation is that in the problem formulation
document (USEPA, 2011a), Table 6 has a typo showing that 108 is in units of mg cation/kg-bw,
but in Appendix A, A2. Terrestrial Organisms states that the study NOAEL was 7.5 mg cation/kg-
bw (NOAEC = 108 ppm), which was the highest test concentration. At a lower test
concentration (3.75 mg/kg-bw), an increased incidence of alveolar histiocytes was observed in
the parents; however, this value is not used for deriving chronic mammalian RQs because the
relationship of this endpoint to survival, growth or reproduction has not been established.
An additional line-of-evidence was included here because the rat chronic study showed no
reproductive or growth effects at the highest concentration tested. Although a definitive no-
effects level was found, the highest concentration tested was below the environmentally
relevant concentrations. Effects were seen in rat growth at a similar dosing range (5 mg
cation/kg-bw) in a prenatal developmental study (MRID 00113714). In that study, pregnant
females were dosed paraquat by gavage on days 6 to 15 of pregnancy and sacrificed at 21 days
to examine development of offspring. The treatment levels are not directly comparable to the
reproduction study above because of very different dosing methods and schedules (the
reproduction study was a dietary study, while in the prenatal study was a dosed study), but this
information shows that although no effects were seen at the calculated dosing of 7.5 mg
cation/kg-bw in the full reproduction study, dosing in a similar range (5 mg cation/kg-bw)
caused significant (p<0.001) maternal growth impairment (24% reduction in 3-week maternal
weight gain as compared to control) when given at the sensitive gestational stage. The
maternal NOAEL/LOAEL of 1/5 mg paraquat cation/kg/day was based on decreased body
weight gains, but also on clinical signs of toxicity (piloerection, thin and hunched appearance,
croaking). Offspring at that treatment level (5 mg cation/kg-bw) had developmental effects of
slightly decreased fetal body weights and delayed ossification. Mortality was observed
(following progressive visible deterioration in health) at the next higher treatment of 10 mg
cation/kg-bw. Clinical signs of toxicity (staining of neck and subdued nature) were noted in
these animals within 2-3 days of the first dose and evolved to more severe signs of distress
(thin, hunched, piloerection, staining around nose, forepaws and eyes) prior to death 5-7 days
after the initial exposure. Therefore, even though the multi-generational reproduction study
showed no measurable effects at 7.5 mg cation/kg-bw, another line of evidence demonstrated
that growth and survival effects can occur at 5-10 mg cation/kg-bw.
The available data for terrestrial plants exposed to formulated products containing between
19.2 and 22.4% cation indicate that paraquat exposure to seeds in treated soils resulted in
reduced plant (cocklebur) emergence by 20.5% at application rates equivalent to 0.341 lb
22
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cation/A and exposure to foliage resulted in reduced plant (soybean) height by 19.8% (followed
by dose-dependent increases of 39.0% and 46.2% at the next two higher treatment levels) at
application rates equivalent to 0.018 lb cation/A (MRIDs 42639601 and 49320309);
corresponding NOAELs were 0.171 and 0.0048 lb cation/A. These data suggest that paraquat
exposure through direct spray, as in the vegetative vigor study, is more potent to plants than
application to soil or runoff, as in the seedling emergence study.
Table 6-2. Terrestrial Toxicity Endpoints Selected for Risk Estimation for Paraquat
Study Type
Test Substance
(%a.i.)
Test Species
Toxicity Value
MRIDor
ECOTOX No./
Classification
Comments
Birds (surrogates for terrestrial amphibians and reptiles)
Acute Oral
TGAI: (96.1%
paraquat
dichloride)
72.4% cation
Zebra Finch
Poephila
guttata
14-day (single-dose)
LD5o = 26.5 mg
cation/kg-bw
N49349901
Acceptable
Highly Toxic.
Sub-Acute
Dietary
TEP: (29.1%
paraquat
dichloride)
21.1% cation
Japanese
Quail
Coturnix
coturnix
5-day LC50 = 698
(593-821) mg
cation/kg-diet
Slope: 6.06 (±1.31 sd)
00022923
Acceptable
Moderately Toxic.
Chronic
TGAI: (43.5%
paraquat
dichloride)
31.5% cation
Mallard Duck
Anas
platyrhynchus
18weeks
NOAEC = 29.4
LOAEC = 101 mg
cation/kg-diet
00110455
Acceptable
Based on reproduction and
food consumption-
significant (p<0.05) reductions
of 59.0 % in eggs laid, 24.7%
in viable embryos/egg set,
33.1% in live embryos/egg set,
and 8.5% in mean food
consumption.
Mammals
Acute Oral
TGAI: 33%
cation
Rat
Rattus
norvegicus
LD5o = 93 mg
cation/kg-bw1
43685001
Acceptable
Moderately Toxic.
Based on female mortality 1
Chronic (3-
Generation
Reproduction)2
TGAI
Rat
R. norvegicus
138 weeks2
NOAEL = 7.5
LOAEL >7.5 mg
cation/kg-bw/day
(NOAEC = 108 ppm-
diet)
00126783,
00149748,
00149749
Acceptable
Based on no measurable
effects in reproductive or
offspring body weight.2
Teratogenicity/
Prenatal
Developmental
TGAI: 38%
cation
Rat
R. norvegicus
3 weeks (dosed on
days 6-15 of
pregnancy)
Maternal
NOAEL/LOAEL = 1/5
mg paraquat
cation/kg/day
00113714
Acceptable
Additional line of evidence
used due to uncertainties with
the multi-generation study.
Maternal NOAEL/LOAEL = 1/5
mg paraquat cation/kg/day
based on decreased body
weight gains.
Terrestrial Invertebrates
Acute Contact
(adult)
TEP: EC
Formulation
with 25.2%
cation
Honey bee
Apis mellifera
L.
LD50 = 52 |ig
cation/bee
43942603
Acceptable
Practically Nontoxic.
23
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Study Type
Test Substance
(%a.i.)
Test Species
Toxicity Value
MRID or
ECOTOX No./
Comments
Classification
TEP: EC
Acute Oral
Formulation
Honey bee
LD50 = 22 |ig
43942603
Practically Nontoxic.
(adult)
with 25.2%
cation
A. mellifera L.
cation/bee
Acceptable
Chronic Oral
TEP
Honey bee
No Data
(adult)
A. mellifera L.
Acute Oral
(larval)
TEP
Honey bee
A. mellifera L.
No Data
Chronic Oral
(larval)
TEP
Honey bee
A. mellifera L.
No Data
Terrestrial and Wetland Plants
Monocots (Oat,
Avena sativa):
TEP:
14-day IC25 = 0.635 lb
Seedling
Oat Study:
Formulation
with 22.4%
cation
Various
cation/acre;
NOAEL/LOAEL =
0.28/0.57 lb
cation/acre
N49320310
Supplemental
(quantitative!
y usable)
Monocot: NOAEL based on
significant (p<0.05) 21.1%
inhibition in both survival and
emergence.3
Emergence
Cocklebur
species
Dicots (Cocklebur,
Dicot: NOAEL based on
biologically significant 20.5%
reduction in emergence.4
Study:
Formulation
with approx.
Xanthium
strumarium)'.
21-day IC25 = 0.67 lb
42639601
Acceptable
19.2% cation
cation/acre; NOAEL/
LOAEL = 0.171/0.341
lb cation/acre
Monocots (Perennial
Ryegrass, Lolium
perenne):
21-day IC25 = 0.02 08
Vegetative
TEP:
Formulation
Various
(0.016-0.0253) lb
cation/acre; NOAEL/
LOAEL= 0.018/0.033
lb cation/acre
N49320309
Monocot: NOAEL based on
significant (p<0.05) 59.5% dry
weight inhibition.5
Vigor
with 22.4%
cation
species
Dicots (Soybean,
Glycine max):
21-day IC25 = 0.02 17
(0.0106-0.0406) lb
cation/acre; NOAEL/
LOAEL = 0.0048/
0.018 lb cation/acre
Acceptable
Dicot: NOAEL based on
significant (p<0.05) 19.8%
height inhibition.6
TGAI=Technical Grade Active Ingredient; a.i.= active ingredient; h = hour; C.I. = confidence interval; LC/EC/ICxx =
lethal/effects/inhibition concentration specifying percent of organisms affected; NOAEC/LOAEC = no/lowest observed adverse
effects concentration; N/A = Not available; dw = sediment dry weight; N=Studies submitted since the problem formulation was
completed are designated with an N associated with the MRID number; > Greater than values designate non-definitive
endpoints where no effects were observed at the highest level tested (USEPA, 2011b).
1 Endpoint is for females and was reported as 283 mg paraquat dichloride technical concentrate/kg-bw (converted to cation
using a 0.33 cation purity factor). Male LD50= 113 mg cation/kg-bw (344 mg paraquat dichloride technical concentrate/kg-bw).
2 The rat reproduction endpoint used is from a 3-generation study. No effects (p<0.05) were measured for reproduction or
offspring body weight at the highest treatment tested. An additional notation is that in the problem formulation document
(USEPA, 2011a), Table 6 has a typo showing that 108 is in units of mg cation/kg-bw, but in Appendix A, A2. Terrestrial
24
-------
Organisms states that the study NOAEL was 7.5 mg cation/kg-bw (NOAEC = 108 ppm), which was the highest test
concentration.
3 Monocot (oat): LOAEL was based on significant (p<0.05) inhibition in oat survival and emergence; all endpoints were based on
measured concentrations. The 0.14 and 0.28 lb cation/A treatments also had a 15.8% reduction, which were not considered
treatment related, although some uncertainty is acknowledged.
4 Dicot (cocklebur): LOAEL was based on a biologically significant (although not statistically significant at p<0.05) 20.5%
reduction in emergence at the LOAEL, along with demonstration of a dose-related general decrease in emergence.
5 Monocot (ryegrass): LOAEL was based on significant (p<0.05) 59.5% inhibition at the LOAEL of 0.033 lb cation/A, followed by a
dose-dependent 95.4% inhibition at 0.11 lb cation/A.
6 Dicot (soybean): LOAEL was based on significant (p<0.05) 19.8% inhibition of height at 0.018 lb cation/A, followed by dose-
dependent pattern of inhibition of 39.0% and 46.2% at the next two higher treatment levels.
6.3 Incident Data
The Incident Data System (IDS) provides information on the available ecological pesticide
incidents reported since registration and up to June 14, 2018, the date of the most recent
search. This database was searched for ecological incidents involving paraquat dichloride (PC
code 061601), paraquat (PC code 061603), and paraquat bis (methyl sulfate) (PC code 061602).
Although paraquat and paraquat bis (methyl sulfate) are no longer registered for use in the
United States, like paraquat dichloride, the active ingredient of both of these chemicals is
paraquat. Therefore, it was assumed that incidents associated with paraquat and paraquat bis
(methyl sulfate) would be representative of incidents that may occur when paraquat dichloride
is applied.
Table 6-3 provides a listing of the available incident reports found (also see Appendix E). These
include:
• 7 incidents involving dogs and birds (4 were actually outside of the U.S. and not included
as domestic incidents, but are provided for characterization purposes),
• 4 fish kills,
• 1 bee kill, and
• 27 plant damage incidents.
Some information is also available as aggregated counts of wildlife, plant, and other non-target
species incidents; the totals are presented in
Table 6-4, also see Appendix E); these totals show:
• 4 vertebrate wildlife incidents,
• 3 non-vertebrate (other non-target) incidents, and
• 78 plant incidents.
Many of these incidents were previously described in the problem formulation document
(USEPA, 2011a) and Appendix H of the litigation (Red-Legged Frog) assessment (USEPA, 2009a).
Incident updates are briefly discussed below. Pertinent information is also discussed in the risk
assessment sections that follow.
25
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Table 6-3. Paraquat Incidents from the Incident Data System (IDS) with Certainty Index of Possible or Greater Likelihood
Incident
Number
Year
State
Product and Additional
Active Ingredients
Legality
Certainty
Index
Use Site
Species
Distance
Magnitude/Other Notes
Birds and Mammals
1007334-001
1998
IL
Gramoxone (paraquat)
Also involved: Canopy
(metribuzin and chlorimuron
ethyl) and Dual (s-
metolachlor)
Undetermined
Possible
N/R
Corn
Vicinity
4 bird deaths
I008168-0011
1998
VA
Gramoxone Extra (paraquat)
Also involved: (Simazine),
Extrazine II 4L (Atrazine and
Simazine), Asana XL
(Esfenvalerate)
Registered Use
Probable
Corn
Canada
Goose
10 feet from
creek
5
I020627-0332
2001
WA
Not specified3
Undetermined
Probable
Agricultural
area
Dog
Distance not
given but
paraquat
possibly used
in two
locations
2 killed, others sickened
I021685-0022
2009
Not U.S.:
Ireland4
Paraquat in carcass/meat3
Undetermined
Probable
Bait,
carcass/meat
Eagle/
Golden
Eagle
N/R
1 each
I021848-0032
2010
Not U.S.:
Ireland4
Paraquat and carbofuran
laced into pieces of meat
and animal carcasses3
Undetermined
Possible
Bait,
carcass/meat
Eagle
N/R
13
I021848-0042
2007
2010
Not U.S.:
Ireland4
Paraquat and carbofuran
laced into pieces of meat
and animal carcasses3
Undetermined
Possible
Unknown
Red Kites
N/R
1-4 killed
I027242-0012
2014
Not US:
Cayman
Islands4
Not specified3
Undetermined
Possible
Veterinarian
determined
ingestion of
paraquat
Dog
Vicinity
1
Fish
B0000502-18
1981
VA
Not specified
Undetermined
Possible
Agricultural
Area
Sunfish
Adjacent
1 largemouth bass, and 53
sunfish
1009314-005
1997
IN
Gramoxone Extra
Registered Use
Possible
Treated field
Bluegill/
Crappie/
250 feet
Unreported number in a
1-acre pond.
26
-------
Bass
The 250-feet distance was
reported to be covered by
heavy sod which showed
no signs of herbicide
damage.
1005805-0001
1997
IN
Possibly Gramoxone
Undetermined
Possible
Treated field
Bluegill/
Crappie/
Bass
250 feet
Unreported number in a
1-acre pond.
The 250-feet distance was
reported to be covered by
heavy sod which showed
no signs of herbicide
damage.
1008768-007
1999
N/R
Gramoxone
Undetermined
Possible
Treated field
Bluegill/
Crappie/
Bass
N/R
200 bass and bluegills in a
% acre pond; at least 2
frogs; no mortality to
pond catfish
Pollinators
1029512-
000042
2016
N/R
Gramoxone SL 2.0
Undetermined
Possible
Unknown
Honey
Bee
Adjacent
2 hives
Plants
1007334-001
1998
IL
Gramoxone (paraquat)
Also involved: Canopy
(metribuzin and chlorimuron
ethyl) and Dual (s-
metolachlor)
Undetermined
Possible
N/R
Corn
Vicinity
18 of 103 acres
1007371-008
1997
PA
Gramoxone (paraquat)
Also involved: Bladex 90 DF
(Cyanazine)
Misuse
(accidental)
Highly
Probable
Soybean
Soybean
Vicinity
Not given
1007371-033
1997
PA
Gramoxone (paraquat)
Also involved: Bladex 90 DF
(Cyanazine)
Misuse
(accidental)
Probable
Corn
Grass
Vicinity
Not given
1007371-034
1997
PA
Gramoxone (paraquat)
Also involved: Bladex 90 DF
(Cyanazine)
Misuse
(accidental)
Probable
Corn
Grass
Vicinity
Not given
1009573-009
1999
AL
Gramoxone (paraquat)
Also possibly involved:
Exceed (prosulfuron and
primisulfuron-methul)
Undetermined
Possible
N/R
Corn
Treated
directly
75% of 200 Acres
1011838-038
2001
GA
Gramoxone (paraquat)
Also involved: Valor
(flumioxazin) and Prowl
Undetermined
Possible
Peanut
Peanut
Treated
directly
All 25 Acres
27
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(pendimethalin)
1011838-055
2001
NC
Gramoxone (paraquat)
Also involved: Dual (s-
metolachlor) and Frontier
(dimethenamid)
Registered Use
Possible
N/R
Peanut
N/R
10 acres
1011838-091
2001
OK
Cyclone (paraquat)
Also involved: Valor
(flumioxazin) and Prowl
(pendimethalin)
Undetermined
Possible
Peanut
Peanut
N/R directly,
but from write-
up appears to
be on site.
80 acres
1012366-023
2000
VA
Gramoxone (paraquat)
Also involved: Python
(flumetsulam), Bicep
(atrazine and s-metolachlor)
and Princep (simazine)
Undetermined
Possible
Corn, field
Corn,
Field
N/R directly,
but from write-
up appears to
be on site.
120 acres
1012684-010
2001
VA
Gramoxone (paraquat)
Also involved: Valor
(flumioxazin) and Dual (s-
metolachlor)
Registered Use
Possible
Peanut
Peanut
N/R directly,
but from write-
up appears to
be on site.
5 acres
1013554-040
2002
IL
Gramoxone Max
Misuse
Probable
N/R
Corn,
Field
On site
1040 acres
1013636-029
1996
OR
Gramoxone (paraquat)
Also involved: "other
unknown ingredients" in a
tank mix
Registered Use
Possible
N/R
Pepperm
int
Treated
directly
181 acres
1013884-014
1998
WA
Not specified3
Undetermined
Possible
Potato?
Apple
Vicinity
Not given
I013884-0382
1998
WA
Not specified3
Registered Use
Probable
Pea
Orname
ntal
Vicinity
Not given
Over-spray was noted.
State inspector observed
"paraquat symptoms"
1014034-009
2003
GA
Gramoxone MAX
Registered Use
Possible
Pasture
Pasture
Grass
Treated
directly
60 acres
I014409-0012
1992
WA
Not specified3
Undetermined
Possible
N/R
Radish
Vicinity
Not given
Unlicensed application.
1014409-024
1992
WA
Not specified3
Misuse
Possible
Wheat
Alfalfa
Vicinity
Not given
1016940-005
2005
CA
Gramoxone
Misuse
(intentional)
Probable
Wheat
Wheat
Adjacent
120 of 184 acres
I020459-0252
2000
WA
Not specified3
Undetermined
Probable
Corn, sweet
Winter
Wheat
Adjacent
2.5 acres
I020627-0192
2001
WA
Not specified3
Undetermined
Probable
Agricultural
area
Blueberr
y
Adjacent
Not given
28
-------
I020627-0362
2001
WA
Not specified3
Undetermined
Probable
Agricultural
area
Alfalfa
Drift from field
(distance not
given)
Not given
I020998-0232
2002
WA
Unspecified paraquat
product3
Also involved: unspecified
carfentrazone-ethyl product
Misuse
Possible
Hops
Cherry
Drift from field
(distance not
given)
Number not given
I021276-0062
2004
WA
Not specified3
Undetermined
Probable
Agricultural
area - onion
Corn
Vicinity
Not given
Unspecified paraquat
Orname
ntal
I021457-0152
2006
WA
product3
Also involved: unspecified
glyphosate product
Undetermined
Possible
N/R
Adjacent
Many
I023444-0122
2011
PA
Gramoxone Inteon3
Undetermined
Possible
Corn, field
Corn
On site
100% of 130 acres
1023587-006
2011
CA
Gramoxone Inteon
Undetermined
Possible
Cotton
Vegetabl
e
Vicinity
100% of 25 acres
1028934-
00016
2016
CA
GRAMOXONE SL 2.0
Undetermined
Possible
Agricultural
area
Onion
Vicinity
145 acres
N/R = not found in report.
1An incident from 1989 (1000097-015) involving sparrows, grackles and robins was not included in this table because the certainty was "Unlikely." A summary is
included in Appendix H of the Red-Legged Frog assessment (USEPA, 2009a).
2 Incident was new or not previously summarized. Summary of information about this incident can be found in Appendix E.
3 Incident was listed under PC. Code: 61603 (paraquat cation); all other incidents cited in this table were listed under PC Code: 61601 (paraquat dichloride). Although a search
was made for PC Code: 61602 (paraquat bis [methyl sulfate]), no incidents were found associated with that code.
4 Four incidents are listed here for discussion, even though they occurred outside of the U.S. (in Ireland and the Cayman Islands; 1021685-002,1021848-003,1021848-004, and
1027242-001).
Table 6-4. Paraquat Aggregate Incidents from the Incident Data System (IDS) for PC Codes 061601 and 061603
Taxa
Number of Incidents1
Vertebrate Wildlife (W-B)
4 (061601)
Plant (P-B)
78 (061601)
Non-vertebrate (ONT)
3 (061601) + 1 (061603) = 4
W-B = wildlife incidents; P-B = plant incidents; ONT = other non-target species incidents.
1 Aggregate incidents are only reported as a count based measure.
29
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The problem formulation document (USEPA, 2011a) contained an August 2011 review of the
Ecological Incident Information System (EMS, version 2.1), the Aggregate Incident Reports (v.
1.0) database, and the Avian Incident Monitoring System (AIMS). These incidents occurred
between 1981 and 2005 and included a total of 4 incidents involving paraquat, 26 incidents
involving paraquat dichloride, and no incidents involving paraquat bis (methyl sulfate). That
analysis of incident reports identified a concern for acute aquatic exposures because of
incidents where paraquat was a suggested cause offish mortality; a discussion of those
incidents is found in the problem formulation and also here in Section 8.2.1.
The recently updated incident summaries (also see Appendix E) only contained one incident
that was from a registered use and was of probable likelihood, an incident involving plant
damage.
Some of the incidents that were of undermined legality involved mortality of dogs (1020627-033
and 1027242-001; 1027242-001 occurred outside of the U.S.) and several birds (1021685-002,
1021848-003, and 1021848-004, all occurred outside of the U.S.); these cannot be attributed to
registered use, but do support a line of evidence that paraquat can be toxic to terrestrial
vertebrates. One bird incident involving Canada geese (1008168-001) was from a registered use
on corn and of probable causality, but also involved other pesticides; however, in this case,
even though atrazine, simazine, cyanazine and esfenvalerate were also involved, paraquat was
considered to be the pesticide present in the tank mix at an amount representing the highest
acute toxicity to birds. A noteworthy incident involving mortalities of several passerines (robins,
sparrows, starlings and grackles) was previously described in the problem formulation (USEPA,
2011a); the report indicated that it was certain that carbofuran was responsible for the
mortalities and probable that paraquat was responsible (1005750-001,1004169-026 and
1000097-015).
One incident (1029512-0004) involved damage to two bee hives and was of possible causality
but of undetermined legality. Additionally, many of the ONT (other non-target) aggregate
incidents in
Table 6-4 are likely bee incidents and are assumed to be from registered uses unless additional
information is provided to show otherwise.
These incidents suggest potential for harm to non-target aquatic and terrestrial animals, but
whether this potential extends to registered uses is not clearly substantiated. The potential for
damage to non-target plants is supported by at least five incidents associated with paraquat
registered use.
Damage to a range of taxa were found in the incident report; absence of reported incidents for
other taxa not represented should not be interpreted as an absence of incidents. Incident
reports for non-target organisms typically provide information only on mortality events and
plant damage. Sublethal effects in organisms such as abnormal behavior, reduced growth
and/or impaired reproduction are rarely reported, except for phytotoxic effects in terrestrial
plants. In addition, there have been changes in state monitoring efforts due to a lack of
30
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resources. However, the incident data that are available suggest that exposure pathways for
paraquat are complete for aquatic organisms, and possibly for terrestrial vertebrates and
invertebrates and plants, and that exposure levels are sufficient to result in field-observable
effects.
7 Ana lysis Plan
7.1 Overall Process
This assessment uses a weight of evidence approach that relies heavily, but not exclusively, on a
risk quotient (RQ) method. RQs are calculated by dividing an estimated environmental
concentration (EEC) by a toxicity endpoint (i.e., EEC/toxicity endpoint). This is a way to
determine if an estimated concentration is expected to be above or below the concentration
associated with the effects endpoint. The RQs are compared to regulatory levels of concern
(LOCs). The LOCs for non-listed species are meant to be protective of non-target organisms. For
acute and chronic risks to vertebrates, the LOCs are 0.5 and 1.0, respectively, and for plants, the
LOC is 1.0. The acute and chronic risk LOCs for bees are 0.4 and 1.0, respectively. In addition to
RQs, other available data (e.g., incident data) can be used to help understand the potential risks
associated with the use of the pesticide.
Exposure estimates for aquatic and terrestrial organisms were assessed by grouping some use
patterns, listed on currently registered labels, that have similar application rates. The registered
labels generally contained amount limits on a per crop-cycle basis, that could be used to
estimate the annual maximum. Many of the uses registered did not specify the re-application
interval. Labels restricting the interval ranged from 5-days to 30-days; where no interval was
defined, it was conservatively assumed to be 7-days for modeling based on BEAD (Biological
and Economic Analysis Division) recommendations.
For aquatic risk calculations, due to the rapid and strong adsorption to soil/sediment, exposure
to bioavailable paraquat through runoff and/or erosion is unlikely within the modeled pond
(i.e., the paraquat in runoff and erosion would enter the pond, but not in a bioavailable state
and would be unlikely to subsequently detach from the sediment particles and become
bioavailable to organisms in the overlying water). However, there is a relatively high certainty
of aquatic exposure through spray drift to the same waterbody since spray drift will largely
occur under good weather conditions when waters are largely free of any recently introduced
suspended sediment. Therefore, only spray drift exposures were modeled.
Since the paraquat introduced into a waterbody through drift, runoff, and erosion would
subsequently adsorb rapidly to suspended solids and bottom sediments, chronic exposures in
littoral (lemnic zone) and pore waters (benthic zone) are considered unlikely and were not
modeled. There is less certainty regarding potential exposure to sediment-ingesting organisms
(chiefly epibenthic and infaunal detritivores) since it is unknown to what degree the gut of a
detritivore is capable of remobilizing any paraquat attached to sediment particles. However,
31
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this route of exposure was modeled by estimating sediment concentrations assuming no
sediment burial as well as with sediment burial implemented in the Agency's standard aquatic
model.
For terrestrial EEC calculations, only direct application and spray drift were assessed. Runoff
was not assessed, consistent with the aquatic exposure assumptions, and also supported by the
mode of action (suggesting paraquat will not be present systemically in plants, see Section 3.1),
and by plant toxicity data (suggesting that direct spray is a more potent route of exposure than
runoff exposure, see Table 6-2). For spray drift exposure, the highest and lowest single
application rates were assessed. For birds and mammals, multiple applications were also
assessed for the highest and mid-range application rates. Most uses tended to have the same
or similar application rates of 0.5 or 1.01 lb cation/A, while two uses (alfalfa and clover) had a
higher rate of 1.5 lb cation/A and a few had slightly different variations of the rates and were
grouped with others with similar rates (e.g., peanuts with a 0.938 lb cation/A rate was grouped
with others with a 1.01 lb cation/A rate).
7.1.1 Listed Species
In November 2013, the EPA, along with the Services and the United States Department of
Agriculture (USDA), released a summary of their joint Interim Approaches for assessing risks to
endangered and threatened (listed) species from pesticides. The Interim Approaches were
developed jointly by the agencies in response to the National Academy of Sciences' (NAS)
recommendations and reflect a common approach to risk assessment shared by the agencies as
a way of addressing scientific differences between the EPA and the Services. The NAS report2
outlines recommendations on specific scientific and technical issues related to the
development of pesticide risk assessments that EPA and the Services must conduct in
connection with their obligations under the ESA and FIFRA.
EPA received considerable public input on the Interim Approaches through stakeholder
workshops and from the Pesticide Program Dialogue Committee (PPDC) and State-FIFRA Issues
Research and Evaluation Group (SFIREG) meetings. As part of a phased, iterative process for
developing the Interim Approaches, the agencies will also consider public comments on the
Interim Approaches in connection with the development of upcoming Registration Review
decisions. The details of the joint Interim Approaches are contained in the white paper Interim
Approaches for National-Level Pesticide Endangered Species Act (ESA) Assessments Based on
the Recommendations of the National Academy of Sciences April 2013 Report,2 dated
November 1, 2013.
2 Available at http://www2,epa.gov/endangered-species/assessing-pesticides-under-endangered species-
acttfreport
32
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Given that the agencies are continuing to develop and work toward implementation of the
Interim Approaches to assess the potential risks of pesticides to listed species and their
designated critical habitat, this ecological risk assessment for paraquat does not contain a
complete ESA analysis that includes effects determinations for specific listed species or
designated critical habitat. Although EPA has not yet completed effects determinations for
specific species or habitats, this assessment assumed, for all taxa of non-target wildlife and
plants, that listed species and designated critical habitats may be present in the vicinity of the
application of paraquat. This assessment will allow EPA to focus its future evaluations on the
types of species where the potential for effects exists once the scientific methods being
developed by the agencies have been fully vetted. Once the agencies have fully developed and
implemented the scientific methodology for evaluating risks for listed species and their
designated critical habitats, these methods will be applied to subsequent analyses for paraquat
as part of completing this registration review.
7.1.2 Endocrine Disrupter Screening Program (EDSP)
As required by FIFRA and the Federal Food, Drug, and Cosmetic Act (FFDCA), EPA reviews
numerous studies to assess potential adverse outcomes from exposure to chemicals.
Collectively, these studies include acute, subchronic and chronic toxicity, including assessments
of carcinogenicity, neurotoxicity, developmental, reproductive, and general or systemic toxicity.
These studies include endpoints which may be susceptible to endocrine influence, including
effects on endocrine target organ histopathology, organ weights, estrus cyclicity, sexual
maturation, fertility, pregnancy rates, reproductive loss, and sex ratios in offspring. For
ecological hazard assessments, EPA evaluates acute tests and chronic studies that assess
growth, developmental and reproductive effects in different taxonomic groups. As part of the
Preliminary Ecological Risk Assessment for Registration Review, EPA reviewed these data and
selected the most sensitive endpoints for relevant risk assessment scenarios from the existing
hazard database. However, as required by FFDCA section 408(p), paraquat is subject to the
endocrine screening part of the Endocrine Disruptor Screening Program (EDSP).
EPA has developed the EDSP to determine whether certain substances (including pesticide
active and other ingredients) may have an effect in humans or wildlife similar to an effect
produced by a "naturally occurring estrogen, or other such endocrine effects as the
Administrator may designate." The EDSP employs a two-tiered approach to making the
statutorily required determinations. Tier 1 consists of a battery of 11 screening assays to
identify the potential of a chemical substance to interact with the estrogen, androgen, or
thyroid (E, A, or T) hormonal systems. Chemicals that go through Tier 1 screening and are found
to have the potential to interact with E, A, or T hormonal systems will proceed to the next stage
of the EDSP where EPA will determine which, if any, of the Tier 2 tests are necessary based on
the available data. Tier 2 testing is designed to identify any adverse endocrine-related effects
caused by the substance, and establish a dose-response relationship between the dose and the
E, A, orT effect.
33
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Under FFDCA section 408(p), the Agency must screen all pesticide chemicals. Between October
2009 and February 2010, EPA issued test orders/data call-ins for the first group of 67 chemicals,
which contains 58 pesticide active ingredients and 9 inert ingredients. A second list of chemicals
identified for EDSP screening was published on June 14, 20133 and includes some pesticides
scheduled for registration review and chemicals found in water. Neither of these lists should be
construed as a list of known or likely endocrine disruptors. Paraquat is not on List 1 or List 2. For
further information on the status of the EDSP, the policies and procedures, the lists of
chemicals, future lists, the test guidelines and Tier 1 screening battery, please visit our website.4
7.2 Modeling
Various models are used to calculate aquatic and terrestrial EECs (see Table 7-1). The specific
models used in this assessment are discussed further below. The PWC (v. 1.52) was only used to
estimate sediment concentrations. Surface water exposure through spray drift alone was
calculated using a spreadsheet to avoid the runoff and erosion contributions that PWC would
have included. (Paraquat in runoff and erosion is considered to be strongly adsorbed and not
bioavailable for limnetic exposures.)
3 See httpi//www,regulations,gov/ttidocuroentPetail;D=EPA-HQ-OPPT-2009-0477-0074 for the final second list of
chemicals.
4 Available: httpi//www,epa.gov/endo/
34
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Table 7-1. List of the Models Used to Assess Risk
Environment
Taxa of Concern
Exposu re
Media
Exposure Pathway
Model(s) or Pathway
Aquatic
Vertebrates/
Invertebrates
(including sediment
dwelling)
Surface water and
sediment
Runoff and spray drift
to water and
sediment
PRZM-VVWM with PWC
version 1.21
Aquatic Plants
(vascular and
nonvascular)
Terrestrial
Vertebrate
Dietary items
Ingestion of residues
in/on dietary items as
a result of direct foliar
application
T-REX version 1.5.22
Plants
Spray drift
Spray drift to plants
TERRPLANT version 1.2.2
Bees and other
terrestrial
invertebrates
Contact
dietary items
Spray contact and
ingestion of residues
in/on dietary items as
a result of direct
application
BeeREX version 1.0
All
Environments
All
Movement through
air to aquatic and
terrestrial media
Spray drift
AgDRIFT version 2.1.1
(Spray drift)
1 The Pesticide in Water Calculator (PWC) is a Graphic User Interface (GUI) that estimates pesticide concentration
in water using the Pesticide Root Zone Model (PRZM) and the Variable Volume Water Model (VVWM).
PRZM-VVWM.
2 The Terrestrial Residue Exposure (T-REX) Model is used to estimate pesticide concentration on avian and
mammalian food items.
3 The Kow based Aquatic Bioaccumulation Model (KABAM) is used to estimate exposure to terrestrial animals that
may consume aquatic organisms when a chemical has the potential to bioconcentrate or bioaccumulate. The
general triggers for running this model is that: the pesticide is a non-ionic, organic chemical; the Log Kow value is
between 3 and 8; and the pesticide has the potential to reach aquatic habitats.
8 Aquatic Organisms Risk Assessment
8.1 Aquatic Exposure Assessment
8.1.1 Modeling
There are two major uncertainties with paraquat exposure estimates. First, paraquat does not
follow the typical soil/sediment adsorption/desorption relationships modeled by the Agency's
aquatic exposure models. Upon exposure to water or soil moisture, paraquat dichloride loses
the negatively charged chloride ions to become a positively charged cation. In the presence of
soil or sediment, the available adsorption data indicates that the paraquat cation preferentially
35
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adsorbs to clay to such an extent that levels of paraquat are undetectable in the water phase of
the adsorption studies even at high doses. Only at experimental doses many times those
expected from the maximum single paraquat application rate and in soils/sediments comprised
of little clay do the clay adsorption sites reach saturation with any excess paraquat cations (i.e.,
paraquat accumulated beyond that needed to reach adsorption site saturation) accumulating in
the water phase.
This behavior is demonstrated in a batch equilibrium study (MRID 40762701) in which paraquat
adsorption/desorption was studied in four soil types under both normal and greatly
exaggerated application rates. To measure adsorption, 200 ml of 0.01 M CaCh solution plus
standard reference paraquat was added to the samples at 1, 10, 800 and 1000 mg/kg soil in the
loam soil, at 1, 10, 300, and 500 mg/kg soil in the silty clay loam soil, at 1,10, 100 and 150
mg/kg soil in the loamy sand soil, and at 1, 10, 20 and 40 mg/kg soil in the sand soil. The 1
mg/kg soil concentration is approximately equal to 1.8 lbs ai/A, which is higher than the highest
current single application rate (1.5 lbs ai/A). Therefore, the 10x to 1000x application rate
multipliers in Table 8-1 are 10 to 1000 times the 1.8 lbs ai/A and therefore, represent the
accumulation of hundreds of years of paraquat applications at some of the highest
experimental application rates. According to the study, the two much higher application rates
for each soil were devised (based on preliminary experiments) to be above the "strong
adsorption capacity of the soil", which varies with each soil tested. The term "strong adsorption
capacity of the soil" is used to refer to the highest concentration of paraquat in soil at which
there is no detectable paraquat in the equilibrium solution of the soil slurry.
Table 8-1. Paraquat Batch Equilibrium Study (MRID 40762701) Summary
Application Rate
Mutiplier
(unitless)
Aqueous Phase
Concentration (ng ai/ml)
Soil Phase Cocentration
(Ugai/g)
Kd (ml/g)
Loam Soil (Cation Exchange Capacity = 12.9 meq/lOOg; Sand = 62%; Silt = 17%; Clay = 21%)
lx
<0.0075
>0.85
>110
10x
<0.0075
>9.9
>1300
800x
0.016
799.7
50,000
1000x
0.624
999.5
42,000
Silty Clay Loam Soil (Cation Exchange Capacity = 15.2 meq/lOOg; Sand = 14%; Silt = 57%; Clay = 29%)
lx
<0.0075
>8.5
>110
10x
<0.0075
>98.5
>1300
300x
0.032
299.4
9400
500x
0.093
498.2
5400
Loamy Sand Soil (Cation Exchange Capacity = 6.6 meq/lOOg; Sand = 81%; Silt = 11%; Clay = 8%)
lx
<0.0075
>8.5
>110
10x
<0.0075
>98.5
>1300
100x
<0.0075
>985
>13,000
150x
0.0255
1495
5900
Sand Soil (Cation Exchange Capacity = 1.9 meq/lOOg; Sand = 94%; Silt = 4%; Clay = 2%)
lx
<0.0075
>8.5
>110
10x
0.02
9.6
480
20x
0.09
18.2
200
40x
0.455
30.9
68
36
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In the first soil of this table (loam), the lx and 10x application rate trials do not produce
measurable concentrations of paraquat in the equilibrium solution of the soil slurry and
therefore, produce Kds that are only known to be larger than Kd value listed for that trial
(denoted as However, at the exaggerated rates of 800x and lOOOx, paraquat can be
measured in the soil slurry at equilibrium, which produces Kds that are 50,000 and 42,000,
respectively. Similar results are produced for the other soils, but with declining high application
rate multipliers (because the "strong adsorption capacity of the soil" is decreasing as the cation
exchange capacity [CEC] and clay content decline) as well as declining Kd estimates for these
soils because the equilibrium slurry concentrations (in the denominator of the Kd equation) are
increasing.
For the last soil with CEC of 1.9 meq/lOOg and clay content of 2%, the 10x and "high"
application rate multipliers of 20x and 40x all produce relatively lower Kd estimates compared
to the other soils tested. The pattern presented in Table 8-1 appears to be that Kds are high at
low application rate multipliers, but continuously decrease as the application rate multiplier
increases relative to the "strong adsorption capacity of the soil".
Amondham et al 2006 assessed paraquat adsorption in eight tropical soils of Yom River Basin,
Thailand and fit Freundlich isotherm models to each of the soils studied. These fits provided 1/n
values ranging from 0.19 to 0.41. More typical values range from 0.9 to 1.0 with 1.0 indicating
the equilibrium distribution between soil and water phases of the batch equilibrium studies are
not dependent on concentration (i.e., the concentrations in both water and soil increase
proportionally as the amount applied varies). Therefore, the low values observed indicate that
the equilibrium distribution varies strongly with the amount of paraquat applied with almost all
of the paraquat being absorbed to the soil phase at low levels of application and appreciable
water phase concentrations appearing only when large amounts have been applied (Figure
8-1). These isotherm plots show accumulations of paraquat in the soil of 1000 mg/kg
(equivalent to 1000 applications at 1.8 lbs ai/A) before the concentration in water begins to
appreciably increase for seven of the soils. However, similar to the results of MRID 40762701,
the sand soil (soil #6 in Figure 8-lb) appears to have its adsorption capacity exceeded after little
soil accumulation (i.e., potentially at low numbers of applications).
37
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8000
_ 6000
ho
DO
- 4000
6
O Soil#2
0 Soil#l
~— SoB#3
+ Sofl#4
o Soil#7
8000
(b)
_ 6000
bO
J*
DO
r-
A—
= 4000
A
-------
In a registrant-submitted aerobic soil metabolism study (MRID 41319301), paraquat applied at
a rate equivalent to 0.9 lbs ai/A was shown to: 1) adsorb to a sandy loam soil (CEC 10.8
meq/100 g; sand 64%; silt 22%; clay 14%); and 2) not metabolize in that adsorbed state for 180
days. The soil samples were extracted three times with the extracted compounds identified
separately for each extract. In the first extraction, the soil samples were shaken with 100-150
ml of methanol for 1 hour. (In MRID 46098802, paraquat's solubility limit was 1000 mg/L in
methanol, but less than 11 mg/L in n-hexene, toluene, dichloromethane, acetone, and ethyl
acetate.) Despite paraquat's affinity for methanol, <0.2% of the applied paraquat (Table 8-2)
was released from any of the incubated soil samples even at 180 days indicating again that the
paraquat is tightly adsorbed to soils with adequate CEC and clay content.
Table 8-2. Distribution of Radioactivity in Soil Treated with 14c-pyridyl Labelled Paraquat
Portion-
Analysed
Radioactivity Recovered as % of Applied (Paraquat as % of Applied)
0
3
7
30
61
90
180
1st Extract
<0.2
<0.2
<0.2
<0.2
<0.2
<0.2
<0.2
2nd Extract
95.3 (92.3)
98.6 (93.0)
81.7 (79.8)
83.3 (82.1)
83.6 (81.4)
80.0(77.3)
73.5 (72.9)
3rd Extract
7.4 (7.2)
3.3
10.5 (9.9)
10.4 (10.2)
12.2 (11.7)
12.0(11.5)
21.7 (20.5)
14co2
NA
<0.1
<0.1
<0.1
<0.1
<0.1
<0.1
Unextracted
4.1
1.9
4.1
1.2
1.4
0.5
0.7
Total Extracted
106.8
103.8
96.3
94.9
97.2
92.5
95.9
Total Paraquat
Extracted
99.5
96.3
89.7
92.3
93.1
88.8
93.4
The second extract was for 2-4 hours with 100 or 150 ml of aqueous technical grade (not
radiolabeled) paraquat solution (7440 ppm paraquat cation) in order to desorb radiolabeled
[14C]paraquat by isotopic exchange. The clear majority of the radiolabeled paraquat was
released from the soil by being exchanged with the non-labeled paraquat. To identify the
remaining unextracted residues, the soil was further extracted by a 5-6 hour reflux with 6 M HCI
(3rd extract), which resulted in the total paraquat extracted being greater than 88% of the
applied in every sampling interval. (Note that <0.1% of the applied radioactivity was
metabolized to C02, and the unextracted residues following the 3rd extract were consistently
less than 5% of the applied radioactivity, ensuring that little if any degradates could have been
produced, but adsorbed and characterized as unextracted residues.) This experiment indicates
the paraquat did not metabolize during the experiment when it was tightly adsorbed to soil,
with the study authors estimating a half-life in excess of 10 years but provides no indication of
the rate of degradation that would occur in any bioavailable (not in an absorbed state)
paraquat.
In the open literature studies, the previously described Amondham et al study (2006) that
assessed paraquat adsorption, degradation, and remobilization in eight tropical soils of Yom
River Basin, Thailand, did measure paraquat degradation. In the field portion of this study, first
order dissipation rates of 36 days (low application rate) and 46 days (high rate), whereas a half-
life Of 166 days was calculated for the laboratory study. The difference in rates between field
and laboratory was attributed to differences in temperature (field being warmer) and soil
39
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photolysis. In Ricketts (1999), isolates of soil bacterial were shown to be capable of degrading
paraquat with rapid production of CO2 (approximately 50% of applied radioactivity) with no
paraquat remaining in the study at 30 days (half-life could not be calculated). The CADPR (no
date) has a more comprehensive review of the scientific literature regarding paraquat
environmental fate.
The degradation found in these open literature studies is likely due to the higher application
rates of paraquat relative to the amount of soil occurring in the open literature studies with
faster rates likely occurring in those experiments where a larger proportion of the paraquat was
bioavailable (i.e., in a disolved phase) with:
• No degradation at the typical application rates in the Agency guideline study;
• Faster degradation under the higher application rates (greater bioavailability) in
Amondham et al (2006); and
• Fastest degradation rates achieved in Ricketts (1999) since the bacteria and paraquat
occurred in a soil free (no adsorption) environment.
Therefore, the persistence of paraquat appears to be an artifact of the Agency guideline study
design, rather than an actual property of the paraquat molecule. Considering these degradation
findings in conjunction with the previously discussed adsorption findings, it appears likely that
paraquat only accumulates (persists) in the environment when it is in a non-bioavailable state
and degrades rapidly when bioavailable. Because of these unique properties of paraquat, the
typical aquatic exposure assessment was modified as described in the following sections.
Acute Water Column Exposure Calculations
For acute aquatic environmental exposures, it would be more likely that the highest
concentrations in the water column would occur immediately after spray drift enters the pond.
Since spray drift would likely occur under good weather conditions when water column
suspended sediment concentrations would often be low (i.e., not during or immediately after a
run-off producing storm event), the paraquat entering the pond could remain in solution and
impact aquatic organisms. Therefore, paraquat exposure was modeled as spray drift only
concentrations which vary with application method (aerial vs. ground) and application rate. This
assumes that the spray drift enters the waterbody, causes a brief high concentration, and then
quickly dissipates via adsorption to clay in sediment.
Note that this acute exposure is calculated outside of the standard Agency aquatic exposure
model (PWC) since PWC would include 50% of the paraquat entering the pond through runoff
and erosion as partitioning into the overlying pond water. Therefore, the acute exposure to
paraquat (Peak) is calculated as:
SprayFrac(unitless) x AppRate(Kg/ha) x PondSA(ha) x CF([ig/Kg)
Peak^'L^ = PondVolume(L)
40
-------
Where:
SprayFrac is the fraction (0.125 for aerial and 0.062 for ground) of the application rate that
falls on the USEPA standard pond;
AppRate is the single application rate to the crop-specific scenario modeled;
PondSA is the surface area of the USEPA standard pond (1 ha);
CF is a conversion factor to convert from kilograms to micrograms (1 x 109 ng/Kg); and
PondVolume is the volume of the USEPA standard pond (2 x 107 L).
Current EFED guidance (USEPA 2017) is to calculate an average 24-hour exposure as the acute
exposure. However, there is no dissipation rate available for paraquat from which this average
24-hour exposure can be calculated. Therefore, the instantaneous peak values calculated in
Table 8-3 may over-estimate exposure to aquatic organisms to some unknown extent. This
method is equivalent to how PWC calculates spray drift contribution to EECs assuming no
degradation occurs on the day of the drift event (also see Appendix C).
Table 8-3. Acute Aquatic Exposures to Paraquat Dichloride through Drift Based on Application
Type and Application Rate
Application Rate
Application Type (Spray
Drift Fraction)
Acute(peak)Exposure
(ug cation/L)
(lbs cation/A)
(kg cation/Ha)
0.5
0.56
Aerial (0.125)
3.5
Ground (0.062)
1.7
1.01
1.13
Aerial (0.125)
7.1
Ground (0.062)
3.5
1.5
1.68
Aerial (0.125)
10.5
Ground (0.062)
5.2
Sediment Exposure Estimates
Based on the assumption that paraquat quickly and strongly adsorbs to sediment (suspended or
deposited at the bottom of waterbodies), there would be no meaningful chronic exposure via
overlying water or pore water. However, some organisms ingest sediment, and it is unknown if
the digestive systems of these organisms would be able to desorb some fraction of the
paraquat from the ingested sediment. Therefore, conservative sediment exposure estimates
were modeled: 1) using the Agency's aquatic exposure model (PWC); 2) assuming the vast
majority of the paraquat entering the standard pond accumulated in the sediment; and
3) assuming all of the paraquat in this sediment was available to these benthic organisms. The
PWC modeling parameters appear in Table 8-4.
Table 8-4. PRZM-EXAMS Input Parameters
Input Parameter
Value
Reference/Comment
Molecular Weight
257.2 g/mol
http://extoxnet.orst.edu/oips/oaraauat.htm
Vapor Pressure
1 x 10"9 torr
htto://extoxnet. orst.edu/oios/oaraauat. htm
Solubility
700,000 mg/L
htto://extoxnet. orst.edu/oios/oaraauat. htm
41
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Input Parameter
Value
Reference/Comment
Kd
Uncertain (1000 ml/g
based on analysis
presented below)
MRID 40762701
Incorporation Depth
0 cm
Foliar Application
Application Rate
1.01 (lb ai/ac)
1.13 (kg ai/ac)
Maximum Application Rate for FIFRA Section 3
Registrations
Number of Applications
4 (MS Cotton)
10 (FLTurf)
Maximum Number Allowed
First Application Date
April 26 (MS Cotton)
January 26 (FLTurf)
Minimum Interval = 28 days
Application Efficiency
0.95 (MS Cotton)
0.99 (FLTurf)
Aerial Spray
Ground Spray
Spray Drift Fraction
0.125 (MS Cotton)
0.062 (FLTurf)
Aerial Spray
Ground Spray
Hydrolysis
Stable (pH 5,7, 9)
Upton et al., 1985
Aqueous Photolysis Half-life
Stable
MRID 40762701
Water Half-life
Stable
MRID 00055093
Benthic Half-life
Stable
MRID 41319302
Soil Half-life
Stable
MRID 41319301
The two scenarios presented in Table 8-5 were chosen to provide a range of potential sediment
exposure values. Because the value of the soikwater partition coefficient (Kd is assumed since
adsorption under paraquat saturation conditions was related to clay content) is uncertain, a
range of Kd values was explored to identify a value that would yield conservative sediment
EECs. In Figure 8-2a, the Mississippi Cotton scenario (typically considered to be a scenario that
yields high-end exposure estimates) indicates that the highest total fraction of pesticide applied
to the field transported to the pond based on modeled exposure from drift, runoff, and erosion
occurs at or near a Kd of 1000. Figure 8-2b investigates the Florida turf scenario (typically
considered to be a scenario that yields much more moderate exposure estimates due to
erosion being attenuated by a two-centimeter-thick thatch layer) which produced much lower
total pesticide fraction transported. (Note the y-axis scale change and that attempts to model
Kd values higher than 10,000 produced a PWC error.) Based on these results and the Kd
constraints imposed by the model, a Kd of 1000 was chosen as a Kd value that should result in
high-end (conservative) sediment EECs (i.e., this Kd value likely provides a conservative value
because it is high enough to minimize leaching in the field and produce greater erosive
transport, while still allowing some runoff to the pond).
42
-------
Florida Turf
Mississippi Cotton
.08
•Total
•Total
.07
Runoff
Runoff
tj 2 0.015
.06
Erosion
Erosion
q3 0.05
Drift
Drift
£ 0.04
ro 0.03
.02
Q. £
0
1.E-
.E+04
b
Soil: Water Partion Coefficient (kd)
Soil:Water Partion Coefficient (kd)
Figure 8-2. Comparison of the Relationship Between Total Pesticide Transport and SoikWater
Partition Coefficient in a Typically High-End Exposure Scenario (a) and More Moderate
Exposure Scenario (b)
Based on the Kd selected (1000 ml/g), the PWC bulk sediment EECs are graphically depicted in
Figure 8-3 based on two different modeling options. The blue lines depict the standard
estimates assuming no sediment burial, while the red lines depict the same estimates with the
sediment burial routine implemented. In the MS cotton scenario, the paraquat accumulates
continuously over time without sediment burial, but quickly reaches a much lower steady state
concentration when sediment burial is implemented. If we think of the red and blue lines as
high and low estimates bracketing some true accumulation trend over time, then this true
accumulation trend has a high level of uncertainty for this scenario. In the MS cotton scenario,
high amounts of erosion carrying adsorbed paraquat either cause the concentration to build
continuously or level off quickly to a low sediment concentration due to continuous burial by
the latest eroded soil entering the waterbody. Conversely for the FL turf scenario, the with and
without sediment burial bulk sediment EECs plot directly on top of each other, which indicates
very little erosion is occurring in this scenario and therefore, no sediment burial.
No Sediment Burial
No Sediment Burial
Mississippi Cotton (assuming Kd = 1000)
60 140
*3) 120
E,
. 100
1/1/61 1/1/65 1/1/69 1/1/73 1/1/77 1/1/81 1/1/85 1/1/89 1/1/93
Date
Florida Turf (assuming Kd = 1000)
"53 140
"So 120
£
. 100
o
c
O 80
20
0
1/1/61 1/1/65 1/1/69 1/1/73 1/1/77 1/1/81 1/1/85 1/1/89 1/1/93
Date
Figure 8-3. Comparison of Sediment Estimated Environmental Concentrations for Two
Scenarios with and without Sediment Burial Implemented based on a 1.0 lbs ai/A Application
Rate
43
-------
The EECs estimated from these scenarios are listed in Table 8-5. Three of the scenarios (MS
cotton without sediment burial and both with and without for FL turf) have continuously
accumulating EECs, which are described by their 30-year concentration (i.e., the accumulated
concentration that occurs at the end of 30 years). Only one scenario (MS cotton with sediment
burial) reaches a steady state EECs, which is described with a l-in-10-year concentration.
Table 8-5. Estimated Concentrations in Sediment after Thirty Years based on a 1.0 lbs ai/A
Application Rate1
Scenario
Application
Type
Sediment Burial
Water Concentration EEC
(|ig cation/L)
Sediment Concentration EEC
(mg cation/Kg)
MS Cotton
Aerial
Without
150
150
With
7.18
7.18
FLTurf
Ground
Without
46.3
46.3
With
46.3
46.3
1 Pore water and sediment EECs represent the accumulated concentration that occurs at the end of 30 years.
8.1.2 Monitoring
The Water Quality Portal (https://www.waterqualitydata.us/) was searched for paraquat
monitoring data. The water samples (from NWIS, STEWARDS, STORET) comprise 1381 results
from 64 sites. Among the 1381 water samples, there are only 14 detections by two
organizations: California State Water Resources Control Board (CASWRCB) and South Florida
Water Management District (SFWMD). Of the 1277 SWFMD samples, only 1 sample had
paraquat detected at 1.4 |-ig/L. However, there is no indication of what type of water sample
was collected (total, dissolved fraction, etc.) for any of the SWFMD samples. The other
paraquat detections are all from CASWRCB with 13 detections (ranging from 0.24 to 3.6 |-ig/L)
out of 68 water samples collected by this organization. These samples are total water samples
indicating that the samples were not filtered and therefore, the paraquat detected may be
attached to suspended sediment rather than dissolved in water (i.e., total samples are less
indicative that the paraquat detected is bioavailable). The remaining 36 samples had non-
detectable levels of paraquat and are from the Chumash Mission Indian tribe (7 samples),
National Park Service (1), Pomo Indian tribe (27), and Utah Department of Environmental
Quality (1). The U.S. Geological Survey (USGS) which typically provides the majority of samples
for pesticides from Water Quality Portal data set, does not monitor for paraquat.
A different compilation of California data
(https://www.cdpr.ca.gov/docs/emon/surfwtr/surfdata.htm) from the California Department
of Pesticide Regulation (CDPR) contains many of the same samples, but does include five
samples that were not incorporated into the Water Quality Portal data set, while also excluding
five samples that were in the Water Quality Portal data set. Out of 2099 samples in the CDPR
data set, 13 detections were included ranging from 0.1 to 3.6 |-ig/L. It is difficult to reconcile the
two data sets because: 1) many of the 'Agency' names in the CDPR data set appear to fall under
the umbrella of the CASWRCB organization name included in the Water Quality Portal data set;
2) many of the non-detects recorded in the CDPR data set are omitted from the Water Quality
44
-------
Portal data set; and 3) the CDPR data set does not record the water sample type (total,
dissolved fraction, etc). The CDPR data summarized by collecting Agency (Table 8-6).
Table 8-6. Summary of the Paraquat Data Contained California Department of Pesticide Regulation
(CDPR) data set
Collecting Agency
Number of
samples
Number
Detected
Highest
Detected
(Hg/L)
Buena Vista Coalition*
12
0
NA
E. San Joaquin Water Quality Coalition (RWB5lrrigated Lands
Monitoring)*
419
3
1.5
Kaweah River Sub-Watershed*
45
0
NA
Kern River Sub-Watershed*
71
0
NA
Kings River Sub-Watershed*
35
2
1.1
Michael L Johnson, LLC
445
2
0.68
Pacific Ecorisk
164
1
0.67
S. San Joaquin Water Quality Coalition (RWB5 Irrigated Lands
Monitoring)*
94
1
0.01
Sacramento Valley Water Quality Coalition (RWB5 Irrigated Lands
Monitoring)*
171
0
NA
San Joaquin County and Delta Water Quality Coalition (RWB5 Irrigated
Lands Monitoring)*
330
1
3.6
Tetra Tech, Inc.
60
0
NA
Tule River Sub-Watershed*
47
0
NA
University of California-Aquatic Ecosystems Analysis Laboratory
38
0
NA
Westside San Joaquin Water Quality Coalition (RWB5 Irrigated Lands
Monitoring)*
168
3
1.4
* Appear to be subdivisions of the California State Water Resources Control Board (CASWRCB).
These studies were not specifically targeted at paraquat use areas and the frequency of sample
collection in all studies was not adequate to ensure the capture of peak concentrations.
Monitoring data are useful in that they provide some information on the occurrence of
paraquat in the environment under existing usage conditions. However, the measured
concentrations should not be interpreted as reflecting the upper end of potential exposures
unless they were collected in areas with frequent sampling and where usage was occurring.
Absence of detections from non-targeted monitoring cannot be used as a line of evidence to
indicate exposure is not likely to occur because it is often collected in areas where the pesticide
is not used. Additionally, modeling results are not expected to be similar to monitoring results
as monitoring does not reflect the conceptual model and the sampling frequency and duration
often does not reflect what is simulated in modeling (i.e., daily concentrations). However,
monitoring data is a useful line of evidence to explore whether exposure in the environment is
occurring at the levels of the modeled EECs and whether monitoring shows that exposure is
occurring at levels that are higher than toxicity endpoints. For non-targeted monitoring data, if
exceedances are not occurring this is not evidence that exceedances will not occur with usage;
however, if there are exceedances, it confirms that exposure occurred in the environment at
levels where effects are expected to occur.
45
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8.2 Aquatic Organism Risk Characterization
8.2.1 Aquatic Vertebrates
Risk estimates showed no acute LOC exceedances for aquatic vertebrates from water column
exposure (Table 8-7). Chronic RQs could not be calculated due to previously described fate
characteristics. However, when chronic toxicity endpoints (based on growth, see Table 6-1)
were conservatively screened against the acute EECs, the exposure:toxicity ratios were all less
than or equal to 0.01, indicating that that estimated exposure concentrations are less than
those expected to produce chronic effects.
Table 8-7. Acute and Chronic Vertebrate Risk Quotients for Non-listed Species
Risk Quotient
Peak EEC,
Hg cation/L1
Freshwater
Estuarine/Marine
Use Pattern
Acute
Chronic
Acute
Chronic
LCso = 4700
NOAEC = 740
LCso = >41,000
NOAEC = 1800
|ig cation/L
|ig cation/L
|ig cation/L
|ig cation/L
Almond and Clover,
1.5 lb cation/A
- Aerial
10.5
<0.01
Chronic RQs
could not be
calculated;
however if the
<0.01
- Ground
5.2
<0.01
<0.01
Chronic RQs could
not be calculated;
however if the
chronic endpoint is
screened against
the acute EECs, the
ratio is <0.01 for
all use patterns.
Multiple Uses -
Highest Rate, 1.10 lb
cation/A
- Aerial
7.1
<0.01
chronic
endpoint is
screened
against the
<0.01
- Ground
3.5
<0.01
acute EECs,
<0.01
Multiple Uses - Lower
Rate, 0.5 lb cation/A
3.5
<0.01
the ratio is
0.01 or less for
<0.01
- Aerial
all use
- Ground
1.7
<0.01
patterns.
<0.01
A lack of Bolded values shows that no RQs exceed the LOC for acute risk to non-listed species of 0.5 or the chronic
risk LOC of 1.0. The endpoints listed in the table are the endpoint used to calculate the RQ.
1 The EECs used to calculate these RQs are based on the l-in-10-year peak value from Table 8-3; for this
assessment, this value is also used to screen for chronic risk; see explanation in Section 8.1.1.
As described in Section 8.1.1, paraquat is not expected to remain long in the water column.
This is consistent with risk estimates.
However, information from the open literature suggests that some species of fish and aquatic-
phase amphibians may be as much as an order-of-magnitude more sensitive than the
quantitatively usable fish endpoints used here; Appendix B cites studies conducted with Red-
eyed Treefrogs (Agalychnis callidryas, Ghose, etal., 2014, E168034) and Gourami Fish
(Trichogaster trichopterus, Banaee, etal., 2013, E172383; references in Appendix B) although
due to insufficient information in both cases, the study results were not quantitatively useable
to calculate risk. These LC50 endpoints were approximated between 1,240 and 1,410 |ag
46
-------
cation/L, based on the assumption that the reported concentrations are based on paraquat
dichloride and are converted to cation (this is unconfirmed for the frog endpoint). If these
endpoints are used to estimate risk, they would not change the risk conclusions; for example, if
the highest peak EEC (10.5 |ag cation/L) is divided by 1240 |ag cation/L, the ratio is <0.01, which
is below the 0.5 level of concern for non-listed species.
Additionally, six incidents involved aquatic organisms, with paraquat dichloride suspected of
being the primary cause in 4, and of these 1 was from a registered use (1009314-005; fish-kill
involving bluegill, crappie, and bass) and 3 of undetermined legality (B0000502-18, 1005805-
0001, and 1008468-007; fish-kills involving sunfish, bluegill, crappie, and bass). The incident
known to be from a registered use (1009314-005) is the strongest evidence of potential damage
to non-target aquatic life. No other pesticides were implicated. The fish kill occurred in a one-
acre pond in Madison, IN, approximately 250 feet from the edge of a treated field. The incident
was determined to be of unknown cause but of suspected pond turnover. One potential
scenario suggests that the pond may have suffered low dissolved oxygen from paraquat
damage to aquatic plants, but the report also states that the distance between the treated field
and pond was entirely covered by heavy sod which showed no signs of herbicide damage, so
the sod plants may have been less sensitive than the aquatic plants involved. The causality is
not entirely clear, but does seem to be associated with paraquat registered use.
Similar scenarios were described in two additional incidents, with the exception that legality
was undetermined. Incident 1005805-001 (Jefferson, IN), also involved a one-acre pond
approximately 250 feet from a treated field; no other pesticides were implicated. Bluegill, bass,
and crappie were killed and the report suggests that pond turnover was suspected. The
distance between treated field and pond was also covered by sod that showed no sign of
herbicide damage. In Incident B0000-502-18 (Frederick Co., VA), the report stated that runoff of
paraquat from adjacent fields was involved in killing one largemouth bass and 53 sunfish, the
theory being that it killed the vegetation in the pond and caused a low D.O. (2.0 ppm at 1200
hours). Also, the reporter stated that the organisms in the stream feeding the pond were
destroyed by toxic concentrations of paraquat. Causality was determined to be of possible
certainty. No other pesticides were implicated. These incidents are somewhat consistent with
three incidents involving direct application of diquat dibromide to waterbodies that likely
caused deaths of aquatic animals due to low dissolved oxygen following a large die-off of
aquatic plants (see diquat assessment, USEPA, 2015). However, the incident involving runoff
(B0000-502-18) challenges the assumption used in this assessment that runoff will be minimal
due to very strong binding to clay. One possible explanation is that the exposure pathway cited
in the incident report may have been incorrect, and the actual exposure involved spray drift.
This would be consistent with several of the other incidents where the pond was approximately
250 feet from treated fields, and the sod between each field and pond showed no signs of
herbicide damage, suggesting that although the sod plants, as well as the aquatic plants, were
exposed to spray drift, they may have been less sensitive, perhaps by having a sound root
structure that was not exposed to the drift.
47
-------
Another fish-kill incident (1008768-007) involved approximately 200 dead bluegill and bass
combined, and at least two frogs, but no deaths to pond catfish in a three-quarter acre pond.
This incident was reported by a Conservation Officer and was determined to be of
undetermined legality and "possible" certainty; however, this incident involved application of
multiple pesticides (also including chlorimuron-ethyl and metribuzin).
These incidents suggest potential for harm to aquatic organisms from paraquat exposure, and
one of these incidents was linked to a registered use. The pathway of damage is possibly from
oxygen sinks due to plant aquatic die-offs. The available acute toxicity data do not suggest that
fish will die from direct exposure; however, estimated environmental concentrations are at or
above the effects concentrations for algae and so the scenario of algal die-offs resulting in
aquatic animal mortality is supported. The exposure pathway is not entirely clear, due to one
incident being attributed to runoff, but fate characteristics suggest that spray drift is a much
more likely pathway.
A low number of reported incidents should not be construed as the absence of incidents.
Incident reports for non-target animals typically provide information only on mortality events.
Sublethal effects in organisms such as abnormal behavior, reduced growth and/or impaired
reproduction are rarely reported.
Based on the available data, the risk to fish and aquatic-phase amphibians from the use of
paraquat cannot be precluded due to fish-kill incidents and the persistence of adsorbed-phase
paraquat.
8.2.2 Aquatic Invertebrates
Risk estimates showed no acute LOC exceedances for aquatic invertebrates from water column
exposure (Table 8-8). Chronic RQs could not be calculated due to previously-described fate
characteristics. However, when chronic toxicity endpoints (based on growth, reproduction and
survival see Table 6-1) were conservatively screened against the acute EECs, the
exposure:toxicity ratios were all less than one, indicating that that estimated exposure
concentrations are less than those expected to produce chronic effects.
48
-------
Table 8-8. Acute and Chronic Aquatic Invertebrate Risk Quotients
Risk Quotient
Freshwater
Estuarine/Marine
Use Pattern
Peak EEC,
Hg cation/L1
Acute
Chronic
Acute
(Crustaceans)
Acute
(Mollusks)
Chronic
LCso = 1300
NOAEC = 97
LCso = 228 |ig
LCso = 22,500
NOAEC = 38
|ig cation/L
|ig cation/L
cation/L
|ig cation/L
|ig cation/L
Almond and Clover,
1.5 lb cation/A
10.5
<0.01
Chronic RQs
0.046
<0.01
Chronic RQs
- Aerial
could not be
could not be
- Ground
5.2
<0.01
calculated;
however if
the chronic
0.023
<0.01
calculated;
however if
the chronic
Multiple Uses -
Highest Rate, 1.10 lb
cation/A
- Aerial
7.1
<0.01
endpoint is
0.031
<0.01
endpoint is
screened
against the
acute EECs,
the ratio is
<1 (0.04-
screened
against the
acute EECs,
the ratio is
<1 (0.09-
- Ground
3.5
<0.01
0.015
<0.01
Multiple Uses -
Lower Rate, 0.5 lb
cation/A
- Aerial
3.5
<0.01
0.015
<0.01
0.11) for all
use patterns.
0.28) for all
use patterns.
- Ground
1.7
<0.01
<0.01
<0.01
A lack of Bolded values shows that no RQs exceed the LOC for acute risk to non-listed species of 0.5 or the chronic
risk LOC of 1.0. The endpoints listed in the table are the endpoint used to calculate the RQ.
1 The EECs used to calculate these RQs are based on the peak values from Table 8-3; for this assessment, these
values are also used to screen for chronic risk; see explanation in Section 8.1.1.
As described in Section 8.1.1, paraquat's strong tendency to adsorb to components of sediment
does not fit some of the assumptions usually made for aquatic exposure estimates,
necessitating adjustments to the usual calculation of 24-hour and 21-day EECs. Because
paraquat is assumed here to increase steadily over time, the acute and 21-day EECs are similar
and are represented together as a 21-day estimate; the longer-term estimate is a 30-year
estimate (Table 8-9) based on 1.01 lb cation/A applications (note that for uses with 1.5 lb
cation/A, the exposure and risk estimates would be 50% higher). Due to the non-standard
timeframes, actual RQs were not calculated for sediment, but screenings were conducted by
calculating the ratios of exposure estimates with sediment toxicity endpoints.
49
-------
Table 8-9. Aquatic Benthic Invertebrate Risk Quotients for Non-listed Species based on a 1.0
lbs ai/A Application Rate
Use Site
EEC
EEC:Toxicity Ratios Based on Sub-Chronic Toxicity (10-
Day Study-Exposure to Dosed Sediment)
Bulk Sediment, |ig
cation/kg-DW1
Pore
Water
Estimate,
Hg
cation/L2
Freshwater
Estuarine
/Marine
Crustacean
(Hyalella)
Insect (Chironomus)
Crustacean
(Leptocheirus)
21-day
30-year
30-year
NOAEC =
30,000 |ig
cation/kg-
DW3
NOAEC =
90,000
|ig cation
/kg-DW3
Pore W.
NOAEC
= 210
Hg
cation/
L4
NOAEC =
99,000 |ig
cation/kg-DW3
21-
day
30-
year
MS Cotton Aerial
- Without Burial
<10,000
150,000
150
<0.5
5.0
1.7
0.71
1.5
-With Burial
<10,000
7,180
7.18
<0.5
0.2
0.08
0.03
0.07
FLTurf Ground
- Without Burial
<10,000
46,300
46.3
<0.5
1.5
0.51
0.22
0.47
-With Burial
<10,000
46,300
46.3
<0.5
1.5
0.51
0.22
0.47
Bolded values show ratios where risk cannot be precluded because the ratios exceed the LOC for acute risk to non-
listed species of 0.5 or the chronic risk LOC of 1.0. The endpoints listed in the table are the endpoint used to
calculate the ratio.
1 The bulk sediment EECs are based on chemical-specific assumptions described in Section 8.1.1. The acute (short-
term) EEC is based on visual inspection of Figure 8-2 which shows that the sediment concentration does not reach
10 mg/kg during the first two years. The 30-year estimate is from Table 8-5.
2 The sediment pore water EEC estimates are based on chemical-specific assumptions described in Section 8.1.1
and presented in Table 8-5.
3 Measured bulk sediment concentration.
4 Measured pore-water concentration.
Although the pore water risk estimate using the midge data (Table 8-9) does not show LOC
exceedances, screening using the lower Hyalella NOAEC pore water estimate of 60 |ag cation/L
does estimate risk concerns above the LOC for all scenarios except MS Cotton With Burial (see
footnote to Table 6-1 and notes for MRID 49577003 in Appendix B). The Hyalalla pore water
screening estimate is in agreement with the Hyalella bulk sediment risk estimate. Pore water
estimates are difficult to interpret due to paraquat's strong adsoption (Sections 5 and 7.1).
Calculated risk to benthic organisms is heavily influenced by the length of time available for
accumulation to occur, as well as the scenario used for modeling exposure. As described in
Section 8.1.1, many uncertainties are acknowledged. Despite the uncertainties, using
conservative assumptions showed that risk to benthic organisms was low from short-term
sediment exposure (including a 21-day time-frame, usually used to designate chronic
exposure). However, when paraquat is allowed to accumulate in the sediment overtime (30-
year exposure estimate), risk to benthic organisms may be a concern based on a 1.01 lb
cation/A application rate and would be approximately 50% greater if based on 1.5 lb cation/A.
50
-------
Although freshwater Crustacea were more sensitive than freshwater insects or saltwater
Crustacea, all categories had LOC exceedances when based on the most conservative EEC
estimate (MS Cotton without burial assumed).
Information from the open literature suggests that some crustacean species may be more
sensitive than the invertebrate endpoints used here; Appendix B cites a study conducted with
another daphnid (Diaphanosoma excisum, Leboulanger, et. a!., 2009, E112408; reference in
Appendix B); however, due to insufficient information, the study results were not
quantitatively useable to calculate risk. This endpoint was approximated at an LC50 of 40 |ag
cation/L if the reported concentration is assumed to be based on paraquat dichloride and is
converted to cation (this is unconfirmed). This endpoint is a rough estimate of the LC50 based on
40-60% mortality at that treatment level, rather than a calculated value. If this endpoint were
used to estimate risk, it would not change the risk conclusions; for example, if the highest peak
EEC (10.5 |ag cation/L) is divided by 40 |ag cation/L, the ratio is 0.26, which is below the 0.5 level
of concern for non-listed species.
Based on the available data, the risk to aquatic invertebrates from the use of paraquat is
expected to be low from water column exposure, but potentially of concern over time from
sediment exposure due to paraquat's persistence when adsorbed to sediment. The potential
for epibenthic and infaunal detritivores that ingest sediment to be exposed to toxic amounts of
paraquat would depend largely on their ability to desorb paraquat from ingested sediment in
the gut. This potential is not quantifiable. However, long-term paraquat accumulation in the
sediment may reach amounts sufficient to cause reduced survival for benthic invertebrates.
Additionally, the sediment may be resuspended causing lotic, as well as benthic organisms to
be exposed. As shown in Figure 8-4, the Mississippi Cotton scenario suggests that, without
sediment burial, in approximately 15 years sufficient accumulation could be present in amounts
that caused 84% mortality to the amphipod (Hyalella azteca) in a laboratory study. Relevant
amounts of accumulation may take years to occur, but could potentially place benthic
organisms at risk.
51
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Mississippi Cotton
00
—
ao
£,
c
o
5
to
4->
c
0)
u
c
o
u
4->
c
0)
£
ai
to
160
140
120
100
80
60
40
20
¦ No Sediment Burial
¦ Hyalella NOAEC
¦ Leptocheirus NOAEC
¦With Sediment Burial
Chironomous NOAEC
¦ Hyalella LOAEC 84% Mortality
TT
i
i
i
J
1 1
^ !!
—
—/m
1
1
1
1
1
1
1
1
1
—
0
1/1/61 1/1/65 1/1/69 1/1/73 1/1/77 1/1/81 1/1/85 1/1/89 1/1/93
Date
Florida Turf
00
—
ao
E,
c
o
to
4->
c
0)
u
c
o
u
4->
c
0)
E
'S
a>
tO
160
140
120
100
80
60
40
20
—
No Sediment Burial With Sediment Burial
— Hyalella NOAEC — Chironomous NOAEC
— Leptocheirus NOAEC = = Hyalella LOAEC 84% Mortality
¦ —
0
1/1/61 1/1/65 1/1/69 1/1/73 1/1/77 1/1/81 1/1/85 1/1/89 1/1/93
Date
Figure 8-4. Comparison of Sediments Estimated Environmental Concentrations to Chronic
Effects Endpoints for Two Scenarios with and without Sediment Burial Implemented based on
a 1.0 lbs ai/A Application Rate
8.2.3 Aquatic Plants
Risk estimates showed LOC exceedances (RQs of 4-26) to non-vascular aquatic plants (algae)
from all registered uses of paraquat and all application rates. Vascular plants were less sensitive
and had no LOC exceedances.
52
-------
Table 8-10. Aquatic Plant Risk Quotients for Non-Listed Species
Use Sites
Application Method
Peak EEC
Hg/L
Risk Quotients
Vascular
Non-vascular
IC50 = 71
|ig cation/L
IC50 = 0.40
|ig cation/L
Alfalfa and Clover, 1.5 lb
cation/A
Aerial
10.5
0.15
26
Ground
5.2
0.07
13
Multiple Uses, Higher
Application Rate, 1.01 lb
cation/A
Aerial
7.1
0.10
18
Ground
3.5
0.05
8.8
Multiple Uses, Lower
Application Rate, 0.5 lb
cation/A
Aerial
3.5
0.05
8.8
Ground
1.7
0.02
4.3
Bolded values exceed the LOC for non-listed plants of 1. The endpoints listed in the table are the endpoint used to
calculate the RQ.
The low RQs for aquatic vascular plants are somewhat surprising, given that Lemna has been
studied for use in bioassays for determining the presence of paraquat (Funderburk and
Lawrence, 1963, and Kamanakis, 1970), with growth expressed as dry weight of Lemna, as a
consistent indicator of paraquat.
Further investigation shows that when Lemna toxicity endpoints (EC50 of 71 |ag cation/L; MRID
42601003) are compared with a range of algal toxicity endpoints (ranging from Navicula EC50 of
0.40 |ag cation/L to Chlorococcum EC50 of 36,000 |ag cation/L, MRIDs 42601006 and 40228401),
Lemna is among the more sensitive aquatic plant species, with two of eight algal species tested
having a more sensitive ECsothan Lemna, the others less sensitive.
The weight of evidence shows that aquatic plants can be affected by paraquat exposure, but
the amount of bioavailable paraquat to which they are exposed is difficult to predict. As
previously discussed, paraquat's strong adsorption to particles or sediment, likely reduces its
bioavailability to aquatic plants. Conversely, paraquat has been reportedly used for aquatic
weed control, although this use is not registered in the U.S. (Ogamba, etal., 2011; Zaranyika
and Nyoni, 2013). Potential effects likely depend on spray drift, rather than runoff, as discussed
earlier for all aquatic exposure. The presence of dissolved or particulate matter may also
influence the amount of paraquat that reaches aquatic plant tissue.
Therefore, based on the available data, risk to aquatic plants is expected from the use of
paraquat.
53
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restrial Vertebrates Risk Assessment
9.1 Terrestrial Vertebrate Exposure Assessment
Terrestrial wildlife exposure estimates are typically calculated for birds and mammals by
emphasizing the dietary exposure pathway. Paraquat is applied through aerial and ground
application methods, which includes banded and broadcast sprayers, spot-treatment sprays
and a tree wound treatment. No seed treatments or granular products are currently registered,
and so dietary exposure does not include calculations for treated seeds or granules.
Additionally, due to low bioaccumulation potential (see footnotes to Table 7-1), dietary
exposure does not include calculations for consumption of aquatic organisms. Therefore,
potential dietary exposure for terrestrial wildlife in this assessment is based on consumption of
paraquat residues on food items following spray (foliar or soil) applications.
9.1.1 Dietary Items on the Treated Field
Potential dietary exposure for terrestrial wildlife in this assessment is based on consumption of
paraquat residues on food items following spray (foliar or soil) applications. EECs for birds (also
used as a proxy for reptiles and terrestrial-phase amphibians) and mammals from consumption
of dietary items on the treated field were calculated using T-REX v.1.5.2 and based on
application rates, number of applications, and intervals presented in Table 3-1. The default
foliar dissipation half-life of 35 days was used here in the absence of chemical-specific foliar
dissipation data, and given paraquat's stability, without information showing that at least three
foliar dissipation half-lives are greater than 35 days (so that a longer half-life could be used in
the calculations), the 35-day default is used here, but some uncertainty is acknowledged (per
TREX user guide, USEPA, 2012c). However, because a single application triggered risk concerns
for both birds and mammals, additional information would not likely change the risk
conclusions.
Upper-bound Kenaga nomogram values are used to derive EECs for paraquat exposures to
terrestrial mammals and birds on the field of application based on a 1-year time period, and
also for a single application at the lower (0.50 lb cation/A) and higher (1.01 lb cation/A)
application rates common for most uses. Consideration is given to different types of feeding
strategies for mammals, including herbivores, insectivores and granivores. Dose-based
exposures are estimated for three weight classes of birds (20 g, 100 g, and 1,000 g) and three
weight classes of mammals (15 g, 35 g, and 1,000 g). EECs on terrestrial food items range from 8
to 242 mg cation/kg-diet for a single application and from 25 to 1620 mg cation/kg-diet for the
maximum number of applications, based on upper bound Kenaga values. Dose-based EECs,
adjusted for body weight, range from 0.5 to 1840 mg cation/kg-bw for birds and 0.3 to 1540 mg
cation/kg-bw for mammals. A summary of EECs is found in Table 9-1 (also see Appendix D).
54
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Table 9-1. Summary of Dietary (mg a.i./kg-diet) and Dose-Based EECs (mg a.i./kg-bw) as Food Residues for Birds, Reptiles,
Terrestrial-Phase Amphibians and Mammals from Labeled Uses of Paraquat (T-REX v. 1.5.2, Upper Bound Kenaga)
Food Type
Dietary-Based
EEC (mg
cation/kg-diet)
Dose-Based EEC (mg cation/kg-body weight)
Birds
Mammals
Small
(20 g)
Medium
(100 g)
Large
(1000 g)
Small
(15 g)
Medium
(35 g)
Large
(1000 g)
Alfalfa and Clover (1.5 lb cation/acre, lx per crop cycle, interval not specified; modeled 3x annually with 120-day interval)1
Short grass
397
452
258
115
378
261
60.6
Tall grass
182
207
118
52.9
173
120
27.8
Broadleaf plants/small insects
223
254
145
64.9
213
147
34.1
Fruits/pods/(seeds, dietary only)
24.8
28.2
16.1
7.21
23.6
16.3
3.79
Arthropods
155
177
101
45.2
148
102
23.7
Seeds (granivore)
24.8
6.27
3.58
1.60
5.25
3.63
0.84
Premises/Areas (1.01 lb cation/A, lOx, 7-day interval)2
Short grass
1400
1600
912
408
1340
925
215
Tall grass
644
733
418
187
614
424
98.3
Broadleaf plants/small insects
790
900
513
230
753
521
121
Fruits/pods/(seeds, dietary only)
87.8
100
57.0
25.5
83.7
57.8
13.4
Arthropods
550
626
357
160
524
362
84.0
Seeds (granivore)
87.8
22.2
12.7
5.67
18.6
12.9
2.98
Multiple Ag and Non-Ag Uses (1.01 lb cation/A, 5x, 7-day interval)3
Short grass
936
1070
608
272
893
617
143
Tall grass
429
489
279
125
409
283
65.6
Broadleaf plants/small insects
527
600
342
153
502
347
80.5
Fruits/pods/(seeds, dietary only)
58.5
66.7
38.0
17.0
55.8
38.6
8.94
Arthropods
367
418
238
107
350
242
56.0
Seeds (granivore)
58.5
14.8
8.45
3.78
12.4
8.57
1.99
Single App. Most Common Rate (1.01 lb cation/A)
Short grass
242
276
157
70.5
231
160
37.0
Tall grass
111
127
72.2
32.3
106
73.2
17.0
Broadleaf plants/small insects
136
155
88.6
39.7
130
89.9
20.8
Fruits/pods/(seeds, dietary only)
15.2
17.3
9.84
4.41
14.4
9.98
2.31
Arthropods
94.9
108
61.7
27.6
90.5
62.6
14.5
Seeds (granivore)
15.2
3.83
2.19
0.98
3.21
2.22
0.51
55
-------
Food Type
Dietary-Based
EEC (mg
cation/kg-diet)
Dose-Based EEC (mg cation/kg-body weight)
Birds
Mammals
Small
(20 g)
Medium
(100 g)
Large
(1000 g)
Small
(15 g)
Medium
(35 g)
Large
(1000 g)
Single App. Lowest Rate (0.50 lb cation/A)4
Short grass
120
137
77.9
34.9
114
79.1
18.3
Tall grass
55.0
62.6
35.7
16.0
52.4
36.2
8.40
Broadleaf plants/small insects
67.5
76.9
43.8
19.6
64.4
44.5
10.3
Fruits/pods/(seeds, dietary only)
7.50
8.54
4.87
2.18
7.15
4.94
1.15
Arthropods
47.0
53.5
30.5
13.7
44.8
31.0
7.18
Seeds (granivore)
7.50
1.90
1.08
0.48
1.59
1.10
0.25
1Alfalfa has a 1.5 lb a.e./acre max with 1 app. per crop cycle, and specifies 3 applications per year, but also has a 2 lb a.e./acre annual max, so although this
screening for alfalfa and clover is represented here using 3 apps, the annual amount is over-estimated for alfalfa. The clover use does not currently specify the
annual number of applications or the annual maximum amount.
2Premises/Areas included outdoor occupational, manufacturing, processing or industrial areas using a ground sprayer. These did not specify the intervals or
any type of seasonal limits so a 7-day application interval was conservatively assumed. They specify a max. single app. rate of 1.01 lb a.e./A and a max. of 10
apps annually.
3Many agricultural and forestry uses have a maximum single app. rate of 1.01 lb a.e./A and specify either 1, 2, 3, 4, or 5 apps annually—5 apps are used here
for screening, with the exception that a single app. is also modeled. Like the premises/areas use, these uses did not specify the intervals or any type of seasonal
limits so a 7-day interval was assumed (based on recommendations from BEAD). Uses with a max. of 5 apps include: acerola, almond, apple, avocado, banana,
bushberries, caneberries, citrus, cocoa, coffee, figs, grapes, papaya, passion fruit, pear, persimmon, pistachio, prune, tree nuts, and various non-food trees.
4 The 0.5 lb cation/A application rate applies to beans, guar, hops, lentils, peas, strawberries, tuberous and corm vegetables and pastureland/rangeland uses.
One use, for macadamia nuts, actually has a slightly lower application rate (0.475 lb cation/A), but this was not modeled.
56
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9.2 Terrestrial Vertebrate Risk Characterization
RQ values are generated based on the upper bound EECs discussed above and toxicity values
contained in Table 6-2.
For acute dose-based exposure for birds and mammals, RQ values range from 0.01 to 57 (Table
9-2 and Table 9-3, also see Appendix D). For birds, RQs exceed the LOC for most feeding groups
of non-listed birds for all uses, with the exception that for granivores, only the smallest size
class have LOC exceedances, and only with multiple applications with a 7-day re-application
interval. For mammals, acute RQs exceed the LOC for groups of non-listed mammals feeding on
grasses, broadleaf plants and arthropods for all uses. Considering specifically a single
application at the most common maximum application rate for most agricultural and non-
agricultural uses (1.01 lb cation/A), most feeding groups of birds have exceedances, but only
mammals feeding on grasses and broadleaf plants exceed the LOC. For the lower single
application rate of 0.5 lb cation/A, only birds feeding on grasses, broadleaf plants, and
arthropods had exceedances, and only the smallest size class of mammals feeding on short
grasses had exceedances.
For acute dietary-based exposures for birds, RQs range from 0.01 to 2.0 (Table 9-2) based on
upper bound values. For all uses, birds feeding on short grass had exceedances; for multiple
applications modeled using a 7-day re-application interval (premises/areas and multiple
agricultural and non-agricultural uses), birds feeding on grasses, broadleaf plants, and
arthropods also had LOC exceedances.
For chronic exposures for birds, dietary based RQs (Table 9-2) were based on significant
(p<0.05) reductions in reproduction and food consumption (mallard reductions of 59.0 % in
eggs laid, 24.7% in viable embryos/egg set, 33.1% in live embryos/egg set, and 8.5% in mean
food consumption, MRID 00110455). RQs ranging from 0.26 to 48 based on upper bound values
exceed the LOC in all feeding groups and for all uses, except that no exceedances were found
for granivores and fruits/pods/seeds consumers with a single application, or for granivores with
the longer (120-day) re-application interval (applying to alfalfa and clover).
For chronic exposures for mammals, dietary-based RQs (Table 9-4) were based on no
measurable effects in rat reproductive or offspring body weight at the highest treatment level
tested (7.5 mg cation/kg-bw, 108 kg cation/kg-diet, MRID 43685001). RQs ranged from 0.04 to
81 and show that RQs do not exceed the LOC from a single application for granivores (all uses
except premises/areas use and smallest size class), and fruit/pod/seed consumers. For bolded
values, these show that risk cannot be precluded for all size classes feeding on grasses,
broadleaf plants and arthropods, from both dose-based and most dietary-based estimates.
57
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Table 9-2. Acute and Chronic RQs for Birds, Reptiles, and Terrestrial-Phase Amphibians from
Labeled Uses of Paraquat (T-REX v. 1.5.2, Upper Bound Kenaga)
Acute Dose-Based RQ
Acute Dietary-
Chronic Dietary
Food Type
LDso =
26.5 mg cation/kg-bw
Based RQ
RQ
Small
Medium
Large
LCso = 698
NOAEC = 29.4 mg
(20 g)
(100 g)
(1000 g)
mg cation/kg-diet
cation/kg-diet
Alfalfa and Clover (1.5 lb cation/acre, 3x, 120-day interval)1
Herbivores/lnsectivores
Short grass
16.2
7.26
2.30
0.57
13.5
Tall grass
7.43
3.33
1.05
0.26
6.18
Broadleaf plants
9.12
4.08
1.29
0.32
7.59
Fruits/pods
1.01
0.45
0.14
0.04
0.84
Arthropods
6.35
2.84
0.90
0.22
5.28
Granivores
Seeds
0.23
0.10
0.03
0.04
0.84
Premises/Areas (1.01 lb cation/A, lOx, 7-day interval)
Herbivores/lnsectivores
Short grass
57.4
25.7
8.15
2.01
47.8
Tall grass
26.3
11.8
3.73
0.92
21.9
Broadleaf plants
32.3
14.5
4.58
1.13
26.9
Fruits/pods/seeds
3.59
1.61
0.51
0.13
2.99
Arthropods
22.5
10.1
3.19
0.79
18.7
Granivores
Seeds
0.80
0.36
0.11
0.13
2.99
Multiple Ag and Non-Ag Uses (1.01 lb cation/A, 5x, 7-day interval)
Herbivores/lnsectivores
Short grass
38.3
17.1
5.43
1.34
31.9
Tall grass
17.5
7.86
2.49
0.61
14.6
Broadleaf plants
21.5
9.64
3.06
0.75
17.9
Fruits/pods/seeds
2.39
1.07
0.34
0.08
1.99
Arthropods
15.0
6.71
2.13
0.53
12.5
Granivores
Seeds
0.53
0.24
0.08
0.08
1.99
Single App. (1.01 lb cation/A)
Herbivores/lnsectivores
Short grass
9.91
4.44
1.41
0.35
8.24
Tall grass
4.54
2.03
0.64
0.16
3.78
Broadleaf plants
5.57
2.50
0.79
0.20
4.64
Fruits/pods/seeds
0.62
0.28
0.09
0.02
0.52
Arthropods
3.88
1.74
0.55
0.14
3.23
Granivores
Seeds
0.14
0.06
0.02
0.02
0.52
Single App. Lower Rate (0.50 lb cation/A)
Herbivores/lnsectivores
Short grass
4.90
2.20
0.70
0.17
4.08
Tall grass
2.25
1.01
0.32
0.08
1.87
58
-------
Acute Dose-Based RQ
Acute Dietary-
Chronic Dietary
Food Type
LDso =
26.5 mg cation/kg-bw
Based RQ
RQ
Small
Medium
Large
LCso = 698
NOAEC = 29.4 mg
(20 g)
(100 g)
(1000 g)
mg cation/kg-diet
cation/kg-diet
Broadleaf plants
2.76
1.24
0.39
0.10
2.30
Fruits/pods/seeds
0.31
0.14
0.04
0.01
0.26
Arthropods
1.92
0.86
0.27
0.07
1.60
Granivores
Seeds
0.07
0.03
0.01
0.01
0.26
Bolded values exceed the LOC for acute risk to non-listed species of 0.5 or the chronic risk LOC of 1.0. The endpoints listed in
the table are the endpoint used to calculate the RQ.
Toxicity endpoints used in RQ calculations: Zebra Finch LD50 (MRID 49349901, bird weight of 14.3g used in T-REX); Japanese
Quail LC50 (MRID 00022923, bird weight of 43g used in T-REX) and Mallard Duck NOAEC (MRID 00110455) based on significant
(p<0.05) reductions in reproduction and food consumption (59.0 % in eggs laid, 24.7% in viable embryos/egg set, 33.1% in live
embryos/egg set, and 8.5% in mean food consumption).
1Alfalfa has a 1.5 lb a.e./A max with 1 app. per crop cycle, and specifies 3 apps per year, but also has a 2 lb a.e./A annual max, so
although this screening for alfalfa and clover is represented here using 3 apps, the ann. amount is over-estimated for alfalfa.
The clover use does not currently specify the ann. no. of apps or the ann. max. amount.
Table 9-3. Acute RQs for Mammals from Labeled Uses of Paraquat (T-REX v. 1.5.2, Upper
Bound Kenaga)
Food Type
Acute Dose-Based RQ
LDso = 93 mg cation/kg-bw
Acute Dietary-Based RQ
Data Unavailable
Small (15 g)
Medium (35 g)
Large (1000 g)
Alfalfa and Clover (1.5 lb cation/acre, 3x, 120-day interval)1
Herbivores/lnsectivores
Short grass
1.85
1.58
0.85
-
Tall grass
0.85
0.72
0.39
-
Broadleaf plants
1.04
0.89
0.48
-
Fruits/pods/seeds
0.12
0.10
0.05
-
Arthropods
0.72
0.62
0.33
-
Granivores
Seeds
0.03
0.02
0.01
-
Premises/Areas (1.01 lb cation/A, lOx, 7-day interval)
Herbivores/lnsectivores
Short grass
6.55
5.60
3.00
-
Tall grass
3.00
2.56
1.37
-
Broadleaf plants
3.68
3.15
1.69
-
Fruits/pods/seeds
0.41
0.35
0.19
-
Arthropods
2.57
2.19
1.17
-
Granivores
Seeds
0.09
0.08
0.04
-
Multiple Ag and Non-Ag Uses (1.01 lb cation/A, 5x, 7-day interval)
Herbivores/lnsectivores
Short grass
4.37
3.73
2.00
-
Tall grass
2.00
1.71
0.92
-
Broadleaf plants
2.46
2.10
1.12
-
Fruits/pods/seeds
0.27
0.23
0.12
-
59
-------
Food Type
Acute Dose-Based RQ
LDso = 93 mg cation/kg-bw
Acute Dietary-Based RQ
Data Unavailable
Small (15 g)
Medium (35 g)
Large (1000 g)
Arthropods
1.71
1.46
0.78
-
Granivores
Seeds
0.06
0.05
0.03
-
Single App. (1.01 lb cation/A)
Herbivores/lnsectivores
Short grass
1.13
0.97
0.52
-
Tall grass
0.52
0.44
0.24
-
Broadleaf plants
0.64
0.54
0.29
-
Fruits/pods/seeds
0.07
0.06
0.03
-
Arthropods
0.44
0.38
0.20
-
Granivores
Seeds
0.02
0.01
0.01
-
Single App. Lower Rate (0.50 lb cation/A)
Herbivores/lnsectivores
Short grass
0.56
0.48
0.26
-
Tall grass
0.26
0.22
0.12
-
Broadleaf plants
0.31
0.27
0.14
-
Fruits/pods/seeds
0.03
0.03
0.02
-
Arthropods
0.22
0.19
0.10
-
Granivores
Seeds
0.01
0.01
<0.01
-
Bolded values exceed the LOC for acute risk to non-listed species of 0.5. The endpoints listed in the table are the endpoint used
to calculate the RQ.
Toxicity endpoint used in RQ calculations: Rat LD50 (MRID 43685001).
1Alfalfa has a 1.5 lb a.e./A max with 1 app. per crop cycle, and specifies 3 apps per year, but also has a 2 lb a.e./A annual max, so
although this screening for alfalfa and clover is represented here using 3 apps, the ann. amount is over-estimated for alfalfa.
The clover use does not currently specify the ann. no. of apps or the ann. max. amount.
60
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Table 9-4. Chronic RQs for Mammals from Labeled Uses of Paraquat (T-REX v. 1.5.2, Upper
Bound Kenaga)
Food Type
RQs Based on Multi-Gen. Rat Study
Additional Line-of-Evidence
Exposure:Effect Ratios (RQ Estimates)
Based on Pre-Natal Data NOAEL = 1
mg cation/kg-bw1
Chronic Dose-Based RQ
NOAEL = 7.5 mg cation/kg-bw1
Chronic
Dietary RQ
NOAEC=
108
mg
cation/kg-
diet1
Small
(15 g)
Medium
(35 g)
Large
(1000 g)
Small
(15 g)
Medium
(35 g)
Large
(1000 g)
Alfalfa and Clover (1.5 lb cation/acre, 3x, 120-day interval)2
Herbivores/lnsectivores
Short grass
22.9
19.6
10.5
3.67
172
147
78.8
Tall grass
10.5
8.98
4.81
1.68
78.8
67.4
36.1
Broadleaf plants
12.9
11.0
5.91
2.07
96.8
82.7
44.3
Fruits/pods/seeds
1.43
1.22
0.66
0.23
10.8
9.18
4.92
Arthropods
8.98
7.67
4.11
1.44
67.4
57.6
30.9
Granivores
Seeds
0.32
0.27
0.15
0.23
2.39
2.04
1.09
Premises/Areas (1.01 lb cation/A, lOx, 7-day interval)
Herbivores/lnsectivores
Short grass
81.2
69.4
37.2
13.0
609
520
279
Tall grass
37.2
31.8
17.1
5.96
279
239
128
Broadleaf plants
45.7
39.0
20.9
7.31
343
293
157
Fruits/pods/seeds
5.08
4.34
2.32
0.81
38.1
32.5
17.4
Arthropods
31.8
27.2
14.6
5.09
239
204
109
Granivores
Seeds
1.13
0.96
0.52
0.81
8.46
7.23
3.87
Multiple Ag and Non-Ag Uses (1.01 lb cation/A, 5x, 7-day interval)
Herbivores/lnsectivores
Short grass
54.2
46.3
24.8
8.67
406
347
186
Tall grass
24.8
21.2
11.4
3.97
186
159
85.2
Broadleaf plants
30.5
26.0
14.0
4.88
228
195
105
Fruits/pods/seeds
3.38
2.89
1.55
0.54
25.4
21.7
11.6
Arthropods
21.2
18.1
9.71
3.40
159
136
72.8
Granivores
Seeds
0.75
0.64
0.34
0.54
5.64
4.82
2.58
Single App. (1.01 lb cation/A)
Herbivores/lnsectivores
Short grass
14.0
12.0
6.42
2.24
105
89.8
48.2
Tall grass
6.43
5.49
2.94
1.03
48.2
41.2
22.1
Broadleaf plants
7.89
6.74
3.61
1.26
59.2
50.5
27.1
Fruits/pods/seeds
0.88
0.75
0.40
0.14
6.57
5.61
3.01
Arthropods
5.49
4.69
2.51
0.88
41.2
35.2
18.9
Granivores
Seeds
0.19
0.17
0.09
0.14
1.46
1.25
0.67
61
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Single App. Lower Rate (0.50 lb cation/A)
Herbivores/lnsectivores
Short grass
6.94
5.93
3.18
1.11
18.4
15.8
8.44
Tall grass
3.18
2.72
1.46
0.51
7.81
6.67
3.58
Broadleaf plants
3.90
3.33
1.79
0.63
9.76
8.34
4.47
Fruits/pods/seeds
0.43
0.37
0.20
0.07
1.52
1.30
0.70
Arthropods
2.72
2.32
1.24
0.44
14.1
12.0
6.46
Granivores
Seeds
0.10
0.08
0.04
0.07
0.34
0.29
0.15
Bolded values exceed the chronic risk LOC of 1.0. The endpoints listed in the table are the endpoint used to calculate the RQ.
1The toxicity endpoint used in RQ calculations, Rat LD50 (MRID 43685001), had no measurable effects in reproductive or
offspring body weight at the highest treatment level of 7.5 mg cation/kg-bw (108 mg cation/kg-diet). Due to the non-definitive
LOAEC.and additional line-of-evidence was added by estimating risk using a growth endpoint from a prenatal developmental
study.
2Alfalfa has a 1.5 lb a.e./A max with 1 app. per crop cycle, and specifies 3 apps per year, but also has a 2 lb a.e./A annual max, so
although this screening for alfalfa and clover is represented here using 3 apps, the ann. amount is over-estimated for alfalfa.
The clover use does not currently specify the ann. no. of apps or the ann. max. amount.
In characterizing terrestrial vertebrate risk, consideration is given here to available options,
chiefly the effect on risk conclusions if mean Kenaga residues are considered, rather than upper
Kenaga residues, and if avian LOAEC, rather than NOAEC, is considered.
For mammals, dietary based RQs (Table 9-4) were based on no measurable effects in rat
reproductive or offspring weight at the highest treatment level tested (as mentioned above).
This was approximately the same dietary level that caused chronic effects to reproduction and
food consumption in birds (108 kg cation/kg-diet for rats vs. 101 mg cation/kg-diet for birds,
MRIDs 43685001 and 00110455). Many of the chronic RQs calculated here are above 1 because
the highest dose tested was below the highest predicted exposure level. The RQs can
definitively show cases where risk does not exceed the LOC; this mainly applies to granivores,
but also to fruit/pod/seed consumers from a single application. The LOC exceedances show
where risk cannot be precluded but do not confirm risk; this applies to all size classes feeding
on grasses, broadleaf plants and arthropods, from both dose-based and most dietary-based
estimates. Therefore, the specific chronic-exposure risk to mammals from the use of paraquat
is uncertain.
For mammals, use of mean, rather than upper bound Kenaga only produced LOC exceedances
for chronic dose-based risk and because the chronic study was non-definitive, the results are
not presented here, but the information can be found in Appendix D. However, using the mean
Kenega exposure estimates with the rat prenatal growth endpoint, the lowest single application
rate (0.5 lb cation/A) had LOC exceedances for all feeding groups except granivores (RQs ranged
from 0.15 to 18). Further analyses may be done at the request of risk managers if deemed to be
helpful.
62
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The bird data is more conducive to this type of characterization. If risk calculations are based on
mean Kenaga, rather than upper Kenaga, a single application at the lowest application rate of
0.50 lb cation/A will still cause LOC (0.5) exceedances for small and medium birds feeding on
short grass and small birds feeding on tall grass, broadleaf plants and arthropods from dose-
based toxicity data. From dietary-based toxicity data, the lowest application rate does not
cause acute LOC exceedances, but does cause chronic LOC (1) exceedances for birds feeding on
short grass and arthropods (Table 9-5, also see Appendix D for the output showing EECs and
additional information). Therefore, even using the lowest single application rate and mean,
rather than upper, Kenaga exposure estimates, acute risk is still identified for some feeding
groups of small and medium birds, and possibly chronic risk for all sizes.
Table 9-5. Acute and Chronic RQs for Birds, Reptiles, and Terrestrial-Phase Amphibians from
Lowest Single Application of Paraquat Using Mean Kenaga Values
Food Type
Acute Dose-Based RQ
LDso = 26.5 mg cation/kg-bw
Acute Dietary-
Based RQ
LCso = 698
mg cation/kg-diet
Chronic Dietary
RQ
NOAEC = 29.4 mg
cation/kg-diet
Small
(20 g)
Medium
(100 g)
Large
(1000 g)
Single App. Lower Rate (0.50 lb cation/A)
Herbivores/lnsectivores
Short grass
1.74
0.78
0.25
0.06
1.45
Tall grass
0.74
0.33
0.10
0.03
0.61
Broadleaf plants
0.92
0.41
0.13
0.03
0.77
Fruits/pods
0.14
0.06
0.02
0.01
0.12
Arthropods
1.33
0.59
0.19
0.05
1.11
Granivores
Seeds
0.03
0.01
<0.01
0.01
0.12
Bolded values exceed the LOC for acute risk to non-listed species of 0.5 or the chronic risk LOC of 1.0. The
endpoints listed in the table are the endpoint used to calculate the RQ.
Toxicity endpoints used in RQ calculations: Zebra Finch LDso (MRID 49349901); Japanese Quail LCso (MRID
00022923) and Mallard Duck NOAEC (MRID 00110455).
For birds, the chronic study was definitive and so, the mallard LOAEC could be used to further
characterize risk from paraquat use. For mammals, this comparison was not made here because
the chronic study was non-definitive. The mallard LOAEC (see Table 6-2) was based on
significant (p<0.05) reductions of 59.0 % in eggs laid, 24.7% in viable embryos/egg set, 33.1% in
live embryos/egg set, and 8.5% in mean food consumption (MRID 00110455). This analysis
shows that the estimated exposure (EECs) are at risk of exceeding the LOAEC by 2-14X for some
feeding groups of birds, where effects would be expected to occur, from the highest multiple
application rate (1.01 lb cation/A at 10 applications with 7-day intervals, Table 9-6). A single
application at the highest and lowest rate (1.01 and 0.5 lb cation/A) would be expected to
exceed the LOAEC for some feeding groups if upper Kenega values are considered, but not if
only mean Kenaga values are considered.
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Table 9-6. Chronic RQs for Birds from Highest Multiple and Highest and Lowest Single
Application of Paraquat Based on Mallard LOAEC Using Both Upper and Mean Kenaga Values
Food Type
Chronic Dietary RQ based on Mallard LOAEC = 101 mg cation/kg-diet
Highest Multiple App. Rate (1.01 lb
cation/A, lOx, 7-day interval))
Single App. Highest/Lowest Rates
(1.01/0.50 lb cation/A)
Mean Kenaga EECs
Upper Kenaga EECs
Mean Kenaga EECs
Upper Kenaga EECs
Herbivores/lnsectivores
Short grass
4.92
13.9
0.85/0.42
2.40/1.19
Tall grass
2.09
6.37
0.36/0.18
1.10/0.54
Broadleaf plants
2.61
7.82
0.45/0.22
1.35/0.67
Fruits/pods
0.41
0.87
0.07/0.03
0.15/0.07
Arthropods
3.77
5.45
0.65/0.32
0.94/0.47
Granivores
Seeds
0.41
0.87
0.07/0.03
0.15/0.07
Bolded values exceed the LOC for acute risk to non-listed species of 0.5 or the chronic risk LOC of 1.0. The
endpoints listed in the table are the endpoint used to calculate the RQ.
Toxicity endpoints used in RQ calculations: Zebra Finch LDso (MRID 49349901); Japanese Quail LCso (MRID
00022923) and Mallard Duck NOAEC (MRID 00110455).
Although the above analysis shows that multiple applications of paraquat are likely to exceed
the mallard LOAEC by up to 14X, some uncertainty is acknowledged over whether chronic risk
would be likely due to rapid plant death. For animals feeding on living plants, rapid plant death
from paraquat exposure may make plants unpalatable and so chronic exposure may be unlikely.
This uncertainty is limited to plant-eaters and would not apply to consumers of fruits, grains,
seeds, or arthropods.
For acute effects, however, the analysis described above strongly suggests that effects are likely
to occur, in that even a single application at the lowest application rate (0.5 lb cation/A), and
based on mean, rather than upper, Kenaga values, still exceeds the LOC for most feeding
groups of small-sized birds and two feeding groups of medium-sized birds (Table 9-5).
In two non-guideline studies, a formulated product containing paraquat dichloride was sprayed
onto the eggs of pheasant (MRID 43942605) and mallard ducks (MRID 43942604). In the
pheasant study, a decrease in the number of eggs hatched and the number of 28-d old
survivors was observed at 1.0 lb cation/A, resulting in a study NOAEC of 0.5 lb cation/A. In the
mallard study, an application rate of 2.0 lb cation/A increased the number of embryonic deaths
(at days 13 and 19) as well as the number of dead embryos in the shell at day 31. At this
concentration, the number of hatchlings and number of chicks surviving to 28 d were also
decreased. The resulting NOAEC was 1.0 lb cation/A. This suggests that application timing may
be important in preventing reproduction effects to birds and other egg-laying animals, and
likely also to live-bearing animals.
64
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Incidents reviewed above in Section 6.3, suggest potential for harm to non-target terrestrial
animals from exposure to paraquat. For birds, three bird-kill incidents were found in the
database that actually occurred outside the U.S. (1021685-002,1021848-003, and 1021848-004)
and so cannot be attributed to registered use, but do support a line of evidence that paraquat
can be toxic to birds. One domestic bird incident involving the deaths of five Canada geese
(1008168-001) was from a registered use on corn and of probable causality, but also involved
other pesticides; however, as previously mentioned, paraquat was considered to be the
pesticide present in the tank mix at an amount representing the highest acute toxicity to birds.
Another incident with a causality of probable for paraquat involved the deaths two unknown
species (four individuals) of birds (1007344-001), but the legality of use was undetermined.
Similarly, incidents that were of undetermined legality involved mortality of dogs (1020627-033
and 1027242-001; 1027242-001 occurred outside of the U.S.) and cannot be attributed to
registered use, but do support a line of evidence that paraquat can be toxic to mammals.
These incidents, along with multiple LOC exceedances for birds and mammals strongly support
risk to terrestrial vertebrates. In some cases, however, the level of risk is uncertain due to
either uncertainty in effects or exposure. The chief effects uncertainty is limited to mammalian
chronic risk, as described above, where the highest dose tested in the rat reproduction study
was below the highest predicted exposure level, and, therefore, the specific risk
to mammals from the use of paraquat is uncertain. In the absence of data definitive LOAEC,
where the RQ was greater than 1, risks to mammal species are assumed. The added value of
obtaining a definitive LOAEC, however, would not greatly affect the risk conclusions even if
many of the feeding groups dropped below the chronic LOC because acute LOCs were also
exceeded for most feeding groups and registered use application rates.
There was uncertainty in the exposure estimates pertaining to repeated applications, partly
because the labels did not specify a re-application interval for many labeled uses. As a result, a
7-day interval was conservatively assumed. Also, the foliar dissipation half-life for paraquat was
uncertain. No foliar dissipation study was available for use and, due to the persistence of
paraquat (years), the 35-day T-REX default half-life was used because theoretically, the food
items on which paraquat would be present would not remain in the environment for the
longevity of the chemical, or would be expected to be washed off by rain. EPA policy (USEPA,
2012c) is to use the default half-life unless at least three chemical-specific foliar dissipation half-
lives are readily available, and values are >35 days. Further information on the length of time
paraquat can reasonably be expected to remain on food items, such as leaf surfaces, is
sometimes obtained from magnitude of residue studies used in tolerance determinations
(USEPA, 1995). Half-lives were not calculated from the original studies at this time because LOC
exceedances were found with a single application, even at the lowest application rate (0.5 lb
cation/A). Refined information on the foliar dissipation half-life either from residue or foliar
dissipation studies might reduce uncertainty; however, this additional information would not
65
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likely change the risk conclusions because a single application triggered risk concerns for both
birds and mammals.
Based on the available data, risks to birds and mammals from the use of paraquat are expected
with acute RQs as high as 57 for birds and 7 for mammals. Although the RQs are lower for single
applications, the acute dose-based RQ is still 10 times the LOC for small birds feeding on short
grass. Chronic risk to birds is also high with RQs as high as 48, based on significant effects to
mallard reproduction and food consumption. For mammals, the chronic risk was less certain
with RQs as high as 81, based on a no-effect level from a rat 3-generation study. However, an
additional line-of-evidence was used by estimating risk using rat prenatal growth data, which
showed LOC exceedances for all uses. Chronic risk to mammals was identified for all uses, with
the exception of some feeding groups from a single application. More information on chronic
mammalian reproduction effects would not greatly affect the risk conclusions due to the acute
risk picture and results of risk estimates using rat prenatal growth data. Incident data were
available for both birds and mammals that show the potential for mortality from paraquat
exposure, though the association with registered uses was not clear.
A further point to consider in characterizing chronic dietary risk to terrestrial vertebrates is
whether the food items sprayed with paraquat would be palatable on a chronic exposure basis.
Because paraquat is a desiccant, animals consuming grasses and broadleaf plants might be
more at risk from acute exposure than chronic exposure because the palatability of the plants
would likely decrease as the plant food items desiccate. However, the desiccating action is not
sufficiently rapid to eliminate the exposure pathway. Rapid wilting and desiccation begin within
hours of application in full sunlight when paraquat produces superoxide radicals that disrupt
the plasma membrane and the cell contents leak out. The leaves go from soft and turgid to dry
and desiccated in a matter of days, with complete foliar necrosis occurring in 1 to 3 days and,
for some plant species, leaves fall off in the final stages (2014, Shaner; BEAD, personal
communication5). The net result could be similar to non-chemical control methods that involve
plowing-under and mowing (BEAD, personal communication5). It's possible that, in some cases,
the lower plant weight due to desiccation may result in more plants being consumed by the
animal and, where food alternatives are limited, the exposure may be increased. In the case of
nuts, seeds, and arthropods (and possibly fruits) palatability would not likely be altered by
desiccation in the same way as that described for foliage. Therefore, for food items in the
treated area, the chronic risk to grass and broadleaf consuming mammals, birds, and reptiles
5 BEAD. 2019. Personal communication between Bill Chism, Senior Biologist, Biological and Economic Analysis
Division and Marianne Mannix, Chemical Review Manager, Pesticide Re-registration Division, Office of Pesticide
Programs, U.S. Environmental Protection Agency, April 29 and May 1, 2019.
66
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may be lessened by the reduced palatability, but risk to consumers of seeds, nuts, arthropods,
and possibly fruits, are not expected to be affected by the desiccating action.
restriall Invertebrate Risk Assessment
rireslirial Invertebrate Exposure Assessment
Terrestrial invertebrate framework assumes honey bees are a surrogate for all terrestrial
invertebrates (USEPA et a!., 2014). The list of crops to which paraquat is applied is summarized
in Table 10-1 (USDA, 2017) along with the USDA pollinator attractive data to identify which
crops may have exposure to pollinators on the field. Off-field assessments are conducted for
foliar sprays regardless of whether the crop is attractive or not (also see Appendix F for more
information). Bees may be exposed on and off the field to a wide range of crops. Not all
registered uses were included in the database in the form they are listed in the use table (Table
3-1) and some notations are made in Table 10-1, but the conclusion is that multiple uses have
the potential to attract pollinators. Because paraquat is used as a desiccant, the likelihood that
it would be applied directly to crops during blooming periods seems low for most crops, but it is
not unfathomable. For example, paraquat might be applied between rows of blooming fruit
trees, which, though not directly on the crops, might be in close proximity.
Table 10-1. Summary of Information on the Attractiveness of Registered Use Patterns for
Paraquat to Bees
Crop Name
Honey Bee Attractive?1'2
Bumble Bee Attractive? 2
Solitary Bee Attractive? ^ 2
Sunflower
Y (pollen2 & nectar2)
Yes2
Yes2
Apricot
Y (pollen2 & nectar2)
Yes2
Yes1
Beans, Dried-Type
Legume Vegetables
Peanuts
Cabbages and Other Brassica
Y (pollen2 & nectar2)
Yes1
Yesi or 2
Vegetables
Turnips and Tyfon
Citrus
Clover
Acerola, Mazzard, Sweet Cherries
Y (pollen2 & nectar1)
Yesi or 2
Yesi o'- 2
Almond
Apple
Alfalfa
Y (pollen1 & nectar2)
Yes1
Yes2
Bushberries
Y (pollen1 & nectar1)
Yes2
Yes1
Caneberries
Artichoke
Y (pollen1 & nectar1)
Yes1
Yes1
Carrot
Clary
Cucurbit Vegetables
Garlic
Guar
67
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Crop Name
Honey Bee Attractive?1'2
Bumble Bee Attractive?2
Solitary Bee Attractive? h 2
Kiwi Fruit
Lentils
Lettuce
Melons
Okra
Peaches/ Nectarines
Pear
Peas
Persimmon
Plums/Prunes
Soybeans
Strawberry
Onion
Y (pollen1 & nectar1)
No or Unknown
Yes1 or Unknown
Asparagus
Avocado
Saff lower
Macadamia Nut
Corn
Y (pollen1)
Yes1 ^
Yes1
Tobacco
Pepper
Coffee
Y (pollen1)
Unknown
Yes1
Sorghum
Grapes
Y (pollen1)
No or Unknown
No or Unknown
Grass/Turf
Hops
Olives
Cotton
Y (nectar1)
Yes1
Yes1
Banana
Y (nectar1)
No
No
Potato, Yams, and Taro
N
Yes1
Yes1 or Unknown
Tomato
Sugar Beet
Eggplant
N
Yes2
Yes1
Barley
N
No
No
Fig
Manioc (Cassava)
Pistachio
Rhubarb
Rice
Sugarcane
Wheat
Cocoa
Not Available, Grouping
Not Available, Grouping not
Not Available, Grouping not
Coniferous/Evergreen/Softwood
not in Database, or
in Database, or Uncertainty
in Database, or Uncertainty
(Non-Food)
Uncertainty
Deciduous/Broadleaf/Hardwood
(Non-Food)
Fallow Land
Flowering Plants
Fruiting Vegetables
Guava
Leafy Vegetables
Mint
Papaya
Passion Fruit
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Crop Name
Honey Bee Attractive?1'2
Bumble Bee Attractive?2
Solitary Bee Attractive? h 2
Pastureland/Rangeland
Pineapple
Premises/Areas
Root and Tuber Vegetables
Subtropical/Tropical Fruit
Tree Nuts
Trees (Non-Food)
Tuberous and Corm Vegetables
Vegetables (Unspecified)
Ginger
Sage
1 Use pattern is opportunistically attractive to bees.
2 Use pattern is attractive in all cases.
10.2 Tier I Exposure Estimates
Contact and dietary exposure are estimated separately using different approaches specific for
different application methods. The Bee-REX model (Version 1.0) calculates default EECs for
contact and dietary routes of exposure for foliar and soil treatment applications.
In cases where the Tier I RQs exceed the level of concern (LOC, discussed below), estimates of
exposure may be refined using measured pesticide concentrations in pollen and nectar of
treated crops, and further calculated for other castes of bees using their food consumption
rates as summarized in the White Paper to support the Scientific Advisory Panel (SAP) on the
pollinator risk assessment process (USEPA, 2012d).
10.3 Terrestrial Invertebrate Risk Characterization (Tier I)
Toxicity endpoints are currently only available for adult acute contact and oral exposures. These
acute endpoints (LD50 of 52 and 22 |ag cation/bee, respectively for contact and oral exposures)
are considered practically non-toxic. Therefore, the following section will briefly describe the
potential for risk to pollinators that could be evaluated using available data; however, chronic
toxicity data for adults and toxicity data for larvae were not available.
10.3.1 Tier I Risk Estimation (Contact Exposure)
On-Field Risk
Since the exposure potential for bees has been identified for multiple crops both on and off the
treated field, the next step in the risk assessment process is to conduct a Tier 1 risk assessment.
By design, the Tier 1 assessment begins with (high-end) estimates of exposure via contact and
oral routes. For contact exposure, only the adult (forager and drones) life stage is considered
69
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since this is the relevant life stage for honey bees. Furthermore, toxicity protocols have only
been developed for acute exposures. Effects are defined by laboratory exposures to groups of
individual bees.
Based on acute contact toxicity, the highest maximum application rate (1.5 lb cation/A for
alfalfa and clover) did not exceed the LOC (0.4) for pollinators (Table 10-2, also see Appendix
D).
Table 10-2. Default Tier 1 Adult, Acute Contact Risk for Honey Bees Foraging on Paraquat-
Treated P
ants
Use
Pattern
Bee
Attractiveness
Max. Single
Application Rate
Dose[ng
cation/bee
per 1 lb cation/A)1
Paraquat Contact
Dose [n g cation/bee)
Acute RQ2
Alfalfa and
Clover
Y (pollen &
nectar)
Attractive in all
cases, except for
alfalfa pollen
which has is
opportunistically
attractive
1.5 lb cation/A
4.1
(165 mg cation/kg)
52
0.08
No values are bolded; Bolded RQ value exceeds (or potentially exceeds) the acute risk LOC of 0.4. No exceedances.
1 Source: USEPA 2014. Guidance for Assessing Pesticide Risks to Bees
2 Based on a 48-h acute contact LDso of 52ng cation/bee for paraquat (MRID 43942603).
10.3.2 Tier I Risk Estimation (Oral Exposure)
On-Field Risk
For oral exposure, the Tier 1 assessment considers just the caste of bees with the greatest oral
exposure (foraging adults). If risks are identified, then other factors are considered for refining
the Tier 1 risk estimates. These factors include other castes of bees and available information
on residues in pollen and nectar which is deemed applicable to the crops of interest.
Based on acute oral toxicity, six out of eight castes of adult bees had LOC exceedances at the
highest single application rate (1.5 lb cation/A) for alfalfa and clover (Table 10-3, also see
Appendix D). For the highest and lowest single application rates (1.01 and 0.5 lb cation/A,
respectively) for all other uses (a few had rates between these highest and lowest rates), two
castes had LOC exceedances, workers foraging for nectar and drones. Worker nurse bees
tending brood and queen also had LOC exceedance with the higher rate (1.01 lb cation/A).
70
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Table 10-3. Tier 1 (Default) Oral Risk Quotients for Adult Nectar Forager and Worker Honey
Bees
Use Pattern
Max. Single
Appl. Rate
Bee Caste/Task
Unit Dose
[fig a.i./bee
perl Iba.i./A)1
Oral Dose
[fig a.i./bee)
Acute Oral
RQ2'34
Alfalfa and
Clover
1.5 lb
cation/A
Worker (cell cleaning and
capping)
4.1
11.0
0.50
Worker (brood and queen
tending, nurse bees)
25
1.1
Worker (comb building,
cleaning and food handling)
10
0.46
Worker (foraging for pollen)
7.2
0.33
Worker (foraging for nectar)
48
2.2
Worker (maintenance of hive
in winter)
5.1
0.23
Drone
39
1.8
Queen (laying 1500 eggs/day)
0.87
0.04
Worker (cell cleaning and
capping)
11
0.50
Multiple
Uses-
Highest
Single
Application
Rate
1.01 lb
cation/A
Worker (cell cleaning and
capping)
2.7
7.4
0.34
Worker (brood and queen
tending, nurse bees)
17
0.76
Worker (comb building,
cleaning and food
handling)
6.9
0.31
Worker (foraging for
pollen)
4.8
0.22
Worker (foraging for
nectar)
32
1.5
Worker (maintenance of
hive in winter)
3.4
0.16
Drone
26
1.2
Queen (laying 1500
eggs/day)
0.58
0.027
Multiple
Uses-
Lower Rate
0.5 lb
cation/A
Worker (cell cleaning and
capping)
1.4
3.7
0.17
Worker (brood and queen
tending, nurse bees)
8.2
0.37
Worker (comb building,
cleaning and food
handling)
3.4
0.15
Worker (foraging for
pollen)
2.4
0.11
Worker (foraging for
nectar)
16
0.73
Worker (maintenance of
1.7
0.078
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Use Pattern
Max. Single
Appl. Rate
Bee Caste/Task
Unit Dose
[fig a.i./bee
perl Iba.i./A)1
Oral Dose
[fig a.i./bee)
Acute Oral
RQ234
hive in winter)
Drone
13
0.59
Queen (laying 1500
eggs/day)
0.29
0.013
1 Source: USEPA 2014. Guidance for Assessing Pesticide Risks to Bees.
2 Based on a 48-h acute oral LDso of 22 ng cation/bee for adults (MRID 43942603).
3 Bolded RQ value exceeds (or potentially exceeds) the acute risk LOC of 0.4 or chronic LOC of 1.0
4 Information on chronic effects not available.
As mentioned in Section 10.1, although multiple crops for which paraquat is registered are
attractive to pollinators, the use pattern does not suggest that paraquat would be applied
directly to crops in blooming phase. Paraquat is used primarily as a burn down product before
crops are planted in the spring (corn, cotton, soybeans, peanuts, etc.). Small winter and spring
annual weeds (broadleaf and grass species) could be present and flowering when those
applications are made and would be targeted by the paraquat application. If sprayed, those
plants and their flowers would likely show symptoms within a few hours and be dead within 1
to 3 days. Paraquat is also used as a desiccant just prior to harvest on crops like potato to get
rid of the vines. In those cases, there may be some large flowering plants in the field where
pollinator exposure could occur. If the plant is large enough, some flowers might escape direct
contact with paraquat and survive for a few more days until the whole plant wilts and dies. In
that case, pollinators would not be expected to be exposed (BEAD, personal communication6).
If applied between rows while crops are blooming, however, this would potentially be a route
of exposure for pollinators.
Off-Field Risk
In addition to bees foraging on the treated field, bees may also be foraging in fields adjacent to
the treated fields. AgDrift analysis showed that distances needed to remove the presumption of
risk for the bee caste at highest risk (workers foraging for nectar) were:
• 4 to 46 feet for the highest application rate (1.5 lb cation/A) for alfalfa and clover;
• 4 to 20 feet at the highest application rate for most uses (1.01 lb cation/A); and
• <1 to 7 feet at the lowest application rate for most uses (0.5 lb cation/A).
6 Personal communication between Bill Chism, Senior Biologist, Biological and Economic Analysis Division and
Marianne Mannix, Chemical Review Manager, Pesticide Re-registration Division, Office of Pesticide Programs, U.S.
Environmental Protection Agency, April 29 and May 1, 2019.
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Coarse droplet size (and low boom for ground applications) roughly halved the distance
applying to fine droplets (and high boom) and similarly, aerial applications of the highest
application rates required approximately twice the distance. As a clarification, even though
BeeRex calculated LOC exceedance at the lower rate (0.5 lb cation/A), the aerial calculations
from the AgDrift model were slightly different and were already below the fraction to remove
the presumption of risk at the edge of the field (Table 10-4, also see Appendix D).
Table 10-4. AgDrift Tier 1 Distances to Remove the Presumption of Oral Risk to Adult Nectar
Forager and Worker Honey Bees
Use, Single Application
Rate
Fraction of
Application
Rate That
Would
Remove the
Presumption
of Risk1
For Aerial Application:
Estimated Distance from Edge of
Field to Approximate Fraction, feet
For Ground Application:
Estimated Distance from Edge of
Field, feet
Fine Droplet
Size2
Coarse Droplet
Size3
Fine Droplet
Size2 / High
Boom
Coarse Droplet
Size3 / Low Boom
Based on Worker Foraging for Nectar
Alfalfa and Clover, 1.5 lb
cation/A
0.18
46
20
17
4
Multiple Uses, 1.01 lb cation/A
0.27
20
14
10
4
Multiple Uses, 0.5 lb cation/A
0.55
<1
<1
7
4
1This is the fraction of the highest calculated caste RQfrom BeeRex (Table 10-3) that would equal the LOC of 0.4
for pollinators.
2Based on a tier 1 aerial-spray and ground-spray scenarios with high boom application (for ground), ASAE very fine
to fine drop spectrum (fine to medium for aerial/fine to very fine for ground) and 90th percentile exposure.
3 Based on a tier 1 aerial-spray and ground-spray scenarios with low boom application (for ground), ASAE
medium/coarse drop spectrum (course to very coarse for aerial/fine to medium/coarse for ground) and 90th
percentile exposure.
10.4 Terrestrial Invertebrate Risk Characterization - Additional Lines of Evidence
Some risk to bees was found based on oral toxicity data, but not on contact data. The oral risk
applied to six out of eight castes of adult bees at the highest single application rate (1.5 lb
cation/A) for alfalfa and clover. At the lowest application rate applying to many uses (0.5 lb
cation/A), only two castes were found to be at risk: drones and workers foraging for nectar.
However, the exposure pathway for nectar is not clear because paraquat is not systemic, but
locosystemic. Nonetheless, based on modeling estimates, distances of up to 46 feet, lower
application rates, coarse droplets, ground vs. aerial, and low boom for ground applications all
were effective in removing the presumption of risk for the caste with the highest RQs.
An additional consideration is that paraquat is often used as a preplant (site preparation)
treatment, rather than a direct foliar spray. For paraquat applied directly to soil, crop
attractiveness would not be a factor in bee exposure. However, if target plants are sprayed
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while flowering or if blooming plants are adjacent to the treated area, spray drift may expose
foraging bees. Exposure to bees depends heavily on timing of application and proximity to
blooming plants.
One bee incident (1029512-0004) involved damage to two bee hives and was of possible
causality but of undetermined legality. This incident suggests potential for harm to pollinators.
Additionally, as mentioned above, many of the ONT aggregate incidents in
Table 6-4 are likely bee incidents. The scarcity of reported incidents should not be construed as
the absence of incidents. Incident reports for non-target animals typically provide information
only on mortality events. Sublethal effects in organisms such as abnormal behavior, reduced
growth and/or impaired reproduction are rarely reported.
With the locosystemic nature of paraquat, the potential may exist for its presence in parts of
plants that may be consumed. Due to rapid plant death, it seems unlikely that it would be taken
up by the target plant and transported to pollen; it would more likely only be available in off-
field non-target plants or pollen as a result of spray drift. Due to its longevity, potential for
paraquat presence in pollen and honey may be a concern. The Tier 1 analysis showed concern
for adults based on acute oral toxicity to some castes of bees, and those risks could be reduced
to below the levels of concern. Risk to larvae and chronic risk to adult bees were not
determined due to lack of data.
Because paraquat is a desiccant and not likely applied directly to blooming crops, pollinator
exposure is likely greater off-field than on-field. However, if paraquat is applied between rows
of blooming crops, then on-field exposure may also be likely.
restrial Plant Risk Assessment
rrestrial Plant Exposure Assessment
EECs for terrestrial plants are calculated using TERRPLANT v.1.2.2. Exposure is estimated for a
single application evaluating exposure via spray drift. Runoff was not considered due to fate
characteristics previously discussed. For spray drift, exposure is estimated approximately 200
feet from the edge of the treated field. Exposures from spray drift are then compared to
measures of survival and growth (e.g., effects to vegetative vigor) to develop RQ values.
Resulting upper bound exposure estimates are in Table 11-1 (also see Appendix D). EECs are
based on the maximum single application rate for terrestrial uses and spray drift fraction. The
EECs represent residues from off-site exposure via spray drift to non-target plants found near
application sites.
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Table 11-1. TerrPlant Calculated EECsfor Terrestrial and Semi-Aquatic Plants near Paraquat
Terrestrial Use Areas
Use Site
Single Max.
Application
Rate
(lb
cation/A)
EECs (lb a.i./A)1
Ground2
Spray Drift
Aerial3
Spray Drift
Alfalfa and Clover
1.5
0.015
0.075
Multiple Ag and Non-Ag
Uses - High Rate
1.01
0.0101
0.0505
Multiple Ag and Non-Ag
Uses - Low Rate
0.50
0.0050
0.025
1 Based on a solubility limit of 336,000 mg cation/L (464,000 mg paraquat dichloride/L * 0.724294 = 336,000; MRID 46098802).
2 Based on a drift fraction of 1% (i.e., 0.01).
3 Based on a drift fraction of 5% (i.e., 0.05).
11.2 Terrestrial Plant Risk Characterization
Monocots and dicots are similarly sensitive to paraquat toxicity. The seedling emergence
endpoints (EC25) used to calculate non-listed species risk, were based on 25% reductions in oat
and cocklebur survival and emergence (Table 6-2 and Appendix B). Oats also had significant
(p<0.05) 21% reduction in survival and emergence at 0.57 lb cation/A, just below the EC25 of
0.64 lb cation/A; although the NOAEL/LOAEL endpoints were not used in these calculations
(they typically are only used for the listed-species calculations which were not done here), they
provide support of effects at this exposure level. Similarly, the cocklebur had measured 21%
reduction in emergence at 0.34 lb cation/A, compared to the calculated EC25 of 0.67, which was
based on emergence data. The vegetative vigor endpoints used in the spray drift calculations
were more sensitive than the seedling emergence endpoints. This is consistent with the mode
of action where paraquat is expected to be absorbed into plant tissue and cause rapid damage,
resulting in more localized effects than systemic uptake. Exposure in the vegetative vigor study
was from direct spray to green parts of the plant, while exposure in the seedling emergence
study was from treated soil.
These EC25S of 0.021 and 0.022 lb cation/A for ryegrass and soybeans were based on 25%
effects in growth (dry weight and height). Ryegrass also had significant (p<0.05) 60% reduction
in dry weight at 0.033 lb cation/A, and soybeans had significant (p<0.05) 20% reduction in
height at 0.018 lb cation/A, which were close to the EC25 estimates, and provide support that
effects may be seen at these exposure levels.
Based on these endpoints and the EECs calculated using TerrPlant (Table 11-1), the LOCs are
exceeded for non-target plants exposed to spray drift (based on vegetative vigor endpoints as
75
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described above) had exceedances for all application rates from aerial spray (RQs from 1.2-3.6)
but not from ground spray (Table 11-2). Distances to remove the presumption of risk range
from <1 foot to 17 feet, depending in part on droplet size.
Table 11-2. Terrestrial Plant Risk Quotients and AdDrift Distances to Remove the Presumption
of Risk
Type of Plant
Ground spray RQs
from Spray Drift1
Aerial Spray RQs
from Spray Drift
RQ/ Fraction of
Applied to Remove
Presumption of Risk
Distance to Fraction of Applied
Fine to Medium
Droplets
Coarse Droplets
Alfalfa and Clover (1.5 lb cation/A)
Monocot
0.72
3.61/0.277
17
14
Dicot
0.69
3.46/0.289
17
10
Multiple Ag and Non-Ag Uses - High Rate (1.01 lb cation/A)
Monocot
0.49
2.43/0.412
7
7
Dicot
0.47
2.33/0.429
7
4
Multiple Ag and Non-Ag Uses - Low Rate
0.5 lb cation/A)
Monocot
0.24
1.20/0.833
<1!
<1!
Dicot
0.23
1.15/0.870
Kl1
Kl1
Bolded RQ values exceed the LOC of 1.0.
1Even though this is a herbicide, the TerrPlant estimate is for the edge of the field so that for ground application,
the model estimates 1% drift and for aerial application 5% drift. As a result, the ground spray RQs are below the
LOC. Similarly, for AgDrift, the model estimates that some of the distances to remove the presumption of risk are
<1 foot.
Twenty-seven plant incidents were found, with paraquat as probable or highly probable cause
in ten; of these, one was from a registered use (1013884-038) involved damage to ornamental
plants from paraquat use on peas. Four additional plant incidents attributed to registered uses
of paraquat on peanuts, pastureland, and non-specified uses were determined to be possibly
caused by paraquat (1011838-005, 1012684-010, 1013636-029, and 1014034-009); these involved
damage to peanut, peppermint and pasture grass in areas ranging from 5 to 181 acres,
suggesting potential for harm to plants from registered use. Fifteen incidents of undetermined
legality were reported, involving damage to corn, peanuts, apples, radishes, winter wheat,
blueberries, alfalfa, onions, non-specified vegetables and ornamentals; of these, four were
determined to have probable causality and eleven to have possible causality for paraquat.
These incidents support the suggestion that a potential for harm to plants is established from
registered use of paraquat.
Therefore, based on the available data, plants exposed to spray drift from aerial applications
are at risk at all registered application rates, which is consistent with paraquat being an
herbicide. Given paraquat's registrations as an herbicide along with many plant damage
76
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incidents linked to paraquat use, plants in areas exposed to paraquat application are expected
to be at risk.
iclusions
Given the uses of paraquat and the chemical's environmental fate properties, there is a
likelihood of exposure of paraquat residues of concern to non-target terrestrial and/or aquatic
organisms. When used in accordance with the label, such exposure may result in adverse
effects upon the survival, growth, and reproduction of non-target terrestrial and aquatic
organisms. Consistent with previous risk assessments (USEPA, 2011a, USEPA, 2014a), all
registered uses of paraquat pose a potential for direct adverse effects to birds, mammals,
terrestrial-phase amphibians, reptiles, terrestrial plants, and aquatic plants, and to a lesser
degree, to pollinators, fish, and benthic invertebrates. Application timing may be important in
preventing reproduction effects to terrestrial vertebrates and also to avoid pollinator effects if
applied onto or near blooming plants. Paraquat is very persistent in the environment. A more
in-depth summary of the risk conclusions is available in the Executive Summary Section 1.
13 Literal
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80
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55088 Knight, B.A.G.; Tomlinson, T.E. (1967) The interaction of Paraquat (1:1'-
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55089 Tomlinson, T.E.; Knight, B.A.G.; Bastow, A.W.; et al. (1968) Structural factors
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55093 Coats, G.E.; Funderburk, H.H., Jr.; Lawrence, J.H.; et al. (1964) Persistence of
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55097 Austin, W.G.L.; Calderbank, A. (1964) Diquat and Paraquat: Residues in Water
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56053 Tucker, B.V. (19??) Lack of Effect of a Polar Hydroxy triazine Com- pound on
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65609 Gamar, Y.; Mustafa, M.A. (1975) Adsorption and desorption of di- quatA2tl and
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65611 Hayes, M.H.B.; Pick, M.E.; Toms, B.A. (1972) Application of micro- calorimetry
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65613 Khan, S.U. (1974) Adsorption of bipyridylium herbicides by humic acid. Journal
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65614 Khan, S.U. (1973) Interaction of bipyridylium herbicides with or- gano-clay
complex. Journal of Soil Science 24(2):244-248. (Also In unpublished submission
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65615 Philen, O.D., Jr.; Weed, S.B.; Weber, J.B. (1970) Estimation of surface charge
density of mica and vermiculite by competitive adsorption of Diquat2+ vs.
Paraquat2+. Soil Science Society of America Proceedings 34:527-531. (Also In
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65618 Tucker, B.V.; Pack, D.E.; Ospenson, J.N. (1967) Adsorption of bipyridylium
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65619 Weber, J.B.; Weed, S.B. (1968) Adsorption and desorption of diquat, paraquat,
and prometone by montomorillanitic and kaolinitic clay minerals. Soil Science
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65621 Weber, J.B.; Perry, P.W.; Upchurch, R.P. (1965) The influence of temperature
and time on the adsorption of paraquat, diquat, 2,4-D and prometone by clays,
charcoal, and an anion-exchange resin. Soil Science Society of America
Proceedings 29(6):678- 688. (Also In unpublished submission received Aug 22,
1977 under 239-1663; submitted by Chevron Chemical Co., Richmond, Calif.;
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65622 Weed, S.B.; Weber, J.B. (1969) The effect of cation exchange capacity on the
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Adsorption and release. Soil Science Society of America Proceedings 33(3):379-
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65623 Weed, S.B.; Weber, J.B. (1968) The effect of adsorbent charge on the
competitive adsorption of divalent organic cations by layer- silicate minerals.
American Mineralogist 53(Mar-Apr):478-490. (Also In unpublished submission
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Richmond, Calif.; CDL: 231430-X)
65624 Best, J.A.; Weber, J.B.; Weed, S.B. (1972) Competitive adsorption of Diquat®,
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68226 Coats, G.E.; Funderburk, H.H., Jr.; Lawrence, J.M.; et al. (1964) Persistence of
diquat and paraquat in pools and ponds. Proceedings of the Southern Weed
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70873 Pack, D.E. (1980) Paraquat, Atrazine and Terbutryn—Dissipation in Soils Alone
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82259 Spinks, C.A.; Hendley, P.; Arnold, D.J. (1976) PP796~Degradation in Soil under
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90396 California Chemical Company (1964) Paraquat Residues in Soil. (Compilation;
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91369 Chevron Chemical Company (19??) The Fate of Paraquat in Soils. (Unpublished
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96972 Pack, D.E. (1977) Soil Mobility of Captan, Folpet and Captafol As Determined by
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111528 McCall, H.; Bovey, R.; McCully, M; et al. (1972) Adsorption and desorption of
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113707 Clinch, R.; Middleton, M.; Winchester, J. (1962) Bipyridylium Herbicides:
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Paraquat in Pools and Ponds. (Unpublished study received Dec 21, 1982 under
239-2247; prepared by Auburn Univ., Agricultural Experiment Station,
submitted by Chevron Chemical Co., Richmond, CA; CDL:249104-I)
Chevron Chemical Co. (1970) Diquat: Residue Tolerance Petition: The Results of
Tests on the Amount of Residue Remaining, Including a Description of the
Analytical Methods Used: Water, Aquatic Life and Soil |. (Compilation;
unpublished study received Dec 12, 1970 under 1F1101; CDL:090861-A)
164-5 Long term soil dissipation
MRID
Citation Reference
146803 Abell, J. (1984) High Rate Paraquat Soil Residue Trial: Mt. Holly New Jersey.
Unpublished study prepared by Chevron Chemical Company. 12 p.
146804 Abell, J. (1984) High Rate Paraquat Soil Residue Trial: Fresno California.
Unpublished study prepared by Chevron Chemical Company. 13 p.
146805 Riley, D.; Abell, J. (19??) Long Term Fate and Biological Activity of Bound
Paraquat Residues in Soil. Unpublished study prepared byJealotts Hill Research
95
-------
Station and Chevron Chemical Co. 16 p.
42738701 Anderson, L.; Hoag, R.; Anders, C. et al. (1992) Paraquat: Field Soil Dissipation
under In-Use Conditions in the USA During 1987-91 (Visalia, California): Lab
Project Number: PP148BD05: RJ1191B. Unpublished study prepared by ICI
Agrochemicals. 132 p.
42738702 Anderson, L.; Hoag, R.; Anders, C. et al. (1992) Paraquat: Field Soil Dissipation
under In-Use Conditions in the USA During 1987-89 (Leland, Mississippi): Lab
Project Number: PP148BD05: RJ1206B. Unpublished study prepared by ICI
Agrochemicals. 98 p.
42802101 Anderson, L.; Hoag, R.; Safford, J. et al. (1992) Paraquat: Field Soil Dissipation
under In-Use Conditions in the USA During 1987-91 (Champaign, III.): Lab
Project Number: PP148BD05: RJ1187B. Unpublished study prepared by ICI
Agrochemicals, Jealott's Hill. 127 p.
42802102 Anderson, L.; Hoag, R.; Anders, C. et al. (1992) Paraquat: Field Soil Dissipation
under In-Use Conditions in the USA During 1987-91 (Goldsboro, NC): Lab
Project Number: PP148BD05: RJ1146B. Unpublished study prepared by ICI
Agrochemicals, Jealott's Hill. 116 p.
PC Codes: 061601 and 061602.
850.2100 Avian Single Dose Oral Toxicity
MRID Citation Reference
29001 Fink, R.; Beavers, J.B.; Grimes, J.; et al. (1979) Acute Oral LDI50A~Bobwhite Quail:
Paraquat dichloride Technical Salt (SX-1142): Project No. 162-121. Final Rept.
(Unpublished study received Feb 21, 1980 under 239-2422; prepared by Wildlife
International, Ltd., submitted by Chevron Chemical Co., Rich- mond, Calif.;
CDL:241819-A)
0160000 Hudson, R.; Tucker, R.; Haegele, M. (1984) Handbook of toxicity of pesticides to
wildlife: Second edition. US Fish and Wildlife Service: Resource Publication 153. 91 p.
Mallard study
49349901 Hubbard, P., Martin, K., and Beavers, J. 2014. Paraquat Dichloride — An Acute Oral
96
-------
49378001
Toxicity Study with the Zebra Finch Using a Sequential Testing Procedure. Final
Report. Wildlife International, Easton, MD. Report Number 528-416. Study
sponsored by Syngenta Crop Protection, LLC, Greensboro, NC. Study initiated on
December 30, 2013 and completed on March 20,1998.
Johnson, A. 1998. Paraquat - Acute Oral LD50 to the Mallard Duck. Final Report. Study
performed by Huntingdon Life Sciences Ltd., Cambridgeshire, England. Report
Number ISN399/963860. Study sponsored by Zeneca Agrochemicals, Jealotts Hill
Research Station, Berkshire, England and sponsored by Syngenta Crop Protection,
LLC, Greensboro, North Carolina. Study initiated on December 18, 1996 and
completed on March 20,1998.
850.2200 Avian Dietary Toxicity
MRID Citation Reference
55103 Ives, M. (1965) Report to Imperial Chemical Industries, Limited: Toxicity Studies on
Pheasants and Wild Mallard Ducks: Paraquat Formulation. (Unpublished study
received Apr 7, 1971 under unknown admin, no.; prepared by Industrial Bio-Test
Labora- tories, Inc., submitted by Chevron Chemical Co., Richmond, Calif.;
CDL:180000-S)
90975 Ives, M. (1965) Report to Imperial Chemical Industries Limited: Toxicity Studies on
Pheasants and Wild Mallard Ducks, Paraquat Formulation. (Unpublished study
received May 6,1966 under 6F0483; prepared by Industrial Bio-Test Laboratories,
Inc.; sub- mitted by Chevron Chemical Co., Richmond, Calif.; CDL:090542-W)
00022923 Hill, E.F.; Heath, R.G.; Spann, J.W.; et al. (1975) Lethal Dietary Toxicities of
Environmental Pollutants to Birds: Special Scientific Report-Wildlife No. 191.
Mallard, Japanese quail, Ring-necked pheasant, and bobwhite quail
850.2300 Avian Reproduction
MRID Citation Reference
110454 Fink, R.; Beavers, J.; Joiner, G.; et al. (1982) One-generation Reproduction—Bobwhite
Quail: Paraquat Technical (SX-1305): Project No. 162-142. Final rept. (Unpublished
study received Aug 18, 1982 under 239-2186; prepared by Wildlife International Ltd.,
submitted by Chevron Chemical Co., Richmond, CA; CDL: 248133-C) LOEC=215 PPM
110455 Fink, R.; Beavers, J.; Joiner, G.; et al. (1982) One-generation Reproduction—Mallard
97
-------
Duck: Paraquat Technical (SX-1305): Project No. 162-145. Final rept. (Unpublished
study received Aug 18, 1982 under 239-2186; prepared by Wildlife International Ltd.,
submitted by Chevron Chemical Co., Richmond, CA; CDL: 248133-D) LOEC= 100 PPM
43942604 Hakin, B.; Chanter, D. (1988) The Effect of Paraquat on the Hatchability of Fertile
Mallard Duck Eggs: Lab Project Number: ISN 170/881711: ISN/170. Unpublished
study prepared by Huntingdon Research Centre, Ltd. 128 p.
43942605 Roberts, N.; Hakin, B.; Chanter, D. (1989) The Effect of Paraquat on the Hatchability
of Fertile Pheasant Eggs: Amended Report: Lab Project Number: ISN 171/881712:
ISN/171. Unpublished study prepared by Huntingdon Research Centre, Ltd. 134 p.
00025808 Dunachie, J.F.; Fletcher, W.W. (1967) Effect of some herbicides on the hatching rate
of hen's eggs. Nature 215(?/Sep):1406-1407. (Also~ln~unpublished submission
received Jan 2, 1980 under 2217- 485; submitted by PBI-Gordon Corp., Kansas City,
Kans.; CDL: 241581-K)
00055110 Fletcher, K. (1967) Production and Viability of eggs from hens treated with Paraquat.
Nature 215(Sep 23):1407-1408. (Also~ln~ unpublished submission received Apr 7,
1971 under unknown admin, no.; submitted by Chevron Chemical Co., Richmond,
Calif.; CDL: 180000-AC)
110453 Fink, R.; Beavers, J.; Joiner, G.; et al. (1981) Subacute Feeding- Reproduction
Screening Bioassay (Bobwhite Quail): Paraquat Technical (SX-1305): Project No. 162-
138; S-1994. Final rept. (Unpublished study received Aug 18,1982 under 239-2186;
pre- pared by Wildlife International Ltd., submitted by Chevron Chemical Co.,
Richmond, CA; CDL:248133-B)
110452 Leary, J.; Tucker, B. (1981) Assessment of Diet Homogeneity and Stability of Paraquat
Technical (SX-1305) in Game Bird Ration (Wildlife International Ltd. Project 162-136):
Chevron File No. 721.il/S-1951. (Unpublished study received Aug 18, 1982 under
239-2186; submitted by Chevron Chemical Co., Richmond, CA; CDL:248133-A)
850.1075 Acute Toxicity to Freshwater Fish
MRID Citation Reference
31860 Beasley, P. (1965) Effects of Diquat and Paraquat on Channel Cat- fish Eggs and Fry.
(Unpublished study received Sep 15, 1972 un- der 1F1101; prepared by Auburn
Univ., Fisheries Dept., submitted by Chevron Chemical Co., Richmond, Calif.;
CDL:090862-AJ)
113705 McCann, J. (1969) Ortho Paraquat CL: Bluegill |. (U.S. Agricul- tural Research Service,
98
-------
Animal Biology Laboratory; unpublished study; CDL:103609-A)
118540 Lawrence, J. (1962) Observed Fish Mortality in Plastic Pools Treated with Herbicides
during 1962. (Unpublished study received Jul 7,1972 under 2F1213; prepared by
Auburn Univ., Agr. Exp. Station, submitted by Amchem Products, Inc., Ambler, PA;
CDL: 091039-1)
129075 Lorz, H.; Glenn, S.; Williams, R.; et al. (1979) Effects of Selected Herbicides on
Smolting of Coho Salmon. By Oregon, Dept. of Fish and Wildlife, Research and
Development Section and U.S. Forest Service, Pacific Northwest Forest and Range
Experiment Station. Corvallis, OR: US EPA. (EPA-600/3-79-071; Grant #R- 804283;
pages i,iv-x,1,6-14,40-50,83-85,92 only; also In unpublished submission received Jun
24,1983 under 464-502; submitted by Dow Chemical U.S.A., Midland, Ml;
CDL:250605-N)
134846 Calmbacher, C. (1978) The Acute Toxicity of Banvel 4 + Aatrex 80WP + Princip WP +
Paraquat 2EC to the Bluegill Sunfish ...: UCES Proj. No. 11506-03-38. (Unpublished
study received 1978 under 876-EX-33; prepared by Union Carbide Corp., submitted
by Velsicol Chemical Corp., Chicago, IL; CDL:234452-B)
140031 Funderburk, H.H. (1963) Distribution of C14 Labeled Herbicides in Bluegillsand
Shellcrackers. Annual rept. 1963. (Unpublished study received Apr 19, 1968 under
264-EX-30G; prepared by Auburn Univ., Dept. of Botany and Plant Pathology,
submitted by Union Carbide Agricultural Products Co., Inc., Ambler, Pa.; CDL:
123220-D)
139543 or Johnson, W.; Finley, M. (1980) Handbook of Acute Toxicity of Chemi- cals to Fish
40094602 and Aquatic Invertebrates. Washington, DC: U.S. Fish and Wildlife Service.
(Resource publication 137; also In unpublished submission received Dec 15, 1983
under 239-2460; submitted by Chevron Chemical Co., Richmond, CA; CDL:252083-
B)
162736 Palmateer, S. (1980) Biological Report of Analysis: [Toxicity Test of Paraquat on
Rainbow Trout]. Unpublished study prepared by U.S. Environmental Protection
Agency, Terrestrial & Aquatic Biology Laboratory. 1 p.
162737 Palmateer, S. (1979) Biological Report of Analysis: [Toxicity Test of Paraquat on
Bluegills]. Unpublished study prepared by U.S. Environmental Protection Agency,
Terrestrial & Aquatic Biology Laboratory. 1 p.
162738 McCann, J. (1977) Biological Report of Analysis: [Toxicity Test of Ortho Paraquat CL
Concentrate on Rainbow trout]. Unpublished study prepared by U.S. Environmental
Protection Agency, Animal Biology Laboratory. 1 p.
99
-------
40098001 Mayer, F.; Ellersieck, M. (1986) Manual of Acute Toxicity: Inter- pretation and Data
Base for 410 Chemicals and 66 Species of Freshwater Animals. US Fish & Wildlife
Service, Resource Pub- lication 160. 579 p.
Rainbow trout, channel cat, bluegill,
850.1010 Acute Toxicity to Freshwater Invertebrates
MRID Citation Reference
113694 Sanders, H.; Cope, O. (1966) Toxicities of several pesticides to two species of
cladocerans. Trans. Amer. Fish Soc. 95:165-169. (Also In unpublished submission
received Jun 13, 1979 under 239-2186; submitted by Chevron Chemical Co.,
Richmond, CA; CDL:098334-B)
114473 Wheeler, R. (1978) 48 Hour Acute Static Toxicity of Paraquat Dichloride Salt (SX957)
to 1st Stage Nymph Water Fleas (Daphnia magna Straus). (Unpublished study
received Sep 15,1978 under 239-2422; submitted by Chevron Chemical Co.,
Richmond, CA; CDL:235419-A)
162752 Tompkins, J. (1979) Biological Report of Analysis: [Toxicity of Ortho Paraquat to
Daphnia magna]. Unpublished study prepared by U.S. Environmental Protection
Agency, Terrestrial & Aquatic Bio- logy Unit Laboratory. 1 p.
40098001 Mayer, F.; Ellersieck, M. (1986) Manual of Acute Toxicity: Inter- pretation and Data
Base for 410 Chemicals and 66 Species of Freshwater Animals. US Fish & Wildlife
Service, Resource Pub- lication 160. 579 p. - Daphnia, stonefly nymph and Gammarus
faciatus
850.1075/850.1025/850.1035 Acute Exposures to Estuarine/Marine Organisms
40228401 Mayer, F.L. USEPA Gulfbreeze Estuarine Toxicity tests - marine algaes, brown
shrimp, oyster, longnose killifish
49320301 Claude, MB, KH Martin, SP Gallagher. (2014) Paraquat Dichloride - A 96-Hour
Shell Deposition Test with the Eastern Oyster (Crassostrea virginica). Study
performed by Wildlife International, Easton, Maryland, USA. Laboratory report ID:
528A-259. Study sponsored by Syngenta Crop Protection, LLC. Greensboro, North
Carolina, USA. Study completed: January 21, 2014.
Claude, MB, KH Martin, SP Gallagher. (2014) Paraquat Dichloride - A 96-Hour
49320302 Flow-Through Acute Toxicity Test with the Saltwater Mysid (Americamysis bahia).
Study performed by Wildlife International, Easton, Maryland, USA. Laboratory
100
-------
report ID: 528A-257. Study sponsored by Syngenta Crop Protection, LLC.
Greensboro, North Carolina, USA. Study completed: January 30, 2014.
Claude, M.B., K.H. Martin, and S.P. Gallagher. 2014. Paraquat Dichloride - A 96-
Hour Flow-Through Acute Toxicity Test with the Fathead Minnow (Pimephales
promelas). Study conducted by Wildlife International, Easton, Maryland, USA.
49320303
Laboratory Project ID: 528A-258. Study sponsored by Syngenta Crop Protection,
LLC, Greensboro, North Carolina, USA. Study initiated on September 3, 2013 and
completed January 23, 2014.
Claude, M.B., K.H. Martin, and S.P. Gallagher. Paraquat Dichloride - A 96-Hour
Flow-Through Toxicity Test with the Sheepshead Minnow (Cyprinodon
variegatus). Study conducted by Wildlife International, Easton, Maryland, USA.
49320304
Laboratory Project ID: 528A-264. Study sponsored by Syngenta Crop Protection,
LLC, Greensboro, North Carolina, USA. Study initiated on September 24, 2013 and
completed January 24, 2014.
850.1300/850.1350/850.1400 Fish Early Life Stage/Aquatic Invertebrate Life Cycle Study
MRID Citation Reference
Austin, W.G.L.; Calderbank, A. (1964) Diquat and Paraquat: Residues in Water and
Toxicity to Fish and Other Aquatic Fauna: Experimental Report No. PP/E/303.
(Unpublished study received Sep 15, 1972 under 1F1101; prepared by Imperial
Chemical Industries, Ltd., submitted by Chevron Chemical Co., Richmond, Calif.;
CDL: 090862-AC)
Silvo, O.E.J. (1967) Alustavia Tutkimuksia Eraiden Herbisidien Myrkyllisyydesta
Nuorille Karpin Poikasille (~Cyprinus carpio~ L~.). N.P. (Suomen Kalatalous 32
Finlands Fiskerier; incom- plete; also~ln~unpublished submission received Jul 11,
1961 un- der 1E1046; submitted by U.S. Dept. of the Army, Washington, D.C.;
CDL:093359-X)
Claude, M.B., K.H. Martin, and S.P. Gallagher. 2014. Paraquat Dichloride - A Flow-
Through Life-Cycle Toxicity Test with the Cladoceran (Daphnia magna).
Unpublished study performed by Wildlife International Easton, Maryland, USA.
Laboratory Study No. 528A-260. Study sponsored by Syngenta Crop Protection,
LLC, Greensboro, North Carolina, USA. Study initiated September 6, 2013 and
completed February 14, 2014.
Claude, M.B., K.H. Martin, S.P. Gallagher, E.S. Bodle, and H.O. Krueger. 2014.
Paraquat Dichloride - A Flow-Through Life-Cycle Toxicity Test with the Saltwater
31853 or
55097
55714
49320305
49320306
101
-------
Mysid (Americamysis bahia). Unpublished study performed by Wildlife
International Easton, Maryland, USA. Laboratory Study No. 528A-261. Study
sponsored by Syngenta Crop Protection, LLC, Greensboro, North Carolina, USA.
Study completed February 14, 2014.
Claude, M. et al. 2014. Paraquat Dichloride: An Early Life-Stage Toxicity Test with
the Fathead Minnow (Pimephales promelas). Unpublished study performed by
49320307 Wildlife International, Easton, Maryland. Laboratory Study No. 528A-262. Study
sponsored by Syngenta Crop Protection, LLC, Greensboro, NC. Study initiated
October 10, 2013 and completed February 14, 2014.
Claude, M. et al. 2014. Paraquat Dichloride-An Early Life-Stage Toxicity Test with
the Sheepshead Minnow (Cyprinodon variegatus). Unpublished study performed
49320308 by Wildlife International, Easton, Maryland, USA. Laboratory Study No. 528A-263.
Study sponsored by Syngenta Crop Protection, LLC, Greensboro, North Carolina,
USA. Study initiated October 29, 2013 and completed February 14, 2014.
850.1735/850.1740/ Non-Guideline Sediment Toxicity Studies
MRID Citation Reference
36935 Atkins, E.L.; Greywood, E.A.; Macdonald, R.L. (1975) Toxicity of Pesticides and
Other Agricultural Chemicals to Honey Bees: Labo- ratory Studies. By University of
California, Dept. of Entomolo- gy. ?: UC, Cooperative Extension. (Leaflet 2287;
published study.)
48877201 Hamer, M.J. 1998. Paraquat - Sediment Toxicity Test with Chironomous riparius.
Study performed by Zeneca Agrochemicals. Laboratory report ID: RJ2649B. Study
sponsored by Syngenta Crop Protection, LLC. Study completed: July 30,1998.
OECD Guideline 218.
48877202 Algal study with dosed sediment; listed under 850.4500.
Bradley, M.J. 2015. 10-Day Toxicity Test Exposing Midge (Chironomus dilutus) to
Paraquat Dichloride Applied to Sediment Under Static-Renewal Conditions
Following OCSPP Draft Guideline 850.1735. Unpublished study performed by
Smithers Viscient, Wareham, MA, USA. Laboratory Study No. 1781.7016. Study
sponsored by Syngenta Crop Protection, LLC, Greensboro, North Carolina, USA.
Study completed February 13, 2015 (Final Report Amendment 1).
49577001
49577002
Bradley, M.J. 2015. 10-Day Toxicity Test Exposing Estuarine Amphipods
(Leptocheirus plumulosus) to Paraquat Dichloride Applied to Sediment under
102
-------
Static Conditions Following OCSPP Draft Guideline 850.1740. Unpublished study
performed by Smithers Viscient, Wareham, MA, USA. Laboratory Study No.
1781.7018. Study sponsored by Syngenta Crop Protection, LLC, Greensboro,
North Carolina, USA. Study completed February 13, 2015.
Bradley, M.J. 2015. 10-Day Toxicity Test Exposing Amphipods (Hya lei la azteca) to
Paraquat Dichloride Applied to Sediment Under Static-Renewal Conditions
49577003 F°"°wing 0CSPP Draft Guideline 850'1735' Unpublished study performed by
Smithers Viscient, Wareham, MA, USA. Laboratory Study No. 1781.7017. Study
sponsored by Syngenta Crop Protection, LLC, Greensboro, North Carolina, USA.
Study completed February 13, 2015.
850.4400 Aquatic plant growth- Vascular Plants
MRID Citation Reference
40165104 Blackburn, R.; Weldon, L. (1965) The Sensitivity of Duckweeds (Le- mnaceae) and
Azolla to Diquat and Paraquat: Laboratory Project ID: #87022-C and #87025-C.
Unpublished study prepared by US Agricultural Research Service, Fort Lauderdale,
Florida. 5 p.
850.4500 Aquatic plant growth- Algae
MRID Citation Reference
42601002 Smyth, D.; Sankey, S.; Penwell, A. (1992) Paraquat Dichloride: Toxicity to the
Green Alga Selenastrum capricornutum: Lab Project Number: BL4578/B: T168/G
(FT11/92). Unpublished study prepared by Imperial Chemical Industries PLC. 23 p.
42601003 Smyth, D.; Sankey, S.; Cornish, S.; et al (1992) Paraquat Dichloride: Toxicity to the
Duckweed Lemna Gibba: Lab Project Number: BL4493/B: T168/E (FT10/92).
Unpublished study prepared by Imperial Chemical Industries PLC. 24 p.
42601004 Smyth, D.; Sankey, S.; Penwell, A. (1992) Paraquat Dichloride: Toxicity to the
Marine Alga Skeletonema costatum: Lab Project Number: BL4580/B: T168/C
(FT08/92). Unpublished study prepared by Imperial Chemical Industries PLC. 22 p.
42601005 Smyth, D.; Sankey, S.; Cornish, S. (1992) Paraquat Dichloride: Toxicity to the Blue-
green Alga Anabaena flos-aquae: Lab Project Number: BL4579/B: T168/B
(FT07/92). Unpublished study prepared by Imperial Chemical Industries PLC. 26 p.
42601006 Smyth, D.; Sankey, S.; Cornish, S. (1992) Paraquat Dichloride: Toxicity to the
Freshwater diatom Navicula pelliculosa: Lab Project Number: BL4464/B: T168/D
(FT09/92). Unpublished study prepared by Imperial Chemical Industries PLC. 22 p.
48877202 Shillabeer, N. 2000. Paraquat Dichloride: Toxicity to the Freshwater diatom
103
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Navicula pelliculosa: Lab Project Number:AG0463B. Brixham Laboratories, Devon
UK. Sponsor-Syngenta.
850.4100 Seed Emergence
42639601 Canning, L. and J.S. White. 1992. Paraquat: A Glasshouse Study to Evaluate the
Effects on Seedling Emergence of a 300 g ai litre 1 (2.5 lb ai US gal"1) Soluble
Concentrate Formulation on Terrestrial Non-target Plants. Laboratory Project ID
No. 92JH089. Conducted by ICI Agrochemicals, Jealotts Hill Research Station,
Bracknell, Berkshire, UK. Submitted by ICI Americas Inc., Wilmington, DE. EPA
MRID No. 426396-01.
49320310 Martin, J. Paraquat Dichloride (A7813Q) - Seedling Emergence Test. Final Report.
Unpublished study performed by Smithers Viscient, Wareham, MA. Study
Number: 1781.6948. Study sponsored by Syngenta Crop Protection, LLC. Study
completed January 23, 2014.
850.4150 Vegetative Vigor
42601001 Canning, L. and J.S. White. 1992. Paraquat: A Glasshouse Study to Evaluate the
Effects on Vegetative Vigour of a 300 g ai litre 1 (2.5 lb ai US gal-1) Soluble
Concentrate Formulation on Terrestrial Non-target Plants. Laboratory Project ID
No. 92JH088. Conducted by ICI Agrochemicals, Jealotts Hill Research Station,
Bracknell, Berkshire, UK. Submitted by ICI Americas, Inc., Wilmington, DE. EPA
MRID No. 426010-01.
49320309 Martin, J.A. Paraquat Dichloride (A7813Q) - Vegetative Vigor Test. Final Report.
Unpublished study performed by Smithers Viscient, Wareham, MA. Project No.:
1781.6947. Study sponsored by Syngenta Crop Protection, LLC. Study completed
January 23, 2014.
850.3020 Honey bee acute contact
MRID Citation Reference
43942603 Bull, J.; Wilkinson, W. (1987) Paraquat: Acute 5-Day Contact and Oral Toxicity to
Honey Bees (Apis mellifera): Lab Project Number: RJ0578B: PP148CM008.
Unpublished study prepared by ICI Plant Protection Division. 27 p.
00036935 Atkins, E.L.; Greywood, E.A.; Macdonald, R.L. (1975) Toxicity of Pesticides and
Other Agricultural Chemicals to Honey Bees: Labo- ratory Studies. By University of
California, Dept. of Entomolo- gy. ?: UC, Cooperative Extension. (Leaflet 2287;
published study.)
00111488 Moffett, J.; Morton, H.; MacDonald, R. (1972) Toxicity of some herbicidal sprays
104
-------
to honey bees. Journal of Economic Entomology 65(l):32-36. (Also In unpublished
submission received Sep 26, 1974 under 464-323; submitted by Dow Chemical
U.S.A., Midland, Ml; CDL:120345-H) - reviewed by A. Vaughan
05001991 Stevenson, J.H. (1978) The acute toxicity of unformulated pesticides to worker
honey bees (?~Apis mellifera~L_). Plant Pathology 27(l):38-40.
Simulated or Actual Field Testing
MRID Citation Reference
23951 Larsen, H.H.; Hartman, R.F.; Cooper, R.F.; et al. (1976) Aquazine A(R)I: As an
Exposed Bottom Treatment for Fish Hatchery, Fish Rearing and Other Ponds with
Draining Capabilities. (Unpub- lished study received Aug 26, 1977 under 100-437;
prepared in cooperation with U.S. Fish and Wildlife Service, National Fish
Hatchery and others, submitted by Ciba-Geigy Corp., Greensboro, N.C.;
CDL:231410-A)
31847 Lawrence, J.M. (1965) Effects of Single and Repeated Applications of Diquat and
Paraquat on Fathead Minnow and Channel Catfish Production in Plastic Pools.
(Unpublished study received Sep 15, 1972 under 1F1101; prepared by Auburn
Univ., Fisheries Dept., submitted by Chevron Chemical Co., Richmond, Calif.; CDL:
090862-U)
111488 Moffett, J.; Morton, H.; MacDonald, R. (1972) Toxicity of some herbicidal sprays
to honey bees. Journal of Economic Entomology 65(l):32-36. (Also In unpublished
submission received Sep 26, 1974 under 464-323; submitted by Dow Chemical
U.S.A., Midland, Ml; CDL:120345-H)
105
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Appendix A. ROCKs table
Table Bl. Chemical Names and Structures of Paraquat and its Transformation Products
Code Name/
Synonym
Chemical Name
Chemical Structure
Study Type
MRID
Maximum
%AR (day)
Final %AR (day)
PARENT
Paraquat Cation
l,l'-dimethyl-4,4'-bipyridinium
CAS No.: 4685-14-7
Formula: C12H14N2
MW: 186.25 g/mol
SMILES:
C[n+]lccc(ccl)c2cc[n+](C)cc2
Hydrolysis - all pH
00148506
100% (30 @ 25°C)
100% (30 @ 40°C)
Aqueous photolysis in
pH 7 buffer
40562301
100% (37)
Soil photolysis
00146807
100% (?)
Aerobic Soil
41319301
93% (180)
Anaerobic Soil
41319302
94.2% (90)
Aerobic Aquatic
00055093
100% (?)
Anaerobic Aquatic
No study
NA
MAJOR (>10%) TRANSFORMATION PRODUCTS
None
MINOR (<10%) TRANSFORMATION PRODUCTS
4-carboxy-l-
methylpyridinium
(RS)-2'-(4,6-
dimethoxypyrimidin-2-
yl)hydroxymethyl-6'-
meth oxy m ethy 1-1,1-
difluoromethanesulfonamide
CAS No.: 221205-90-9
Formula: C16H19F2N306S
MW: 419.40 g/mol
SMILES:
cl(COC)c(NS(=0)(=0)C(F)F)c(C(
0)c2nc(0C)cc(0C)n2)cccl
w <
This compound was
identified in a
literature study as a
minor
photodegradate and
is the subject of a
leaching study (MRID
00114414-B).
Literature
study
NA
NA
Carbon dioxide
Carbon dioxide
O
0
Aerobic Soil
41319301
<0.1% (180)
<0.1% (180)
106
-------
Code Name/
Synonym
Chemical Name
Chemical Structure
Study Type
MRID
Maximum
%AR (day)
Final %AR (day)
Formula: CO2
MW: 44.1 g/mol
SMILES: 0=C=0
Anaerobic Soil
41319302
<0.1% (180)
<0.1% (90)
Aerobic Aquatic
00055093
?
?
Unextracted
residues
(not applicable)
(not applicable)
Aerobic Soil
41319301
4.1% (0)
0.7% (180)
Anaerobic Soil
41319302
4.1% (0)
0.75% (90)
Aerobic Aquatic
00055093
?
?
AR means "applied radioactivity". MW means "molecular weight".
107
-------
Appendix B. Paraquat Toxicity Data
The purpose of this appendix is to update the comprehensive toxicity list to include toxicity studies newly submitted or amended
since the problem formulation (USEPA, 2011; note: references cited in this appendix are listed at the end of the appendix). Several
plant and avian toxicity studies were amended at the time of the problem formulation and those changes already captured in that
document. Since that time, one plant study was amended and additional submitted studies reviewed —newly reviewed studies
include: two aquatic invertebrate acute studies, three benthic invertebrate (sediment toxicity) acute studies, one benthic
invertebrate (sediment toxicity) emergence study, one algal (non-guideline alteration for sediment exposure) study, two aquatic
invertebrate chronic studies, two fish acute studies, two fish early life-stage studies, two avian acute oral studies, three avian
reproduction studies, and two terrestrial plant studies. Data from these studies are included in the following tables (identified as
"NEW") and endpoints that were determined to be the most sensitive/defensible ones for risk calculation are also included in the
body of this document (Table 6-1 and Table 6-2). These studies fulfill the data gaps, with the exception of some pollinator studies,
which were requested after the problem formulation (and possibly a need for chronic sediment toxicity data with the amphipod,
Hya lei la—see note on the chronic midge study below).
The data presented in this appendix are from studies submitted by registrants or from the public literature, identified using ECOTOX
(USEPA, 2007); an ECOTOX run from December, 2008 was checked during for the problem formulation (USEPA, 2011) and the on-
line database rechecked in June, 2018. In the recheck, public literature was searched for studies with more sensitive endpoints, but
none were identified for further review.
As described in the problem formulation (USEPA, 2011, see especially Section 4.3 Environmental Fate and Transport, Degradation
section, and Section 4.5 Nature of Stressor), paraquat dichloride is generally applied as a flowable solution, already dissociated into
its cation, paraquat, and paraquat is stable in the environment, with no major degradates of concern. Although only the paraquat
dichloride form is currently registered (PC code 061601), toxicity data are also considered for paraquat (PC code 061603), and
paraquat bis (methyl sulfate) (PC code 061602). All toxicity values, consistent with the problem formulation and the response to
comments (USEPA, 2012), were converted (as needed) from paraquat dichloride (molecular weight: 257.158 g/mol) to the paraquat
cation (molecular weight: 186.258 g/mol) by using a conversion factor of 0.724294.
108
-------
Toxicity to Aquatic Organisms
A comprehensive list of available toxicity data for aquatic invertebrates and fish is found in Table B-l. A summary of data from most
of the studies is found in the problem formulation (USEPA, 2011) and the red-legged frog assessment (USEPA, 2009); the new data
reviewed since the problem formulation are noted as "NEW" in the MRID/Classification column.
Table B-l. Summary of Aquatic Toxicity Data for Paraquat Expressed as Paraquat Cation.
Species
Tested
Guideline Note
(if Applicable)
Test Substance:
% a.i.
Toxicity Value, mg cation/L
(95% C.I.)
Slope (if applicable)
MRID
(or other Citation)
Classification
NEW Studies Noted
Notes
Freshwater Invertebrates Acute Toxicity 850.1010 (or equivalent §72-2) Unless Noted:
Water Flea
Daphnia
magna
TGAI: (92.3%
paraquat
dichloride) 66.8%
cation
48-hr ECso = 1.3 (1.0-1.5)
Slope: 4.4
00114473
Supplemental
(quantitatively
usable)
Most sensitive/defensible aquatic invertebrate acute endpoint: EC50 =
1.3 mg cation/L based on immobility.
Static test with measured concentrations. The endpoint may be used
quantitatively. Some uncertainty is associated with the EC50 value
because the test did not include any treatment levels where no
mortality was observed (three levels total).
Water Flea
D. magna
Formulation
48-hr ECso = 1.7
162752
Supplemental
Water Flea
D. magna
Formulation:
21.2%
48-hr EC50 = 3.6 (2.7-4.7)
Slope: 4.8
40098001
Supplemental
From collection of Mayer & Ellersieck, 1986.
Water Flea
D. magna
Formulation:
21.2%
48-hr EC50 = 3.8 (2.8-5.2)
Slope: 3.6
40098001
Supplemental
From collection of Mayer & Ellersieck, 1986.
Water Flea
D. magna
Formulation
Paraquat
dichloride (1,1'-
dimethyl-
4,4'bipyridinium
chloride): 29.1%
48-hr EC50 = 8.0 (3.4-18.7) mg
formulation/L (approx. 2.3 mg
cation/L)
00162752
Supplemental
109
-------
Species
Tested
Guideline Note
(if Applicable)
Test Substance:
% a.i.
Toxicity Value, mg cation/L
(95% C.I.)
Slope (if applicable)
MRID
(or other Citation)
Classification
NEW Studies Noted
Notes
Stonefly
Pteronarcys
californica
Formulation:
21.2%
96-hr EC50 >10
40098001
Supplemental
From collection of Mayer & Ellersieck, 1986
Scud
Gammarus
fasciatus
Formulation:
21.2%
96-hr EC50 = 12 (6.2-15)
Slope: 4.1
40098001
Supplemental
From collection of Mayer & Ellersieck, 1986.
Water Flea
Diaphanosom
a excisum
TGAI: (Purity
Unknown)
48-hr (roughly LC50 at the LOAEC)
NOAEC/ LOAEC approximately
0.004/ 0.04 (0.0058/ 0.0577 mg
a.i./L in paper)
E112408
(Leboulanger, et. al.,
2009)
Supplemental
(qualitatively usable)
NEW
Effect was 40-60% mortality in 24-hours and 60-80% mortality at 48-
hours. In the same study, another species, Moina micrura, had a 48-hr
LC50 between 0.04 and 0.40 mg cation/L (0.0577 and 0.577 mg a.i./L
reported), with 100% mortality at 0.40 mg cation/L. Insufficient
information is available from the open literature publication for the
endpoint to be quantitatively usable to calculate risk, but does suggest
that some Crustacea may be more sensitive than the available
quantitatively usable endpoints.
Saltwater Invertebrates Acute Toxicity:
Mysid and Non-Guideline Saltwater Crustacea 850.1035 (or equivalent §72-3C):
Mysid
Americamysis
bahia
TGAI: (46.3%
paraquat
dichloride) 33.5%
cation
96-hr LC50 = 0.228 (0.188-0.277)
Slope: 4.91
49320302
Acceptable
Most sensitive/defensible E/M crustacean acute endpoint: EC50 = 0.228
mg cation/L.
Flow-through study with mean-measured concentrations.
Brown Shrimp
(Penaeus
aztecus)
Formulation
96-hr EC50 >0.72
40228401
Supplemental
This endpoint is from the U.S. EPA Gulfbreeze lab collection and was not
the most sensitive endpoint and, therefore, was not further investigated
to determine if the endpoint is quantitatively usable or to supply further
details.
Oyster Shell Deposition 850.1025:
Eastern Oyster
Crassostrea
virgninica
TGAI: (46.3%
paraquat
dichloride) 33.5%
cation
96-hr EC/ICso = 22.5 (14.0-36.3)
49320301
Acceptable
New
Most sensitive/defensible mollusk acute endpoint: EC/IC50 = 22.5 mg
cation/L.
Flow-through study with mean-measured concentrations.
110
-------
Species
Tested
Guideline Note
(if Applicable)
Test Substance:
% a.i.
Toxicity Value, mg cation/L
(95% C.I.)
Slope (if applicable)
MRID
(or other Citation)
Classification
NEW Studies Noted
Notes
Eastern Oyster
C. virgninica
Formulation
96-hr EC/ICso >0.72
40228401
Supplemental
This endpoint is from the U.S. EPA Gulfbreeze lab collection and was not
the most defensible endpoint (did not appear to be tested at high
enough concentrations for definitive endpoint)) and, therefore, was not
further investigated to determine if the endpoint is quantitatively usable
or to supply further details.
Invertebrate Chronic Toxicity - Life Cycle Test 850.1300/850.1350 (or equivalent §72-4b):
Most sensitive/defensible aquatic invertebrate chronic endpoint:
NOAEC / LOAEC = 0.038/0.076 mg cation/L based on survival and
reproduction.
Flow-through study with mean-measured concentrations. Study
duration was 32 days total (second generation = 96 hours); at least 7
days past the median time of first brood release in controls (Day 19).
Mysid
A bahia
TGAI: (46.3%
paraquat
dichloride) 33.5%
cation
28-day (32-day total) NOAEC/
LOAEC = 0.038/0.076
based on survival and
reproduction
49320306
Acceptable
NEW
The NOAEC/LOAEC of 0.038/0.076 mg cation/L was based on F0 (post-
pairing) survival and Fi survival and on number of offspring/female day.
At 0.076 mg cation/L, F0 and Fi respective survival were significantly
(p<0.05) reduced by 38.4% and 20.5%; also offspring/female were
reduced by 49.7% (also 51.7% reduction in offspring/reproductive day)
and the pattern appeared to be dose:dependent with 100% reduction in
the next higher treatment (only 32% of the adults survived in that
treatment, which was the 0.153 mg cation/L treatment). Even though
this was not statistically significant due to variability, it is deemed
biologically significant. Both mortality and reproduction impairment
measurements strongly support that effects are seen at or near the
LOAEC.
Other Endpoints:
Time to First Brood:
NOAEC: 0.076 mg cation/L
LOAEC: >0.076 mg cation/L
Growth (Dry Weight and Length of both Males and Females):
NOAEC: 0.153 mg cation/L
LOAEC: >0.153 mg cation/L
Ill
-------
Species
Tested
Guideline Note
(if Applicable)
Test Substance:
% a.i.
Toxicity Value, mg cation/L
(95% C.I.)
Slope (if applicable)
MRID
(or other Citation)
Classification
NEW Studies Noted
Notes
Water Flea
D. magna
TGAI: (46.3%
paraquat
dichloride) 33.5%
cation
21-day NOAEC/LOAEC =
0.097/0.20
based on growth
49320305
Acceptable
NEW
Most sensitive/defensible freshwater invertebrate chronic endpoint:
NOAEC / LOAEC = 0.097/0.20 mg cation/L based on growth.
Flow-through study with mean-measured concentrations.
The NOAEC/LOAEC of 0.097/0.20 mg cation/L was based on a significant
(p<0.05) 4% reduction in mean length and a 22% reduction in mean dry
weight that was determined to be biologically significant, although it
was not statistically significant (p<0,05) due to variability. The LOAEC
was supported by a weight of evidence in that although the 4%
reduction in mean total length was a significant (p<0.05) reduction, the
small amount of change might be questionable. The next higher
treatment level (0.40 mg cation/L) had no survival after 21 days, and
significant (p<0.05) 86.5% reduction in mean young/surviving adult,
which strongly supports that effects are seen at or near the LOAEC.
Other Endpoints:
Reproduction:
Mean Neonates Per Reproductive Day:
NOAEC: 0.20 mg cation/L
LOAEC: 0.40 mg cation/L
Cumulative Offspring:
NOAEC: 0.20 mg cation/L
LOAEC: >0.20 mg cation/L
Survival:
21-day LC50 = 0.269 (0.252-0.288): Slope: N/A
NOAEC: 0.20 mg cation/L
LOAEC: 0.40 mg cation/L
112
-------
Species
Tested
Guideline Note
(if Applicable)
Test Substance:
% a.i.
Toxicity Value, mg cation/L
(95% C.I.)
Slope (if applicable)
MRID
(or other Citation)
Classification
NEW Studies Noted
Notes
Water Flea
D. magna
Unknown
21-day NOAEC/ LOAEC
approximately 0.007/ 0.07 (0.01/
0.1 mg a.i./L in paper) based on
reproduction
E118906
(Ha and Choi, 2009)
Supplemental
(qualitatively usable)
NEW
Based on significant (p<0.05) approximately (obtained from visual
inspection of graph in publication) 30% reduction in reproduction
(progeny) at 100 ug /L of paraquat. However, the paper was unclear
whether test substance was paraquat dichloride or cation and whether
measured or nominal. Due to insufficient information, the endpoints are
qualitatively usable to describe risk but not quantitatively usable to
calculate risk, so is qualitative and not quantitatively usable to calculate
risk.
Sub-Acute Toxicity in Whole Sediment 850.1735 and 850.1740 (or similar):
Most sensitive/defensible acute benthic invertebrate sediment-toxicity
endpoint: NOAEC / LOAEC = 0.00072/ 0.0015 mg cation/kg-TOC based
on survival; NOAEC also based on growth (dry weight).
Freshwater
Amphipod
Hyalella
azteca
TGAI (Paraquat
dichloride):
99.4% (97.8%
radiochemical
purity)
10-day NOAEC / LOAEC = 30/ 61
mg cation/kg-dw (0.00072/ 0.0015
mg cation/kg-TOC; 0.060/ 0.120
mg cation/L estimated pore water-
see Notes)
based on survival and growth (dry
weight)
49577003
Acceptable
NEW
Endpoint based on significant (p<0.05) 84% reduction in survival at the
LOAEC; also, for dry weight there was no significant reduction at the
NOAEC, but due to survival reduction at the next higher treatment, the
LOAEC was not determined and is considered to be >0.00072 mg
cation/kg-TOC.
Single application of test substance to sediment with intermittent flow-
through of overlying water and mean-measured sediment (bulk and OC-
normalized). The mean-measured concentrations were total reactive
residue of paraquat cation.
Due to unreliable pore water measurement estimates, the pore water
concentration at the NOAEC and LOAEC were not included in the DER for
estimates of the NOAEC and LOAEC. However, the pore water NOAEC
may be estimated using a simple ratio from the midge study (49577001),
which had usable pore water concentrations: 0.21 4- 90 = adjustment
factor of 0.00233. Using this factor, the estimated pore water NOAEC
would be 0.070 mg cation/L. As a check, in this Hyalella study, two
treatment levels (the lowest and highest) had measureable pore water
concentrations. Using ratios from these data give similar NOAEC pore
water estimates, ranging from 0.071-0.045 mg cation/L, with the highest
113
-------
Species
Tested
Guideline Note
(if Applicable)
Test Substance:
% a.i.
Toxicity Value, mg cation/L
(95% C.I.)
Slope (if applicable)
MRID
(or other Citation)
Classification
NEW Studies Noted
Notes
slightly below (86% of) the estimate using the midge data:
6.3 mg/kg nominal: 5.5 mg cat./kg-dw, 0.013 mg cation/L -Ratio:
0.0024 (Pore water NOEC est. 30*0.0024 = 0.071 mg cation/L
100 mg/kg nominal: 87 mg cat./kg-dw - 0.13 mg cation/L -Ratio:
0.0015 (Pore water NOEC est.: 0.045mg cation/L}
However, because the midge study was conducted using artificial
sediment, and the Hyalella study using natural sediment, the pore water
estimate using the mean ratio from the two measured treatments in the
Hyalella study (0.0024 and 0.0015, mean: 0.0020) seems to be the best
estimate and is used here to estimate the NOAEC and LOAEC; although
the midge ratio estimate gives some support to this estimate,
uncertainty is acknowledged.
Other Endpoints:
Based on Organic Carbon:
0.00072/ 0.0015 mg cation/kg-TOC
based on survival and growth (dry weight)
Midge
Chironomus
ripari us
TGAI (Paraquat
dichloride):
99.4% (97.8%
radiochemical
purity)
10-day NOAEC / LOAEC = 90/ >90
mg cation/kg-dw (0.21/ >0.21 mg
cation/L pore water)
based on survival and growth
(AFDW)
49577001
Acceptable
NEW
Single application of test substance to sediment with intermittent flow-
through of overlying water and mean-measured sediment (bulk and OC-
normalized), mean-measured pore water, and mean-measured overlying
water concentrations. The mean-measured concentrations were total
reactive residue of paraquat cation.
Other Endpoints:
Overlying Water:
NOAEC / LOAEC = 0.090/ >0.090 mg cation/L
based on no significant (p<0.05) reduction in survival or growth (AFDW)
Bulk Sediment:
NOAEC / LOAEC = 0.0047/ >0.0047 mg cation/kg-TOC
based on no significant (p<0.05) reduction in survival or growth (AFDW)
114
-------
Species
Tested
Guideline Note
(if Applicable)
Test Substance:
% a.i.
Toxicity Value, mg cation/L
(95% C.I.)
Slope (if applicable)
MRID
(or other Citation)
Classification
NEW Studies Noted
Notes
Estuarine-
Marine
Amphipod
Leptocheirus
plumulosus
TGAI (Paraquat
dichloride):
99.4% (97.8%
radiochemical
purity)
10-day NOAEC / LOAEC = 99/ >99
mg cation/kg-dw (no pore water
estimate-see Notes)
based on survival
49577002
Acceptable
NEW
Single application of test substance to sediment with static conditions
and mean-measured sediment (bulk and OC-normalized)
concentrations. The mean-measured concentrations were total reactive
residue of paraquat cation. Pore water measured concentrations had
similar problems to those of the Hyalella study, with only detectable
levels in the highest and lowest treatments. However, no further
attempt was made to estimate pore water concentrations for this study
since the saltwater amphipod was not as sensitive as the freshwater
amphipod, Hyalella.
Other Endpoints:
Bulk Sediment:
NOAEC / LOAEC = 0.0025/ >0.0025 mg cation/kg-TOC
based on no significant (p<0.05) reduction in survival
Chronic Toxicity in Whole Sediment NG Chronic Sediment (OECD Guideline 218, or similar):
Most sensitive/defensible chronic benthic invertebrate sediment-
toxicity endpoint: NOAEC / LOAEC = 68/ >68 mg cation/ kg-dw based on
emergence.
Midge
C. riparius
Chronic
TGAI (Paraquat
dichloride):
34.1%
21-day NOAEC / LOAEC = 68/ >68
mg cation (94/ >94 mg TRR)/ kg-
dw (no pore water estimate-see
Notes)
based on emergence
48877201
Supplemental
(quantitatively
usable)
NEW
Static initial-measured concentration of total reactive residues, with
aeration. The study was conducted at a single level of 100 mg Paraquat
ion/kg-dw sediment (nominal concentration). No significant effects were
measured in number/percent emerged or mean time to emergence.
DER reported result as TRR of paraquat dioxide; used conversion: 94*
186.258/257.158 = 68 mg.
Pore water concentrations were not measured in this study. Based on
the bulk sediment NOAEC/ LOAEC values, the midge chronic estimates
from this 21-day study (68/ >68 mg cation/kg-dw) were not as sensitive
as the Hyalella 10-day survival endpoints (30/ 61 mg cation/kg-dw).
Therefore, no further attempt was made to estimate the pore water
concentration. Due to the persistence of paraquat, this is a data gap and
chronic data on Hyalella may be needed.
115
-------
Species
Tested
Guideline Note
(if Applicable)
Test Substance:
% a.i.
Toxicity Value, mg cation/L
(95% C.I.)
Slope (if applicable)
MRID
(or other Citation)
Classification
NEW Studies Noted
Notes
Freshwater Fish Acute Toxicity 850.1075 (or equivalent §72-lA):
Fathead
Minnow
Pimephales
promelas
TGAI: (paraquat
dichloride:
46.3%) 33.5%
cation
96-hr LC50= 4.7 (3.0 to 8.5)
Probit Slope: 4.0 (1.3 to 6.7)
49320303
Acceptable
Most sensitive/defensible freshwater fish and aquatic-phase
amphibians acute endpoint: 96-hr LC50 = 4.7 mg cation/L.
Flow-through study with mean-measured concentrations.
Rainbow Trout
Oncorhynchus
mykiss
Formulation
96-hr EC50 = 6.1
00162736
Supplemental
Rainbow Trout
0. mykiss
Formulation
96-hr EC50 = 8.1 (8.0-8.3)
162738/Acc. No.
264880
Supplemental
Rainbow Trout
0. mykiss
Formulation:
21.2%
96-hr EC50 = 16 (12-20)
Slope: 6.7
40098001
Supplemental
From collection of Mayer & Ellersieck, 1986.
Bluegill
Lepomis
macrochirus
Formulation:
21.2%
96-hr EC50 = 12 (7.8-15)
Slope: 5.4
40098001
Supplemental
From collection of Mayer & Ellersieck, 1986.
Bluegill
L. macrochirus
Formulation:
21.2%
96-hr EC50 = 32.7
162737
Supplemental
From collection of Mayer & Ellersieck, 1986.
Channel
Catfish
Ictalurus
punctatus
TGAI: 42%
96-hr EC50 >100
40098001
Supplemental
From collection of Mayer & Ellersieck, 1986.
Bluegill
L. macrochirus
Paraquat
Chloride - Form
Not specified:
29.1%
96-hr EC50 = 156 (68.3-356) ppm
formulation
Slope: 3.77
113705/ Acc. No.
103609
Supplemental
DER from 1979 - did not state study classification and assumed
supplemental. Additionally, concentrations were stated to be based on
total formulation in mg/L, but specifically what mg/L meant was not
entirely clear. Did not further review since was not the most sensitive
endpoint.
116
-------
Species
Tested
Guideline Note
(if Applicable)
Test Substance:
% a.i.
Toxicity Value, mg cation/L
(95% C.I.)
Slope (if applicable)
MRID
(or other Citation)
Classification
NEW Studies Noted
Notes
Gourami Fish
Trichogaster
trichopterus
30%
96-hr LC50 = approximately 1.41
(paper states is ion)
E172382
(Banaee, et at., 2013)
Supplemental
(qualitatively usable)
NEW
This LC50 is more sensitive than the quantitative fish endpoints that are
available. However, the test substance may have been a formulation
and the paper was unclear as to whether endpoints were measured or
nominal. Other unavailable information included the health of the test
organisms, whether they were cultured or wild caught, and effects at
each treatment level. Due to insufficient information, the endpoints are
qualitatively usable to describe risk but not quantitatively usable to
calculate risk.
Freshwater Aquatic-Phase Amphibian Acute Toxicity 850.1075 (or equivalent §72-lA):
Red-eyed
Treefrog
Agalychnis
callidryas
Unknown
8-day LC50 = approximately 1.24
(1.706 mg/L in paper and NOAEC/
LOAEC of 0.226/0.453 mg/L) based
on weight
E168034
(Ghose, et a!., 2014)
Supplemental
(qualitatively usable)
NEW
Based on weight (although unclear whether wet or dry weight). This LC50
is more sensitive than the quantitative fish endpoints that are available.
However, the duration was longer than 96-hours; the test substance was
likely a formulation (but unclear); the paper was unclear as to whether
endpoints were expressed as paraquat dichloride or cation and whether
measured or nominal. Other unavailable information included the
health of the test organisms, whether they were cultured or wild caught,
and effects at each treatment level. Due to insufficient information, the
endpoints are qualitatively usable to describe risk but not quantitatively
usable to calculate risk.
Fowler's Toad
Bufo
woodhousei
fowleri
TGAI: 42%
96-hr EC50 = 15 (7.8-23)
Slope: 3.3
40098001
Supplemental
From collection of Mayer & Ellersieck, 1986.
Saltwater Fish Acute Toxicity 850.1075 (or equivalent §72-3A):
Sheepshead
Minnow
Cyprinodon
variegatus
TGAI: (paraquat
dichloride:
46.3%) 33.5%
cation
LC50: >41
49320304
Acceptable
NEW
Most sensitive/defensible E/M fish acute endpoint: LC50 >41 mg
cation/L.
Flow-through study with mean-measured concentrations. No mortality
in any treatment; highest concentration tested was 41 mg cation/L
mean measured concentration. No apparent sub-lethal effects were
observed in the control or any of the treatment groups.
117
-------
Species
Tested
Guideline Note
(if Applicable)
Test Substance:
% a.i.
Toxicity Value, mg cation/L
(95% C.I.)
Slope (if applicable)
MRID
(or other Citation)
Classification
NEW Studies Noted
Notes
Longnose
Killifish
Fundulus
similis
Formulation
96-hr EC50 >0.72
40228401
Supplemental
This endpoint is from the U.S. EPA Gulfbreeze lab collection and was not
the most defensible endpoint (did not appear to be tested at high
enough concentrations for definitive endpoint) and, therefore, was not
further investigated to determine if the endpoint is quantitatively usable
or to supply further details.
Fish Chronic Toxicity - Early Life-Stage Test 850.1400 (or equivalent §72-4A):
Most sensitive/defensible freshwater fish chronic endpoint: NOAEC /
LOAEC = 0. 74/ 1.5 mg cation/L based on growth.
The LOAEC of 1.5 mg cation/L was based on significant (p<0.05)
reductions of 18.7% and 13.3% in dry and wet weight, respectively, as
compared to the control.
Fathead
Minnow
P. promelas
Chronic
Early Life-Stage
TGAI: (paraquat
dichloride:
46.3%) 33.5%
cation
33-day NOAEC / LOAEC = 0.74/ 1.5
mg cation/L
based on growth (dry and wet
weight)
49320307
Acceptable
NEW
Due to a 65% reduction in survival at 3.0 mg cation/L (the highest
treatment), that treatment was excluded from growth calculations and
CETIS was rerun. In the CETIS rerun, a 7.6 and 8.8% wet weight drop
from the control level at 0.094 and 0.37 mg cation/L, respectively, and
the 8.9 to 12.4% drop from the control level in the lowest four
treatments, were also determined to be significantly different from the
controls according to Dunnett's (p<0.05). However, the pattern was not
clearly dose-dependent / treatment-related and these were determined
to not be biologically significant, but due to variability, although some
uncertainty is associated with the lower and mid-range treatment levels
(0.094-0.74 mg cation/L).
Using data from this study and MRID 49320303, an acute-to-chronic
ratio (ACR) for the fathead minnow can be calculated as 6.4 (4700/740).
Other Endpoints:
Growth:
Length:
NOAEC: 3.0 mg cation/L
LOAEC: >3.0 mg cation/L (13.3% reduction)
118
-------
Species
Tested
Guideline Note
(if Applicable)
Test Substance:
% a.i.
Toxicity Value, mg cation/L
(95% C.I.)
Slope (if applicable)
MRID
(or other Citation)
Classification
NEW Studies Noted
Notes
Survival - Juvenile Survival on Day-28:
NOAEC: 1.5 mg cation/L
LOAEC: 3.0 mg cation/L (69.6% mortality; 64.7% reduction from control)
Reproduction- Eggs Hatched/Embryo Viability and Time to Hatch:
NOAEC: 3.0 mg cation/L
LOAEC: >3.0 mg cation
Sheepshead
Minnow
C. variegatus
Chronic
Early Life-Stage
TGAI: (paraquat
dichloride:
46.3%) 33.5%
cation
34-day NOAEC / LOAEC = 1.8/ 3.7
mg cation/L
based on growth (length and dry
and wet weights)
49320308
Acceptable
NEW
Most sensitive/defensible saltwater fish chronic endpoint: NOAEC /
LOAEC = 1.8/ 3.7 mg cation/L based on growth.
At the LOAEC of 3.7 mg cation/L, length and wet weight were
significantly (p<0.05) decreased by 5.3 and 11.7%, respectively, and dry
weight was also reduced by 5.1%, although this was not statistically
significant. Flow-through study with mean-measured concentrations
Other Endpoints:
Growth:
Dry Weight:
NOAEC: 3.7 mg cation/L
LOAEC: >3.7 mg cation/L
Reproduction:
Hatching Success and Time to Hatch:
NOAEC: 3.7 mg cation/L
LOAEC: >3.7 mg cation/L
Larval Survival:
NOAEC: 3.7 mg cation/L
LOAEC: >3.7 mg cation/L
Abbreviations: N/A = not applicable; a.i. = active ingredient; TGAI = technical grade active ingredient; TEP = typical end use product; -hr = hour; -wk = week; conc. =
concentration; C.I. = confidence interval; LC/EC/ICxx = lethal/effects/inhibition concentration specifying percent of organisms affected; NOAEC/LOAEC = no/lowest observed
adverse effects concentration; OC = organic carbon; TOC = total organic carbon; dw = dry weight (of sediment).
119
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Toxicity to Terrestrial Vertebrates and Invertebrates
A comprehensive list of available toxicity data for terrestrial invertebrates and vertebrates is found in Table B-2. A summary of data
from most of the studies is found in the problem formulation (USEPA, 2011) and the red-legged frog assessment (USEPA, 2009); the
new data reviewed since the problem formulation are noted as "NEW" in the MRID/Classification column.
Table B-2. Summary of Terrestrial Toxicity Data for Paraquat Expressed as Paraquat Cation.
Species Tested
Guideline Note (if
Applicable)
Test Substance: % a.i.
Toxicity Value
(95% C.I. or standard
deviation if noted)
Slope (if applicable)
MRID
(or other
Citation)
Classification
NEW Studies
Noted
Notes
Avian Acute Oral Toxicity 850.2100 (TG223, or equivalent §71-1):
Zebra Finch
Poephila guttata
Acute Oral
TGAI: (96.1% paraquat
dichloride) 72.4% cation
14-day (single-dose) LD50
= 26.5 mg cation/kg-bw
49349901
Acceptable
NEW
Most sensitive/defensible avian acute dose endpoint: LD50 = 26.5 mg
cation/kg-bw.
Study conducted as TG223 on zebra finch.
Bobwhite Quail
Colinus
virginianus
Acute Oral
TGAI: (study report says
assumed to be 100% active
material)
14-day (single-dose) LD50
= 124 (99-148) mg
cation/kg-bw
Slope: 6.6 (3.5-9.7)
00029001
Acceptable
Mortality, effects to body weight and lethargy were observed in birds
dosed with 115 mg/kg-bw. The slope of the dose-response curve was
(MRID 00029001).
Mallard Duck
Anas
platyrhynchus
Acute Oral
TGAI
N/A
00160000
Invalid
From collection: Hudson et al. 1984.
Mallard Duck
A. platyrhynchus
Acute Oral
TGAI
LD50 = 436.8 mg/kg-bw
00160000
Supplemental
From collection: Hudson et al. 1984.
Mallard Duck
A. platyrhynchus
Acute Oral
TGAI: 32.3% w/w cation
14-day (single-dose) LD50
= 53 mg cation/kg-bw
49378001
Acceptable
NEW
Avian Acute Dietary Toxicity 850.2200 (or equivalent §71-2):
Japanese Quail
Coturnix coturnix
Acute Dietary
Formulation: (29.1%
paraquat dichloride) 21.1%
cation
5-day LC50 = 698 (593-821)
mg cation/kg-diet
Slope: 6.06 (±1.31 sd)
00022923
Acceptable
Most sensitive/defensible avian acute dose endpoint: LC50 = 698 mg
cation/kg-diet.
Study amended in 2011 to re-calculate the endpoint.
120
-------
Species Tested
Guideline Note (if
Applicable)
Test Substance: % a.i.
Toxicity Value
(95% C.I. or standard
deviation if noted)
Slope (if applicable)
MRID
(or other
Citation)
Classification
NEW Studies
Noted
Notes
Bobwhite Quail
C. virginianus
Acute Dietary
Formulation: 29.1%
5-day LC50 = 706 (564-873)
mg cation/kg-diet
Slope: 5.02 (±1.28 sd)
00022923
Acceptable
Study amended in 2011 to re-calculate the endpoint.
Ring-necked
pheasant
Phasianus
colchicus
Acute Dietary
Formulation: 29.1%
5-day LC50 = 1060 (927-
1210) mg cation/kg-diet
Slope: 5.85 (±1.97 sd)
00022923
Acceptable
Study amended in 2011 to re-calculate the endpoint.
Mallard Duck
A. platyrhynchus
Acute Dietary
Formulation: 29.1%
5-day LC50 = 2920 (2470-
3520) mg cation/kg-diet
Slope: 6.77 (±1.28 sd)
00022923
Acceptable
Study amended in 2011 to re-calculate the endpoint.
Mallard Duck
A. platyrhynchus
and
Pheaseant
Acute Dietary
Formulation
N/A
55103/90975/
Acc. No.
180,000
Invalid
In 2011, study was amended to an invalid classification.
Avian Reproduction 850.2300 (or equivalent §71-4
Most sensitive/defensible avian chronic endpoint: NOAEC / LOAEC =
29.4/ 101 mg cation/kg-diet based on reproduction and food
consumption.
Mallard Duck
A. platyrhynchus
Chronic
Reproduction
TGAI: (43.5% paraquat
dichloride) 31.5% cation by
weight
18-wk NOAEC / LOAEC =
29.4/ 101 mg cation/kg-
diet based on
reproduction and food
consumption
00110455
Acceptable
At the LOAEL: significant (p<0.05) reductions of 59.0 % in eggs laid, 24.7%
in viable embryos/egg set, 33.1% in live embryos/egg set, and 8.5% in
mean food consumption.
Marked treatment-related reductions (p<0.01) in the numbers of eggs laid
and viable embryos were observed at the mean-measured 101 mg ai/kg
diet level. Further, significant inhibitions were noted for viable embryos
per egg set and live embryos per egg set (p<0.01) at 101 mg ai/kg; mean
food consumption was also significantly reduced (p<0.05). The original
study had nominal and measured concentrations expressed as cation and
even though the DER has endpoints expressed in mg a.i./kg, the a.i. was
already adjusted to cation.
121
-------
Species Tested
Guideline Note (if
Applicable)
Test Substance: % a.i.
Toxicity Value
(95% C.I. or standard
deviation if noted)
Slope (if applicable)
MRID
(or other
Citation)
Classification
NEW Studies
Noted
Notes
Bobwhite Quail
C. virginianus
Chronic
Reproduction
TGAI: 31.5% cation by weight
18-wk NOAEC / LOAEC =
100 / >100 mg cation/kg-
diet
based on no effects to
reproduction, growth or
survival
00110454
Supplemental
(qualitatively
usable)
No measured effects in highest treatment, 100 mg cation/kg-diet (nominal
concentration).
The study was downgraded in 2018 to supplemental because several
control reproduction validity requirements were not met. The study was
determined to be scientifically sound; however, failure to meet
reproduction validity criteria by the control group resulted in a
Supplemental (Qualitative) classification. The revised DER notes that a
number of control validity requirements were not met in the study:
specifically, the number of 3-week old embryos of viable embryos
averaged 94% (minimum validity requirement of 97%); the percentage of
normal hatchlings of viable embryos averaged 66% (minimum validity
requirement of 85%); and the percentage of normal hatchlings of eggs set
averaged 57% (minimum validity requirement of 71%).
Bobwhite Quail
C. virginianus
Chronic
Reproduction
Screen
TGAI: 31.5% cation by weight
20-wk NOAEC/LOAEC not
established
00110453
Invalid
Per 2018 memo, classified as Invalid due to insufficient replicates, no raw
data submitted, low egg laying response for all birds, and no data on chick
survival.
Avian Reproduction Non-Guideline:
Mallard Duck
A. platyrhynchus
Chronic
Reproduction
TEP: Formulation containing
17.3% paraquat dichloride
50+-d NOAEC/LOAEC =
1.0 / 2.0 lb cation/A
based on reproduction
and survival
43942604
Supplemental
Mallard eggs were sprayed with paraquat dichloride, an application rate of
2.0 lb cation/A increased the number of embryonic deaths (at days 13 and
19) as well as the number of dead embryos in the shell at day 31. At this
concentration, the number of hatchlings and number of chicks surviving to
28 d were also decreased. The resulting NOAEC was 1.0 lb cation/A.
Mallard Duck
A. platyrhynchus
Chronic
Reproduction
TEP: Formulation containing
17.3% paraquat dichloride
20-d NOAEC / LOAEC =
1.45/0.73 lb cation/A
43942604
Supplemental
Mallard eggs were sprayed with paraquat dichloride.
Mallard Duck
A. platyrhynchus
Chronic
Reproduction
TEP: Formulation containing
17.3% paraquat dichloride
NOAEC not determined
based on fertile eggs and
embryo survival
43942605
Supplemental
122
-------
Species Tested
Guideline Note (if
Applicable)
Test Substance: % a.i.
Toxicity Value
(95% C.I. or standard
deviation if noted)
Slope (if applicable)
MRID
(or other
Citation)
Classification
NEW Studies
Noted
Notes
Ring-necked
Pheasant
P. colchicus
Chronic
Reproduction
TEP: Formulation containing
17.3% paraquat dichloride
50-d NOAEC / LOAEC = 0.5
/ 0.72 lb cation/A
based on reproduction
and survival
43942605
Supplemental
Pheasant eggs were sprayed with paraquat dichloride, effects to the
number of eggs hatched and number of 28-d old survivors were observed
at 0.72 lb cation/A, resulting in a NOAEC of 0.36 lb cation/A.
Mallard Duck
A. platyrhynchus
Chronic
% Paraquat not reported
NOAEC not determined
based on growth and
mortality
00162746
Supplemental
This is an open lit submission (Hoffman and Eastin,1982).
Hen
Paraquat (% a.i. unknown)
N/A
00025808/ Acc.
No. 108,000
Supplemental
information
This was a study on the effect of some herbicides on the hatching rate of
hen eggs. A dose of 1 ppm given at different intervals after the
commencement of incubation resulted in a 20% hatch at 2- and 4-days but
a hatch of 80% and above thereafter to the day-16. It was noted that a
dose of 0.15 ppm resulted in 40% hatch and 0.25 ppm in 0% hatch. This is
supplemental information for risk characterization, rather than
quantitative risk calculations.
Hybrid White
Leghorn Strain
Chicken
Reproduction
Paraquat (% a.i. unknown)
14-d NOAEC < 40 ppm
paraquat in water
based on number of
abnormal eggs produced.
55110/Acc. No.
180,000
Supplemental
Toxicant was administered in water rather than feed, and only for 14 days;
test was initiated just after birds reached period of maximum lay and no
water consumption data were provided. Author stated that the 40 ppm
treatment appeared to have no effect on consumption of food or water.
Analysis of paraquat in eggs showed that paraquat rose to about 0.1 ppm
and then declined to below the level of detection (not provided in DER) 6
days after birds were taken off treated diet.
Additionally, the author states that for hen eggs injected directly,
paraquat was the most toxic of 25 herbicides tested and gave complete kill
at a concentration in the egg of 0.3 ppm; also, at the 0.15 ppm level, only
a third hatched. The author speculated that due to paraquat's low
solubility in fat, the egg yolk provided no protection to the embryo and
that paraquat seemed to interfere with metabolic processes specific to
very early and very late development.
Unspecified
Wildlife
Field Study - Paraquat Resin
Soaking in Southern Pines
Program
No dead or injured
recorded.
Effect noted: temporary
Acc. No. 232799
Supplemental
information
These were casual field observations by untrained cooperators using no
control plots. Each cooperator was provided a four-page checklist of
wildlife and asked to report any observed wildlife, noting any sickness,
123
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Species Tested
Guideline Note (if
Applicable)
Test Substance: % a.i.
Toxicity Value
(95% C.I. or standard
deviation if noted)
Slope (if applicable)
MRID
(or other
Citation)
Classification
NEW Studies
Noted
Notes
migration of wildlife away
from areas of human
activity.
injury, or death. Considered supplemental information.
Toxicity to Honey Bees 850.3020 (or equivalent §141-1); the oral test is currently non-guideline:
Honey Bee
Apis mellifera L.
Acute Contact
TEP: EC Formulation
containing 1.67 lb/gal
paraquat dichloride
(estimated to be 25.2% - see
Notes)
48-hr LD50= 52 |jg
cation/bee
43942603
Acceptable
Most sensitive/defensible honey bee acute contact endpoint: LD50= 52
lag cation/bee.
Available data suggest that formulated paraquat is more toxic than the
TGAI.
The DER did not provide the % purity except as lb paraquat dichloride/gal.
Used a label for Gramoxone SL to calculate the purity. The label was for a
2.0 lb paraquat cation/gal formulation and specified 30.1% cation. Used
the following ratio calculation to estimate the percent: 2.0 / 0.301 = 6.74
(cation/gal if 100%); 1.67 / 6.74 = 0.252; so 25.2%.
Honey Bee
A. mellifera
Acute Contact
TGAI: at least 95%
48-hr LD50>35 |ag
cation/bee
05001991
Acceptable
This is an open lit submission (Stevensen, 1978).
Honey Bee
A. mellifera
Acute Contact
TGAI: 99%
48-hr LD50>104 |ag
cation/bee
43942603
Acceptable
Honey Bee
A. mellifera
Acute Oral
TEP: EC Formulation
containing 1.67 lb/gal
paraquat dichloride (25.2%
cation)
48-hr LD50= 22 |jg
cation/bee
43942603
Acceptable
Most sensitive/defensible honey bee acute oral endpoint: LD50= 22 |ig
cation/bee.
Available data suggest that formulated paraquat is more toxic than the
TGAI and that paraquat is more toxic as an oral dose than a contact dose.
For purity estimate, see Notes for the contact study.
Honey Bee
A. mellifera
Acute Oral
TGAI: 99%
48-hr LD50= 37 |jg
cation/bee
43942603
Acceptable
Toxicity to Honey Bees 850.3020 from non-guideline studies:
Honey Bee
A. mellifera
Acute NG (dusting)
TGAI
LD50>6.04 [jg a.i./bee
MRID
00036935/
In this study from the open literature, exposure of honey bees to technical
paraquat through dusting to 6.04 pg a.i./bee resulted in 2.74% mortality.
124
-------
Species Tested
Guideline Note (if
Applicable)
Test Substance: % a.i.
Toxicity Value
(95% C.I. or standard
deviation if noted)
Slope (if applicable)
MRID
(or other
Citation)
Classification
NEW Studies
Noted
Notes
00028772
Honey Bee
A. mellifera
Acute NG
TEP: Formulation of Paraquat
CL was mixed with 20 gal
water with a surfactant
2-d LC50 approximately 4
lb o././A
MRID
00111488/
00132710/ Acc.
No. 252084
Supplemental
In this open literature study (Moffett et a!., 1972), caged bees were
exposed to a direct application of 4 lb a.i./A formulated paraquat. After 2
days, approximately 55% mortality was observed.
Abbreviations: N/A = not applicable; a.i. = active ingredient; TGAI = technical grade active ingredient; TEP = typical end use product; -hr = hour; -wk = week; conc. =
concentration; C.I. = confidence interval; LC/EC/ICxx = lethal/effects/inhibition concentration specifying percent of organisms affected; NOAEC/LOAEC = no/lowest observed
adverse effects concentration.
Toxicity to Aquatic and Terrestrial Plants
A comprehensive list of available toxicity data for aquatic and terrestrial plants is found in Table B-3. A summary of data from most
of the studies is found in the problem formulation (USEPA, 2011) and the red-legged frog assessment (USEPA, 2009); the new data
reviewed since the problem formulation are noted as "NEW" in the MRID/Classification column.
Table B-3. Summary of Aquatic and Terrestrial Plant Toxicity Data for Paraquat Expressed as Paraquat Cation.
Species Tested
Guideline Note (if
Applicable)
Test Substance:
% a.i.
Toxicity Value, mg
cation/L or lb cation/A (as
specified)
(95% C.I.)
Slope (if applicable)
MRID
(or other
Citation)
Classification
NEW Studies
Noted
Notes
Vascular Aquatic Plants 850.4400:
Duckweed
Lemna gibba
TGAI: (Paraquat
dichloride
technical 32.7%):
23.7% cation
(w/w)
14-day EC/IC50 = 0.071
(0.063-0.079) mg cation/L
NOAEC/ LOAEC = 0.023/
0.047 mg cation/L
Slope: 3.27 (-0.53-7.08)1
42601003
Acceptable
Most sensitive/defensible aquatic vascular plant endpoints: NOAEC/ LOAEC of
0.023/ 0.047 based on frond number.
The LOAEC was based on significant (p<0.05) 18% inhibition of frond number.
Endpoints were expressed as nominal concentrations adjusted for purity. Due to
125
-------
Species Tested
Guideline Note (if
Applicable)
Test Substance:
% a.i.
Toxicity Value, mg
cation/L or lb cation/A (as
specified)
(95% C.I.)
Slope (if applicable)
MRID
(or other
Citation)
Classification
NEW Studies
Noted
Notes
based on frond number
problems with the analytical methodology, not all of the treatments had measured
concentrations but those with measurements had 75-94% recoveries.
The NOAEC and LOAEC endpoints noted on the 2011 problem formulation were
based on phytotoxic symptoms, but the one based on frond number was used in
this assessment because they are more defensible. The phytotoxic endpoint was
based on descriptive symptoms: plants in the 0.023 mg cation/L treatment were
noted to be slightly chlorotic with reduced root growth at test termination.
However, there was no measurable effect in frond number (0% inhibition) or
weight (0% inhibition) at the LOAEC. At the next higher concentration of 0.047 mg
cation/L, was 18% (significant at p<0.05 by Dunnett's) inhibition in frond number
with a dose:dependant (and significant at p<0.05) 74% reduction at 0.093 mg
cation/L treatment. At 0.093 mg cation/L, there was also a significant 62%
reduction in dry weight at 0.093 mg cation/L. A slope of 3.27 (-0.53-7.08) is
available from the probit analysis with an accompanying EC50 of 0.073 mg cation/L
based on frond number but the EC50 reported in the problem formulation (and
used in this analysis) was calculated using the moving average method.
Other Endpoints:
NOAEC/ LOAEC = 0.012/ 0.023 mg cation/L
Based on phytotoxicity; plants in the 0.023 mg cation/L treatment were noted to
be slightly chlorotic with reduced root growth at test termination.
Non-Vascular Aquatic Plants Guideline 850.4500:
Freshwater
Diatom
Navicula
pelliculosa
TGAI (Paraquat
dichloride
technical 32.7%):
23.7% cation
4-day EC/IC50 = 0.00040
mg cation/L
NOAEC/ LOAEC =
0.00016/ 0.00033 mg
cation/L
Slope: 4.08 (-0.19-8.26)1
based on cell density
42601006
Acceptable
Most sensitive/defensible non-vascular plant endpoints: NOAEC/ LOAEC =
0.00016/ 0.00033 mg cation/L based on cell density.
The LOAEC was based on biologically significant 54% inhibition in cell density at
the LOAEC, followed by dose:dependent pattern of 79 and 97% respective levels of
inhibition at the next two higher treatments. Endpoints were expressed as
estimated mean-measured concentrations, i.e., they were based on nominal
concentrations adjusted using analytical results. Concentrations of the primary
and intermediate stocks were measured at test initiation and termination and had
126
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Species Tested
Guideline Note (if
Applicable)
Test Substance:
% a.i.
Toxicity Value, mg
cation/L or lb cation/A (as
specified)
(95% C.I.)
Slope (if applicable)
MRID
(or other
Citation)
Classification
NEW Studies
Noted
Notes
68-90% recoveries. A slope of 4.08 (-0.19-8.26) is available from the probit analysis
with an accompanying EC50 of 0.00038 mg cation/L based on cell density but the
EC50 reported in the problem formulation (and used in this analysis) was calculated
using the moving average method.
Other Endpoints:
Growth Rate:
NOAEC/ LOAEC = 0.00046/ 0.00093 mg cation/L based on significant (p<0.05) 45%
inhibition.
AUC:
NOAEC/ LOAEC = 0.00046/ 0.00093 mg cation/L based on significant (p<0.05) 78%
inhibition.
Freshwater
Diatom
N. pelliculosa
TGAI (Paraquat
dichloride
technical): 32.6%
Non-Guideline Alteration
of Study to Include
Sediment:
4-day EC/IC50 >0.623 mg
cation/L
NOAEC/ LOAEC = 0.188/
0.623 mg cation/L
based on growth rate
48877202
Supplemental
(quantitatively
usable)
New
NOAEC/LOAEC of 0.188/ 0.623 mg cation./L based on significant (p<0.05) 20%
reduction in growth rate; concentrations were initial-measured paraquat
dichloride concentrations.
This study was altered in an attempt to address sediment toxicity by including a
three gram bottom layer of sandy loam in each test vessel to represent sediment.
Other Endpoints:
Growth Rate:
EC/IC05 = 0.0133 (NA to 0.905) mg/L
Yield:
EC/IC05 = 0.488 (NA to 0.617) mg/L
EC/ICso = 0.643 (0.605 to 0.684) mg/L
NOAEC/LOAEC = 0.623/ >0.623 mg/L
Biomass:
EC/ICso = 0.632 (0.581 to 0.687) mg/L
NOAEC/LOAEC = 0.623/ >0.623 mg/L
Bluegreen Algae
Anabaenaflos-
aquae
TGAI (Paraquat
dichloride
technical): 32.7%
5-day EC/IC50 = 0.011
(0.010-0.012) mg cation/L
NOAEC/ LOAEC = 0.0023/
42601005
Acceptable
127
-------
Species Tested
Guideline Note (if
Applicable)
Test Substance:
% a.i.
Toxicity Value, mg
cation/L or lb cation/A (as
specified)
(95% C.I.)
Slope (if applicable)
MRID
(or other
Citation)
Classification
NEW Studies
Noted
Notes
0.0046 mg cation/L
Slope: 8.46 (-41.0-57.9)1
based on cell density
Green Algae
Selenastrum
capricornutum
TGAI (Paraquat
dichloride
technical): 32.7%
4-day EC/IC50 = 0.23 mg
cation/L
NOAEC/ LOAEC =
0.058/0.140 mg cation/L
Slope: 3.26 (1.11-5.42)1
based on cell density
42601002
Acceptable
Marine Diatom
Skeletonema
costatum
TGAI (Paraquat
dichloride
technical): 32.7%
4-day EC/IC50 = 2.06 mg
cation/L
NOAEC/ LOAEC = 0.160/
0.340 mg cation/L
Slope: 1.53 (1.36-1.71)
based on cell density
42601004
Acceptable
Hapatophyte
Algae
Isochrysis galbana
Information not
determined at
time of
assessment
10-day EC/IC50 = 3.60 mg
cation/L
NOAEC= NA
40228401
Supplemental
This endpoint is from the U.S. EPA Gulfbreeze lab collection and was not the most
sensitive endpoint and, therefore, was not further investigated to determine if the
endpoint is quantitatively usable or to supply further details.
Marine Diatom
Phaeodactylum
tricornutum
Information not
determined at
time of
assessment
10-day EC/IC50 = 7.20 mg
cation/L
NOAEC= NA
40228401
Supplemental
This endpoint is from the U.S. EPA Gulfbreeze lab collection and was not the most
sensitive endpoint and, therefore, was not further investigated to determine if the
endpoint is quantitatively usable or to supply further details.
Green Algae
Dunaliella
tertiolecta
Information not
determined at
time of
assessment
10-day EC/IC50 = 14.4 mg
cation/L
NOAEC= NA
40228401
Supplemental
This endpoint is from the U.S. EPA Gulfbreeze lab collection and was not the most
sensitive endpoint and, therefore, was not further investigated to determine if the
endpoint is quantitatively usable or to supply further details.
Green Algae
Chlorococcum sp.
Information not
determined at
time of
assessment
10-day EC/IC50 = 36.0 mg
cation/L
NOAEC= NA
40228401
Supplemental
This endpoint is from the U.S. EPA Gulfbreeze lab collection and was not the most
sensitive endpoint and, therefore, was not further investigated to determine if the
endpoint is quantitatively usable or to supply further details.
128
-------
Species Tested
Guideline Note (if
Applicable)
Test Substance:
% a.i.
Toxicity Value, mg
cation/L or lb cation/A (as
specified)
(95% C.I.)
Slope (if applicable)
MRID
(or other
Citation)
Classification
NEW Studies
Noted
Notes
Tier II Seedling Emergence 850.4100:
Oat
Avena sativa
TEP: (Formulation
A7813Q) cation:
22.4% (wt/wt) as
free paraquat
cation [plus 0.14%
(wt/wt) as emetic]
14-day EC/IC25 = 0.635 lb
cation/A
NOAEL/LOAEL = 0.28/0.57
lb cation/A
Slope: N/A
Endpoint: emergence and
survival
49320310
Supplemental
(quantitatively
usable)
NEW
Most sensitive/defensible monocot endpoints: EC/IC25 = 0.635 lb cation/A;
NOAEL/ LOAEL = 0.28/ 0.57 lb cation/A based on emergence and survival.
The NOAEL/LOAEL of 0.28/ 0.57 lb cation/A was based on significant (p<0.05)
inhibition in oat survival and emergence, reductions of 21.1 and 23.7% at 0.57 and
1.13 lb cation/A treatment levels, respectively (p<0.05); all endpoints were based
on measured concentrations. The 0.14 and 0.28 lb cation/A treatments also had a
15.8% reduction, which were not statistically significant and the level was the same
effect at two treatment levels; this was not considered treatment related, although
some uncertainty is acknowledged. Overall, the effects seen in emergence and
survival in the higher treatments appear to be dose:dependent, although the height
and weight seem to go up when the weak ones died. Additionally, CETIS estimated
the IC05 to be 0.00277, which was below the lowest treatment, and not usable.
Perennial Ryegrass
Lolium perenne
TEP: (Formulation
A7813Q) cation:
22.4% (wt/wt) as
free paraquat
cation [plus 0.14%
(wt/wt) as emetic]
14-day EC/IC25> 0.57 lb
cation/A
NOAEL = 0.57 lb cation/A
Endpoint: emergence and
survival
49320310
Supplemental
(quantitatively
usable)
NEW
The NOAEL/ LOAEL of 0.57/ 1.13 lb cation/A also applies to height and weight. The
dose:response patterns for ryegrass height and biomass (and emergence and
survival to a lesser degree) were not linear and not clearly treatment related at the
lower treatment levels, making the endpoints unclear; however, the 15.3%, and
25.7%, reductions in height and weight, and the 25.0% reduction in both
emergence and survival, at the highest treatment level (1.13 lb cation/A) could not
be discounted as biologically significant, even though they were not statistically
significant. The NOAEL was assigned from visual inspection of the data; all
endpoints were based on measured concentrations. Additionally, CETIS estimated
an IC25of 0.35 (0.0906-2.23); however the % effect went back up to only 3% in the
0.57 lb cation/A treatment and so the data point was not included in the table.
Corn
Zea mays
TEP: (Formulation
Gramoxone Extra):
294 g a.i./L;
approx. 19.2%
cation
21-day EC/IC25> 0.67 lb
cation/A
NOAEL = 0.67 lb cation/A
Endpoint: no effects to
emergence or growth (dry
wt.)
42639601
Acceptable
The DER said that the formulation contained 294 g a.i./L (a.i. was paraquat
dichloride; this converts to 2.45 lb a.i./gal); looked up label for Gramoxone Extra
and it specified a 3.454 lb salt per gal and 2.5 lb paraquat cation per gal) and 37.3%
a.i.; using a simple ratio conversion, estimated that the formulation contained
26.5% salt, or 19.2% cation. Growth was measured by dry weight and growth stage
(did not pursue the definition since was not most sensitive endpoint); also seedling
129
-------
Species Tested
Guideline Note (if
Applicable)
Test Substance:
% a.i.
Toxicity Value, mg
cation/L or lb cation/A (as
specified)
(95% C.I.)
Slope (if applicable)
MRID
(or other
Citation)
Classification
NEW Studies
Noted
Notes
damage was notes as unaffected.
Corn
Z mays
TEP: (Formulation
A7813Q) cation:
22.4% (wt/wt) as
free paraquat
cation [plus 0.14%
(wt/wt) as emetic]
14-day EC/IC25> 1.04 lb
cation/A
NOAEL = 1.04 lb cation/A
Slope: N/A
Endpoint: none (height,
weight, emergence and
survival measured)
49320310
Supplemental
(quantitatively
usable)
NEW
See below for more information; all endpoints were based on measured
concentrations.
Onion
Allium cepa
TEP: (Formulation
A7813Q) cation:
22.4% (wt/wt) as
free paraquat
cation [plus 0.14%
(wt/wt) as emetic]
14-day EC/IC25> 1.13 lb
cation/A
NOAEL = 1.13 lb cation/A
Endpoint: none (height,
weight, emergence and
survival measured)
49320310
Supplemental
(quantitatively
usable)
NEW
See below for more information; all endpoints were based on measured
concentrations.
Purple Nutsedge
Cyperus rotundus
TEP: (Formulation
Gramoxone Extra):
294 g a.i./L;
approx. 19.2%
cation
21-day EC/IC25> 0.67 lb
cation/A
NOAEL = 0.67 lb cation/A
Endpoint: no effects to
emergence or growth (dry
wt.)
42639601
Acceptable
Growth was measured by dry weight and growth stage (did not pursue the
definition since was not most sensitive endpoint); also seedling damage was notes
as unaffected. For information about purity estimate, see note (above) for the corn
endpoint.
Wild Oat
Avena fatua
Winter Wheat
Triticum aestrivum
TEP: (Formulation
Gramoxone Extra):
294 g a.i./L;
approx. 19.2%
cation
Not available
42639601
Invalid
For wild oat and winter wheat, the DER states that wild oat and winter wheat are
invalid due to poor control emergence. For information about purity estimate, see
note (above) for the corn endpoint.
Dicot:
Cocklebur
Xanthium
strumarium
TEP: (Formulation
Gramoxone Extra):
294 g a.i./L;
approx. 19.2%
cation
21-day EC/IC25 = 0.67 lb
cation/A
NOAEL/LOAEL = 0.171/
0.341 lb cation/A
Endpoint: emergence
42639601
Acceptable
Most sensitive/defensible dicot endpoints: EC/IC25 = 0.67 lb cation/A; NOAEL/
LOAEL= 0.171/ 0.341 lb cation/A based on emergence.
The NOAEL/ LOAEL of 0.171/ 0.341 lb cation/A was based on a biologically
(although not statistically) significant at p<0.05) 20.5% reduction in emergence at
the LOAEL, along with demonstration of a dose-related general decrease in
emergence with increasing treatment rate, although the dose:response was not
130
-------
Species Tested
Guideline Note (if
Applicable)
Test Substance:
% a.i.
Toxicity Value, mg
cation/L or lb cation/A (as
specified)
(95% C.I.)
Slope (if applicable)
MRID
(or other
Citation)
Classification
NEW Studies
Noted
Notes
completely linear. The number of days to emergence was unaffected. The original
DER (1996) had erroneously listed the second highest treatment as the NOAEL
(corresponding to 0.341 lb cation/A) but this was thought to be an error, because
the next higher treatment (the LOAEL) actually had less reduction in emergence
and the DER was amended to correct the error.
Growth was measured by dry weight and growth stage (did not pursue the
definition since was not most sensitive endpoint); also seedling damage was notes
as unaffected. For information about purity estimate, see note (above) for the corn
endpoint.
Morningglory
Ipomoea hederacea
TEP: (Formulation
Gramoxone Extra):
294 g a.i./L;
approx. 19.2%
cation
21-day EC/IC25> 0.67 lb
cation/A
NOAEL = 0.67 lb cation/A
Endpoint: no effects to
emergence or growth (dry
wt.)
42639601
Acceptable
Growth was measured by dry weight and growth stage (did not pursue the
definition since was not most sensitive endpoint); also seedling damage was notes
as unaffected. Morningglory appeared to be affected by seedling damage on day-7,
but had recovered by day-14. Also, all treatments had significant reduction in dry
weight on day-21, but this was thought to be due to one uncharacteristically high
dry weight measurement in the control and since no visual damage was apparent
after day-14, the reduction was not believed to be biologically significant.
For information about purity estimate, see note (above) for the corn endpoint.
Oilseed Rape
Brassica napus
Soybean
Glycine max
Sugar Beet
Beta vulgaris
Velvetleaf
AbutHon
theophrasti
TEP: (Formulation
Gramoxone Extra):
294 g a.i./L;
approx. 19.2%
cation
21-day EC/IC25> 0.67 lb
cation/A
NOAEL = 0.67 lb cation/A
Endpoint: no effects to
emergence or growth (dry
wt.)
42639601
Acceptable
Growth was measured by dry weight and growth stage (did not pursue the
definition since was not most sensitive endpoint); also seedling damage was notes
as unaffected.
For information about purity estimate, see note (above) for the corn endpoint.
Oilseed rape
TEP: (Formulation
14-day EC/IC25> 1.04 lb
49320310
See below for more information; all endpoints were based on measured
131
-------
Species Tested
Guideline Note (if
Applicable)
Test Substance:
% a.i.
Toxicity Value, mg
cation/L or lb cation/A (as
specified)
(95% C.I.)
Slope (if applicable)
MRID
(or other
Citation)
Classification
NEW Studies
Noted
Notes
B. napus
A7813Q) cation:
22.4% (wt/wt) as
free paraquat
cation [plus 0.14%
(wt/wt) as emetic]
cation/A
NOAEL = 1.04 lb cation/A
Slope: N/A
Endpoint: none (height,
weight, emergence and
survival measured)
Supplemental
(quantitatively
usable)
NEW
concentrations.
Common bean
Phaseolus vulgaris
See below for more information; all endpoints were based on measured
concentrations.
Cucumber
Cucumis sativa
Soybean
G. max
Radish
Raphanus sativus
TEP: (Formulation
A7813Q) cation:
22.4% (wt/wt) as
free paraquat
cation [plus 0.14%
(wt/wt) as emetic]
14-day EC/IC25> 1.13 lb
cation/A
NOAEL = 1.13 lb cation/A
Endpoint: none (height,
weight, emergence and
survival measured)
49320310
Supplemental
(quantitatively
usable)
NEW
Tomato
Lycopersicon
esculentum
Tier II Vegetative Vigor 850.4150:
Monocot:
Perennial Ryegrass
L. perenne
TEP: (Formulation
A7813Q) cation:
22.4% (wt/wt) as
free paraquat
cation [plus 0.14%
(wt/wt) as emetic]
21-day EC/IC25 = 0.0208
(0.016-0.0253) lb cation/A
NOAEL = 0.018 lb cation/A
Slope: N/A
Endpoint: dry weight
49320309
Acceptable
NEW
Most sensitive/defensible monocot endpoints: EC/IC25 = 0.0208 lb cation/A;
NOAEL/ LOAEL = 0.018/0.033 lb cation/A based on dry weight.
The NOAEL/LOAEL of 0.018/0.033 lb cation/A was based on significant (p<0.05)
59.5% inhibition at the LOAEL of 0.033 lb cation/A, followed by a dose:dependent
95.4% inhibition at 0.11 lb cation/A; all endpoints were based on measured
concentrations. See below for more information.
Corn
Z. mays
TEP: (Gramoxone
Extra); 1,1-
dimethyl-4,4-
28-d EC/IC25 = 0.16 (0.073-
0.36) lb cation/A
NOAEL/ LOAEL = 0.064/
42601001
Supplemental
(may be used
For corn and six dicots, the original DER classified the studies as acceptable. These
endpoints were downgraded by a 2010 addendium because of deviations from the
study protocol, chiefly 5 or 6 plants (rather than the recommended 10) were
132
-------
Species Tested
Guideline Note (if
Applicable)
Test Substance:
% a.i.
Toxicity Value, mg
cation/L or lb cation/A (as
specified)
(95% C.I.)
Slope (if applicable)
MRID
(or other
Citation)
Classification
NEW Studies
Noted
Notes
bipyridylium
dichloride; 29.4%
a.i. w/v.
0.129 lb cation/A
Endpoint: dry weight
quantitatively)
included in each replicate and height was not measured. However, the dry weight
endpoints may be used quantitatively for risk calculation.
Corn
Z mays
TEP: (Formulation
A7813Q) cation:
22.4% (wt/wt) as
free paraquat
cation [plus 0.14%
(wt/wt) as emetic]
21-day EC/IC25 = 0.0271 lb
cation/A
NOAEL = 0.018 lb cation/A
Endpoint: dry weight
49320309
Acceptable
NEW
Significant decrease in corn weight, inhibition of 36.5 to 74.6% from the 0.033 to
the 0.57 lb cation/A treatment level compared to the negative control (p<0.05). An
IC25 of 0.0122 lb cation/A, estimated by CETIS using non-linear regression, did not
appear reasonable, given the slightly higher NOAEL, which did appear to be a
convincing measured no-effect level. This was likely due to the significant lack of fit.
The author estimate using linear interpolation, converted to cation, of 0.0271 lb
cation/A was considered a better estimate and reported. See below for more
information; all endpoints were based on measured concentrations.
Oat
A. sativa
TEP: (Formulation
A7813Q) cation:
22.4% (wt/wt) as
free paraquat
cation [plus 0.14%
(wt/wt) as emetic]
21-day EC/IC25 = 0.0416 lb
cation/A
NOAEL = 0.033 lb cation/A
Endpoint: dry weight
49320309
Acceptable
NEW
Significant decrease in oat weight, inhibition of 40 to 77% at the >0.071 lb cation/A
treatment levels compared to the negative control (p<0.05). See below for more
information; all endpoints were based on measured concentrations.
Onion
A. cepa
TEP: (Formulation
A7813Q) cation:
22.4% (wt/wt) as
free paraquat
cation [plus 0.14%
(wt/wt) as emetic]
21-day EC/IC25 = 0.0208 lb
cation/A
NOAEL = 0.018 lb cation/A
Endpoint: height
49320309
Acceptable
NEW
Significant decrease in onion height, inhibition of 57.7 and 54.3% at the 0.071 and
0.28 lb cation/A treatment levels, respectively, compared to the negative control
(p<0.05). See below for more information; all endpoints were based on measured
concentrations.
Purple Nutsedge
C. rotundus
Wild Oat
A. fatua
Winter Wheat
T. aestrivum
TEP: (Gramoxone
Extra); 1,1-
dimethyl-4,4-
bipyridylium
dichloride; 29.4%
a.i. w/v.
Not available
42601001
Invalid
Winter wheat, purple nutsedge, and wild oat were treated with insecticide, and so,
their results were determined to be invalid.
Dicot:
TEP: (Formulation
21-day EC/IC25 = 0.0217 lb
49320309
Most sensitive/defensible dicot endpoints: EC/IC25 = 0.0217 lb cation/A; NOAEL/
133
-------
Species Tested
Guideline Note (if
Applicable)
Test Substance:
% a.i.
Toxicity Value, mg
cation/L or lb cation/A (as
specified)
(95% C.I.)
Slope (if applicable)
MRID
(or other
Citation)
Classification
NEW Studies
Noted
Notes
Soybean
G. max
A7813Q) cation:
22.4% (wt/wt) as
free paraquat
cation [plus 0.14%
(wt/wt) as emetic]
cation/A
NOAEL = 0.0048 lb cation/A
Endpoint: height
Acceptable
NEW
LOAEL = 0.0048/0.018 based on height.
NOAEL/LOAEL of 0.0048/0.018 based on significant (p<0.05) decrease in soybean
height of 19.8% at 0.018 lb cation/A, followed by dose:dependent pattern of
inhibition of 39.0% and 46.2% at the next two higher treatment levels compared to
the negative control. See below for more information; all endpoints were based on
measured concentrations.
Soybean
G. max
TEP: (Gramoxone
Extra); 1,1-
dimethyl-4,4-
bipyridylium
dichloride; 29.4%
a.i. w/v.
28-d EC/IC25 = 0.0905
(0.0211-0.419) lb cation/A
NOAEL/ LOAEL = 0.0162/
0.0323 lb cation/A
Endpoint: dry weight
42601001
Supplemental
(may be used
quantitatively)
For the six dicots, the original DER classified the studies as acceptable. These
endpoints were downgraded by a 2010 addendium because of deviations from the
study protocol, chiefly 5 or 6 plants (rather than the recommended 10) were
included in each replicate and height was not measured. However, the dry weight
endpoints may be used quantitatively for risk calculation.
Cocklebur
X. strumarium
TEP: (Gramoxone
Extra); 1,1-
dimethyl-4,4-
bipyridylium
dichloride; 29.4%
a.i. w/v.
28-d EC/IC25 = 0.014 (0.01-
0.019) lb cation/A
EC/IC05 = 0.0065 lb cation/A
Endpoint: dry weight
42601001
Supplemental
(may be used
quantitatively)
For the six dicots, the original DER classified the studies as acceptable. These
endpoints were downgraded by a 2010 addendium because of deviations from the
study protocol, chiefly 5 or 6 plants (rather than the recommended 10) were
included in each replicate and height was not measured. However, the dry weight
endpoints may be used quantitatively for risk calculation.
Common bean
P. vulgaris
TEP: (Formulation
A7813Q) cation:
22.4% (wt/wt) as
free paraquat
cation [plus 0.14%
(wt/wt) as emetic]
21-day EC/IC25 = NC
(possibly >0.28 lb cation/A
- information for
qualitative use)
NOAEL = 0.018 lb cation/A
Endpoint: height
49320309
Acceptable
NEW
Significant decrease in common bean height, inhibition of 20.9% and 20.2% at the
0.071 and 0.28 lb cation/A treatment levels, respectively, compared to the negative
control (p<0.05). The IC25 is qualitatively >0.28 (the highest treatment level tested),
but with 20-21% height reduction at the top two treatments, this is uncertain. See
below for more information; all endpoints were based on measured
concentrations.
Cucumber
C. sativa
TEP: (Formulation
A7813Q) cation:
22.4% (wt/wt) as
free paraquat
cation [plus 0.14%
(wt/wt) as emetic]
21-day EC/IC25 = 0.0887 lb
cation/A
NOAEL = 0.018 lb cation/A
Endpoint: survival
49320309
Acceptable
NEW
Significant decrease in cucumber survival, inhibition of 33 and 48%, respectively, at
the 0.071 and 0.28 lb cation/A treatment levels compared to the negative control
(p<0.05). See below for more information; all endpoints were based on measured
concentrations.
Morningglory
TEP: (Gramoxone
28-d EC/IC25 0.0989
42601001
For the six dicots, the original DER classified the studies as acceptable. These
134
-------
Species Tested
Guideline Note (if
Applicable)
Test Substance:
% a.i.
Toxicity Value, mg
cation/L or lb cation/A (as
specified)
(95% C.I.)
Slope (if applicable)
MRID
(or other
Citation)
Classification
NEW Studies
Noted
Notes
/. hederacea
Extra); 1,1-
dimethyl-4,4-
bipyridylium
dichloride; 29.4%
a.i. w/v.
(0.0173-0.175) lb cation/A
NOAEL/ LOAEL = 0.0646/
0.129 lb cation/A
Endpoint: dry weight
Supplemental
(may be used
quantitatively)
endpoints were downgraded by a 2010 addendium because of deviations from the
study protocol, chiefly 5 or 6 plants (rather than the recommended 10) were
included in each replicate and height was not measured. However, the dry weight
endpoints may be used quantitatively for risk calculation.
Oilseed rape
B. napus
TEP: (Gramoxone
Extra); 1,1-
dimethyl-4,4-
bipyridylium
dichloride; 29.4%
a.i. w/v.
28-d EC/IC25 = 0.0410
(0.0259-0.0526) lb cation/A
NOAEL/ LOAEL = 0.0162/
0.0323 lb cation/A
Endpoint: dry weight
42601001
Supplemental
(may be used
quantitatively)
For the six dicots, the original DER classified the studies as acceptable. These
endpoints were downgraded by a 2010 addendium because of deviations from the
study protocol, chiefly 5 or 6 plants (rather than the recommended 10) were
included in each replicate and height was not measured. However, the dry weight
endpoints may be used quantitatively for risk calculation.
Oilseed rape
B. napus
TEP: (Formulation
A7813Q) cation:
22.4% (wt/wt) as
free paraquat
cation [plus 0.14%
(wt/wt) as emetic]
21-day EC/IC25 = 0.0325 lb
cation/A
NOAEL = 0.018 lb cation/A
Endpoint: dry weight
49320309
Acceptable
NEW
Significant decrease in oilseed rape weight, inhibition of 44.6 and 33.4% at the
0.071 and 0.28 lb cation/A treatment levels, respectively, compared to the negative
control (p<0.05). See below for more information; all endpoints were based on
measured concentrations.
Radish
R. sativus
TEP: (Formulation
A7813Q) cation:
22.4% (wt/wt) as
free paraquat
cation [plus 0.14%
(wt/wt) as emetic]
21-day EC/IC25 = 0.162 lb
cation/A
NOAEL = 0.018 lb cation/A
Endpoint: height
49320309
Acceptable
NEW
Significant decrease in radish height, inhibition of 10.2-28.5% at the >0.033 lb
cation/A treatment levels compared to the negative control (p<0.05). See below for
more information; all endpoints were based on measured concentrations.
Sugar Beet
B. vulgaris
TEP: (Gramoxone
Extra); 1,1-
dimethyl-4,4-
bipyridylium
dichloride; 29.4%
a.i. w/v.
28-d EC/IC25 = 0.0176
(0.00230-0.0350) lb
cation/A
NOAEL/ LOAEL = 0.0323/
0.0646 lb cation/A
Endpoint: dry weight
42601001
Supplemental
(may be used
quantitatively)
For the six dicots, the original DER classified the studies as acceptable. These
endpoints were downgraded by a 2010 addendium because of deviations from the
study protocol, chiefly 5 or 6 plants (rather than the recommended 10) were
included in each replicate and height was not measured. However, the dry weight
endpoints may be used quantitatively for risk calculation.
Tomato
L. esculentum
TEP: (Formulation
A7813Q) cation:
22.4% (wt/wt) as
21-day EC/IC25 = 0.0422 lb
cation/A
NOAEL = 0.033 lb cation/A
49320309
Acceptable
NEW
Significant decrease in tomato weight, inhibition of 42.9 to 64.7% from the 0.071 to
the 0.57 lb cation/A treatment level compared to the negative control (p<0.05). See
below for more information; all endpoints were based on measured
135
-------
Species Tested
Guideline Note (if
Applicable)
Test Substance:
% a.i.
Toxicity Value, mg
cation/L or lb cation/A (as
specified)
(95% C.I.)
Slope (if applicable)
MRID
(or other
Citation)
Classification
NEW Studies
Noted
Notes
free paraquat
cation [plus 0.14%
(wt/wt) as emetic]
Endpoint: dry weight
concentrations.
Velvetleaf
A. theophrasti
TEP: (Gramoxone
Extra); 1,1-
dimethyl-4,4-
bipyridylium
dichloride; 29.4%
a.i. w/v.
28-d EC/IC25 = 0.0448
(0.0232-0.0659) lb cation/A
NOAEL/ LOAEL = 0.0323/
0.0646 lb cation/A
Endpoint: dry weight
42601001
Supplemental
(may be used
quantitatively)
For the six dicots, the original DER classified the studies as acceptable. These
endpoints were downgraded by a 2010 addendium because of deviations from the
study protocol, chiefly 5 or 6 plants (rather than the recommended 10) were
included in each replicate and height was not measured. However, the dry weight
endpoints may be used quantitatively for risk calculation.
Abbreviations: N/A = not applicable; NC = not calculable; a.i. = active ingredient; AUC = area under the curve; TGAI = technical grade active ingredient; TEP = typical end use
product; -hr = hour; conc. = concentration; C.I. = confidence interval; LC/EC/ICxx = lethal/effects/inhibition concentration specifying percent of organisms affected; NOAEC (or
NOAEL) = no-observed adverse effect concentration (or level); LOAEC/L) = lowest observed adverse effect concentration (level).
1Note: Slope based on Probit method, but reported endpoint based on moving average method.
Summary of Information on Most Sensitive Parameters by Species (lb cation/A) from 14-Day Seedling Emergence Study MRID 49320310.
Species
Endpoint
NOEC
ECos
EC25
ECso
Common bean
None
1.13
NC
>1.13
>1.13
Cucumber
Height
1.13
0.316
>1.13
>1.13
Oat
Emergence/Survival
0.28
NC
[1.16 (weight)]
0.635
>1.13
Onion
None
1.13
NC
>1.13
>1.13
Perennial Ryegrass
Emergence/Survival
0.57
[also height/ weight]
NC
[1.03 (height)]
>0.57
[1.14 (height/weight)]
>1.13
Radish
None
1.13
NC
>1.13
>1.13
Soybean
None
1.13
NC
>1.13
>1.13
Tomato
None
1.13
NC
>1.13
>1.13
Corn
None
1.04
NC
>1.04
>1.04
Oilseed Rape
None
1.04
NC
>1.04
>1.04
Abbreviations: NC = not calculable; LC/EC/ICxx = lethal/effects/inhibition concentration specifying percent of organisms affected; NOAEC (or NOAEL) = no-observed adverse
effect concentration (or level).
136
-------
Summary of Information on Most Sensitive Parameters by Species (lb cation/A) from 21-Day Vegetative Vigor Study MRID 49320309.
Species
Endpoint
NOAEL
ECos
EC25
ECso
Common bean
Height
0.018
0.00302
NC
(possibly >0.28, qualitative
estimate)
>0.28
Cucumber
Survival
0.018
0.0215
0.0887
0.238
Oat
Dry Weight
0.033
0.0124
0.0416
0.0964
Onion
Height
0.018
0.00166
0.0297
0.121
Perennial Ryegrass
Dry Weight
0.018
0.0113
0.0208
0.0316
Radish
Height
0.018
0.00824
0.162
>0.28
Soybean
Height
0.0048
0.00059
0.0217
0.265
Tomato
Dry Weight
0.033
0.00579
0.0422
0.168
Corn
Dry Weight
0.018
NC
0.0271
0.0716
Oilseed Rape
Dry Weight
0.018
0.000228
0.0325
>0.28
Abbreviations: NC = not calculable; LC/EC/ICxx = lethal/effects/inhibition concentration specifying percent of organisms affected; NOAEC (or NOAEL) = no-observed adverse
effect concentration (or level).
References Cited in This Appendix:
Hoffman, D.J. and W.C. Eastin, Jr. 1982. "Effects of Lindane, Paraquat, Toxaphene, and 2,4,5-Trichlorophenoxyacetic Acid on Mallard
Embryo Development." Arch. Environ. Contam. Toxicol. 11: 79-86.
Hudson, R.; Tucker, R.; Haegele, M. 1984. "Handbook of toxicity of pesticides to wildlife: Second edition." US Fish and Wildlife
Service: Resource Publication 153. 91 pp.
Mayer, F. 1986. "USEPA Gulfbreeze Estuarine Toxicity Tests - marine algaes, brown shrimp, oyster, longnose killifish."
Mayer, F.; Ellersieck, M. 1986. "Manual of Acute Toxicity: Interpretation and Data Base for 410 Chemicals and 66 Species of
Freshwater Animals." US Fish & Wildlife Service, Resource Publication 160. 579 pp.
137
-------
Stevenson, J.H. 1978. "The Acute Toxicity of Unformulated Pesticides to Worker Honey Bees (Apis mellifera L.)" PI.
Pat/70/. :27(1978)38-40.
USEPA. 2007. ECOTOXicology Database. Office of Research and Development National Health and Environmental Effects Research
Laboratory's (NHEERL's) Mid-Continent Ecology Division (MED), http://cfpub.epa.gov/ecotox/.
USEPA. 2009. "Risks of Paraquat Use to Federally Threatened California Red-legged Frog (Rana aurora draytonii). June 10, 2009.
USEPA. 2011. "EFED Registration Review: Preliminary Problem Formulation for Paraquat Dichloride." Environmental Fate and Effects
Division. Office of Chemical Safety and Pollution Prevention. U.S. Environmental Protection Agency. December 12, 2011 (DP
Barcode: 392076).
USEPA. 2012. "Response to Comments from Syngenta on Paraquat Dichloride Preliminary Problem Formulation." Environmental
Fate and Effects Division. Office of Chemical Safety and Pollution Prevention. U.S. Environmental Protection Agency. April 18, 2012
(DP Barcode: 399985).
USEPA. 2014. "Review of 6 Submitted Sediment Toxicity Study Protocols for Paraquat Dichloride and Review of 2 Submitted
Sediment Toxicity Studies." Environmental Fate and Effects Division. Office of Chemical Safety and Pollution Prevention. U.S.
Environmental Protection Agency. March 13, 2014 (DP Barcodes: 404036+).
Cited these from ECOTOX Database:
Banaee, M., et al. (2013). Histopathological Changes Induced by Paraquat on Some Tissues of Gourami Fish (Trichogaster
trichopterus). Open Vet. J. banaee@bkatu.ac.ir//Aquaculture Department, Natural Resource Faculty, Behbahan Khatam Alanbia
University of Technology, Behbahan, Iran//, AQUA. 3: 36-42. E172382.
Ghose, S. L., et al. (2014). Acute Toxicity Tests and meta-Analysis Identify Gaps in Tropical Ecotoxicology for Amphibians. Environ.
Toxicol. Chem.. AQUA. 33: 2114-2119 (Supplemental Journal Materials). E168034.
138
-------
Ha, M. H. and J. Choi (2009). Effects of Environmental Contaminants on Hemoglobin Gene Expression in Daphnia magna: A Potential
Biomarker for Freshwater Quality Monitoring. Arch. Environ. Contain. Toxicol.. AQUA. 57: 330-337. E118906.
Leboulanger, C., et al. (2009). Responses of Planktonic Microorganisms from Tropical Reservoirs to Paraquat and Deltamethrin
Exposure. Arch. Environ. Contain. Toxicol.. AQUA,MIXTURE. 56: 39-51. E112408.
139
-------
Appendix C. Example Aquatic Modeling Output
Below is an example output (MS cotton without sediment burial) summary file from a single
PWC modeling simulation.
Summary of Water Modeling of Paraquat and the USEPA Standard
Pond
Estimated Environmental Concentrations for Paraquat are presented in Table 1 for the USEPA
standard pond with the MScottonSTD field scenario. A graphical presentation of the year-to-
year peaks is presented in Figure 1. These values were generated with the Pesticide Water
Calculator (PWC), Version 1.52. Critical input values for the model are summarized in Tables 2
and 3.
This model estimates that about 7.5% of Paraquat applied to the field eventually reaches the
water body. The main mechanism of transport from the field to the water body is by erosion
(55.8% of the total transport), followed by runoff (27.4%) and spray drift (16.8%).
In the water body, pesticide dissipates with an effective water column half-life of
8022454000000.0 days. (This value does not include dissipation by transport to the benthic
region; it includes only processes that result in removal of pesticide from the complete system.)
In the benthic region, pesticide is stable. The vast majority of the pesticide in the benthic
region (99.96%) is sorbed to sediment rather than in the pore water.
Table 1. Estimated Environmental Concentrations (ppb) for Paraquat.
Peak (l-in-10 yr)
151.
4-day Avg (l-in-10 yr)
144.
21-day Avg (l-in-10 yr)
137.
60-day Avg (l-in-10 yr)
135.
365-day Avg (l-in-10 yr)
134.
Entire Simulation Mean
69.7
Table 2. Summary of Model Inputs for Paraquat.
Scenario
MScottonSTD
Cropped Area Fraction
1
Kd (ml/g)
le3
140
-------
Water Half-Life (days) @ 25 °C
0
Benthic Half-Life (days) @ 25 °C
0
Photolysis Half-Life (days) @ 40
°Lat
0
Hydrolysis Half-Life (days)
0
Soil Half-Life (days) @ 25 °C
0
Foliar Half-Life (days)
Molecular Weight
257.2
Vapor Pressure (torr)
le-9
Solubility (mg/l)
700000
Henry's Constant
0.0
Table 3. Application Schedule for Paraquat.
Date (Days Since
Emergence)
Type
Amount (kg/ha)
Eff.
Drift
-5
Foliar
1.13
.95
.125
2
Placed at a
depth of cm
1.13
.95
.125
9
T-band:top 2
cm fraction = ,
depth = cm
1.13
.95
.125
16
Ground
1.13
.95
.125
Figure 1. Yearly Peak Concentrations
141
-------
142
-------
Appendix D. Example Output for Terrestrial Modeling
Alfalfa and Clover (1.5 lb cation/acre, lx per crop cycle, interval not specified; modeled 3x annually with 120-day
interval):
TREX MODEL INPUTS
These values will be used in the calculation of exposure estimates for foliar, granular, liquid and/or seed
applications of pesticides.
Chemical Identity and Application Information
Chemical Name
Seed Treatment? (Check if yes)
Use:
Product name and form:
% A.I. (leading zero must be
entered for formulations <1%
a.i.):
Application Rate (lb ai/acre)
Half-life (days):
Application Interval (days):
Number of Applications:
Are you assessing applications
with variable rates or intervals?
Paraquat
Clover
Paraquat Cation
100.00%
1.5
35
120
3
no
Seeding Rate
(lbs/acre)
Assessed Species Inputs (optional, use defaults for RQs for national level
assessments) i
What body weight range is
assessed (grams)?
Birds
Mammals
Small
20
15
Medium
100
35
Large
1000
1000
143
-------
Endpoints
Avian
Endpoint Toxicity value
Indicate test
species below
LD50
(mg/kg-bw)
LC50
(mg/kg-
diet)
NOAEL
(mg/kg-bw)
NOAEC
(mg/kg-
diet)
26.50
698.00
29.40
Enter the Mineau et al. Scaling
Factor
1.15
Mammalian
Acute Study
Size (g) of mammal used in toxicity
study
Default rat body weight is 350
grams
Endpoint Toxicity value
LD50
(mg/kg-bw)
LC50
(mg/kg-diet)
Reported
Chronic
Endpoint
Is dietary
concent ratio
n (mg/kg-
diet)
reported
from the
available
chronic
mammal
study? (yes
or no)
Enter dietary
concent ratio
n (mg/kg-
diet)
93.00
7.50
yes
108.00
Chronic
Study
350
Reference
(MRID)
43685001
126783
NOTE
144
Optio
nal Opti
Test onal
Orga Test
nism Spec
Body ies
weig Nam Toxicity Value
ht (g) e Reference (MRID)
14.30
Zebr
a
Finch
49349901
43.00
Japa
nese
Quail
00022923 (got wt. from
CRLF TREX sheet)
110455
-------
Summary of Risk Quotient Calculations Based on Upper Bound Kenaga EECs
Table X. Upper Bound Kenaga, Acute Avian Dose-Based Risk Quotients
Size
Class
(gram
0
Adjust
ed
LD50
EECs and RQs
Short Grass
Tall Grass
Broadleaf Plants
Fruits/Pods/S
eeds
Arthropods
Granivore
EEC
RQ
EEC
RQ
EEC
RQ
EEC
RQ
EEC
RQ
EE
C
RQ
20
27.87
451.6
2
16.2
1
206.9
9
7.43
254.0
4
9.12
28.23
1.01
176.88
6.35
6.27
0.23
100
35.48
257.5
3
7.26
118.0
4
3.33
144.8
6
4.08
16.10
0.45
100.87
2.84
3.58
0.10
1000
50.11
115.3
0
2.30
52.85
1.05
64.86
1.29
7.21
0.14
45.16
0.90
1.60
0.03
Table X. Upper Bound Kenaga, Subacute Avian Dietary Based Risk Quotients
LC50
EECs and RQs
Short Grass
Tall Grass
Broadleaf
Plants
Fruits/Pods/Seeds
Arthropods
EEC
RQ
EE
C
RQ
EE
C
RQ
EEC
RQ
EE
C
RQ
698
396.54
0.57
181.
75
0.26
223.
05
0.32
24.78
0.04
155.
31
0.22
Size class not used for dietary risk quotients
Table X. Upper Bound Kenaga, Chronic Avian Dietary Based Risk Quotients
NOA
EC
(ppm)
EECs and RQs
Short Grass
Tall Grass
Broadleaf
Plants
Fruits/Pods/Seeds
Arthropods
EEC
RQ
EE
C
RQ
EE
C
RQ
EEC
RQ
EE
C
RQ
29
396.54
13.49
181.
75
6.18
223.
05
7.59
24.78
0.84
155.
31
5.28
Size class not used for dietary risk quotients
145
-------
Table X. Upper Bound Kenaga, Acute Mammalian Dose-Based Risk Quotients
Size
Class
(gram
0
Adjust
ed
LD50
EECs and RQs
Short Grass
Tall Grass
Broadleaf Plants
Fruits/Pods/S
eeds
Arthropods
Granivore
EEC
RQ
EEC
RQ
EEC
RQ
EEC
RQ
EEC
RQ
EE
C
RQ
15
204.40
378.0
7
1.85
173.2
8
0.85
212.6
6
1.04
23.63
0.12
148.0776
675
0.72
45
5.25
1
0.02
57
35
165.38
261.3
0
1.58
119.7
6
0.72
146.9
8
0.89
16.33
0.10
102.3414
784
0.61
88
3.62
91
0.02
19
1000
71.53
60.58
0.85
27.77
0.39
34.08
0.48
3.79
0.05
23.72823
056
0.33
17
0.84
14
0.01
18
Table X. Upper Bound Kenaga, Acute Mammalian Dietary Based Risk Quotients
LC50
(PPm)
EECs and RQs
Short Grass
Tall Grass
Broadleaf
Plants
Fruits/Pods/Seeds
Arthropods
EEC
RQ
EE
C
RQ
EE
C
RQ
EEC
RQ
EE
C
RQ
0
396.54
#DIV
/0!
181.
75
#DIV
/0!
223.
05
#DIV
/0!
24.78
#DIV/
0!
155.
31
#DIV/0!
Size class not used for dietary risk quotients
Table X. Upper Bound Kenaga, Chronic Mammalian Dietary Based Risk Quotients
NOA
EC
(ppm)
EECs and RQs
Short Grass
Tall Grass
Broadleaf
Plants
Fruits/Pods/Seeds/
Large Insects
Arthropods
EEC
RQ
EE
C
RQ
EE
C
RQ
EEC
RQ
EE
C
RQ
108
396.54
3.67
181.
75
1.68
223.
05
2.07
24.78
0.23
155.
31
1.44
Size class not used for dietary risk quotients
NOTE: The mammalian chronic RQ estimates are < values because the rat NOAEC used did not have an accompanying LOAEC.
Table X Upper Bound Kenaga, Chronic Mammalian Dose-Based Risk Quotients
Size
Class
(gram
s)
Adjust
ed
NOAE
L
EECs and RQs
Short Grass
Tall Grass
Broadleaf Plants
Fruits/Pods/S
eeds
Arthropods
Granivore
EEC
RQ
EEC
RQ
EEC
RQ
EEC
RQ
EEC
RQ
EE
C
RQ
15
16.48
378.0
7
22.9
4
173.2
8
10.5
1
212.6
6
12.90
23.63
1.43
148.08
8.98
5.25
0.32
35
13.34
261.3
0
19.5
9
119.7
6
8.98
146.9
8
11.02
16.33
1.22
102.34
7.67
3.63
0.27
1000
5.77
60.58
10.5
0
27.77
4.81
34.08
5.91
3.79
0.66
23.73
4.11
0.84
0.15
NOTE: The mammalian chronic RQ estimates are < values because the rat NOAEC used did not have an accompanying LOAEC.
146
-------
Using Mean Kenaga:
Table X. Mean Kenaga, Acute Avian Dose-Based Risk Quotients
Size
Class
(grams)
Adjusted
LD50
EECs and RQs
Short Grass
Tall Grass
Broadleaf
Plants
Fruits/Pods/
Seeds
Arthropods
Granivore
EEC
RQ
EEC
RQ
EEC
RQ
EEC
RQ
EEC
RQ
EEC
RQ
20
27.87
48.40
1.74
20.50
0.74
25.63
0.92
3.99
0.14
37.01
1.33
0.89
0.03
100
35.48
27.60
0.78
11.69
0.33
14.61
0.41
2.27
0.06
21.11
0.59
0.51
0.01
1000
50.11
12.36
0.25
5.23
0.10
6.54
0.13
1.02
0.02
9.45
0.19
0.23
0.00
Table X. Mean Kenaga, Subacute Avian Dietary Based Risk Quotients
LC50
EECs and RQs
Short Grass
Tall Grass
Broadleaf
Plants
Fruits/Pods/
Seeds
Arthropods
EEC
RQ
EEC
RQ
EEC
RQ
EEC
RQ
EEC
RQ
698
42.50
0.06
18.00
0.03
22.50
0.03
3.50
0.01
32.50
0.05
Size class not used for dietary risk quotients
Table X. Mean Kenaga, Chronic Avian Dietary Based Risk Quotients
NOAEC
(ppm)
EECs and RQs
Short Grass
Tall Grass
Broadleaf
Plants
Fruits/Pods/
Seeds
Arthropods
EEC
RQ
EEC
RQ
EEC
RQ
EEC
RQ
EEC
RQ
29
42.50
1.45
18.00
0.61
22.50
0.77
3.50
0.12
32.50
1.11
Size class not used for dietary risk quotients
Table X Mean Kenaga, Acute Mammalian Dose-Based Risk Quotients
Size
Class
(grams)
Adjust
ed
LD50
EECs and RQs
Short Grass
Tall Grass
Broadleaf
Plants
Fruits/Pods/
Seeds
Arthropods
Granivore
EEC
RQ
EEC
RQ
EEC
RQ
EEC
RQ
EEC
RQ
EEC
RQ
15
204.40
40.52
0.20
17.16
0.08
21.45
0.10
3.34
0.02
30.99
0.15
0.74
0.00
35
165.38
28.01
0.17
11.86
0.07
14.83
0.09
2.31
0.01
21.42
0.13
0.51
0.00
1000
71.53
6.49
0.09
2.75
0.04
3.44
0.05
0.53
0.01
4.97
0.07
0.12
0.00
Table X Mean Kenaga, Chronic Mammalian Dietary Based Risk Quotients
NOAEC
EECs and RQs
147
-------
(PPm)
Short Grass
Tall Grass
Broadleaf
Plants
Fruits/Pods/
Seeds/Large
Insects
Arthropods
EEC
RQ
EEC
RQ
EEC
RQ
EEC
RQ
EEC
RQ
108
42.50
0.39
18.00
0.17
22.50
0.21
3.50
0.03
32.50
0.30
Size class not used for dietary risk quotients
Table X. Mean Kenaga, Chronic Mammalian Dose-Based Risk Quotients
Size
Class
(grams
)
Adjusted
NOAEL
EECs and RQs
Short Grass
Tall Grass
Broadleaf Plants
Fruits/Pods/
Seeds
Arthropods
Granivore
EEC
RQ
EEC
RQ
EEC
RQ
EEC
RQ
EEC
RQ
EEC
RQ
15
16.48
40.52
2.46
17.16
1.04
21.45
1.30
3.34
0.20
30.99
1.88
0.74
0.04
35
13.34
28.01
2.10
11.86
0.89
14.83
1.11
2.31
0.17
21.42
1.61
0.51
0.04
1000
5.77
6.49
1.13
2.75
0.48
3.44
0.60
0.53
0.09
4.97
0.86
0.12
0.02
Based on Avian LOAEC:
NOAEC = 29.4
LOAEC = 101 mg cation/kg-diet
Avian
Indicate test species
Endpoint Toxicity value below
LD50 (mg/kg-bw)
LC50 (mg/kg-diet)
NOAEL (mg/kg-bw)
LOAEC (mg/kg-diet)
26.50
698.00
101.00
Based on Lowest Single App. Rate: 0.50 lb cation/A:
Table X. Upper Bound Kenaga, Chronic Avian Dietary Based Risk Quotients
NOAEC (ppm)
EECs and RQs
Short Grass
Tall Grass
Broadleaf
Plants
Fruits/Pods/Seeds
Arthropods
EEC
RQ
EEC
RQ
EEC
RQ
EEC
RQ
EEC
RQ
101
120.00
1.19
55.00
0.54
67.50
0.67
7.50
0.07
47.00
0.47
148
-------
Table X. Mean Kenaga, Chronic Avian Dietary Based Risk Quotients
NOAEC (ppm)
EECs and RQs
Short Grass
Tall Grass
Broadleaf
Plants
Fruits/Pods/Seeds
Arthropods
EEC
RQ
EEC
RQ
EEC
RQ
EEC
RQ
EEC
RQ
101
42.50
0.42
18.00
0.18
22.50
0.22
3.50
0.03
32.50
0.32
Based on Single App. at 1.01 lb cation/A:
Table X. Upper Bound Kenaga, Chronic Avian Dietary Based Risk Quotients
NOAEC (ppm)
EECs and RQs
Short Grass
Tall Grass
Broadleaf Plants
Fruits/Pods/Seeds
Arthropods
EEC
RQ
EEC
RQ
EEC
RQ
EEC
RQ
EEC
RQ
101
242.40
2.40
111.10
1.10
136.35
1.35
15.15
0.15
94.94
0.94
Table X. Mean Kenaga, Chronic Avian Dietary Based Risk Quotients
NOAEC (ppm)
EECs and RQs
Short Grass
Tall Grass
Broadleaf
Plants
Fruits/Pods/Seeds
Arthropods
EEC
RQ
EEC
RQ
EEC
RQ
EEC
RQ
EEC
RQ
101
85.85
0.85
36.36
0.36
45.45
0.45
7.07
0.07
65.65
0.65
Based on Highest Rates: 1.01 lb cation/A, 10 apps with 7-day intervals:
Table X. Upper Bound Kenaga, Chronic Avian Dietary Based Risk Quotients
NOAEC
(ppm)
EECs and RQs
Short Grass
Tall Grass
Broadleaf
Plants
Fruits/Pods/Seeds
Arthropods
EEC
RQ
EEC
RQ
EEC
RQ
EEC
RQ
EEC
RQ
101
1404.41
13.91
643.69
6.37
789.98
7.82
87.78
0.87
550.06
5.45
149
-------
Table X. Mean Kenaga, Chronic Avian Dietary Based Risk Quotients
NOAEC (ppm)
EECs and RQs
Short Grass
Tall Grass
Broadleaf
Plants
Fruits/Pods/Seeds
Arthropods
EEC
RQ
EEC
RQ
EEC
RQ
EEC
RQ
EEC
RQ
101
497.39
4.92
210.66
2.09
263.33
2.61
40.96
0.41
380.36
3.77
TREX Runs Using the Additional Line-of-Evidence for Mammals - PreNatal Growth Endpoint:
TREX MODEL INPUTS
These values will be used in the calculation of exposure estimates for foliar, granular, liquid and/or
seed applications of pesticides.
Chemical Identity and Application Information
Chemical Name:
Seed Treatment? (Check if yes)
Use:
Product name and form:
% A.I. (leading zero must be entered for
formulations <1% a.i.):
Application Rate (lb ai/acre)
Half-life (days):
Application Interval (days):
Number of Applications:
Are you assessing applications with
variable rates or intervals?
Paraquat
Alfalfa/Clover
Paraquat Cation
100.00%
1.5
35
120
no
Mammalian
Acute Study
Chronic Study
Size (g) of mammal used in toxicity study
Default rat body weight is 350 grams
350
350
Endpoint
LD50 (mg/kg-bw)
LC50 (mg/kg-diet)
Reported Chronic
Endpoint
Toxicity value
93.00
1.00
Reference (MRID)
43685001
113714
150
-------
Is dietary concentration
(mg/kg-diet) reported from
the available chronic
mammal study? (yes or no)
Estimated Chronic Diet
Concentration Equivalent mg/kg-diet based on
to Reported Chronic Daily standard FDA lab rat
Dose conversion
Summary of Risk Quotient Calculations Based on Upper Bound Kenaga EECs
Table X. Upper Bound Kenaga, Chronic Mammalian Dietary Based Risk Quotients
NOAE
C
(PPm)
EECs and RQs
Short Grass
Tall Grass
Broadleaf
Plants
Fruits/Pods/Seeds/La
rge Insects
Arthropods
EEC
RQ
EEC
RQ
EEC
RQ
EEC
RQ
EEC
RQ
20
396.54
19.83
181.7
5
9.09
223.0
5
11.15
24.78
1.24
155.31
7.77
Size class not used for dietary risk quotients
Table X. Upper Bound Kenaga, Chronic Mammalian Dose-Based Risk Quotients
Size
Class
(grams
)
Adjust
ed
NOAE
L
EECs and RQs
Short Grass
Tall Grass
Broadleaf Plants
Fruits/Pods/See
ds
Arthropods
Granivore
EEC
RQ
EEC
RQ
EEC
RQ
EEC
RQ
EEC
RQ
EE
C
R
Q
15
2.20
378.0
7
172.0
2
173.2
8
78.84
212.6
6
96.76
23.63
10.75
148.0
8
67.3
7
5.25
2.3
9
35
1.78
261.3
0
146.9
4
119.7
6
67.35
146.9
8
82.65
16.33
9.18
102.3
4
57.5
5
3.63
2.0
4
1000
0.77
60.58
78.76
27.77
36.10
34.08
44.31
3.79
4.92
23.73
30.8
5
0.84
1.0
9
151
-------
Summary of Risk Quotient Calculations Based on Mean Kenaga EECs
Table X. Mean Kenaga, Chronic Mammalian Dietary Based Risk Quotients
NOAE
C
(PPm)
EECs and RQs
Short Grass
Tall Grass
Broadleaf
Plants
Fruits/Pods/Seeds/La
rge Insects
Arthropods
EEC
RQ
EE
C
RQ
EE
C
RQ
EEC
RQ
EEC
RQ
20
140.44
7.02
59.4
8
2.97
74.3
5
3.72
11.57
0.58
107.40
5.37
Size class not used for dietary risk quotients
Table X. Mean Kenaga, Chronic Mammalian Dose-Based Risk Quotients
Size
Class
(grams
)
Adjuste
d
NOAE
L
EECs and RQs
Short Grass
Tall Grass
Broadleaf Plants
Fruits/Pods/See
ds
Arthropods
Granivore
EEC
RQ
EE
C
RQ
EE
C
RQ
EEC
RQ
EEC
RQ
EE
C
RQ
15
2.20
133.9
0
60.9
2
56.7
1
25.8
0
70.8
9
32.25
11.03
5.02
102.3
9
46.5
9
2.45
1.1
1
35
1.78
92.54
52.0
4
39.1
9
22.0
4
48.9
9
27.55
7.62
4.29
70.77
39.8
0
1.69
0.9
5
1000
0.77
21.46
27.9
0
9.09
11.8
1
11.3
6
14.77
1.77
2.30
16.41
21.3
3
0.39
0.5
1
Mean Kenega:
Dose-based RQs (Dose-
based EEC/LD50 or NOAEL)
Small mammal
15 grams
Medium mammal
35 grams
Large mammal
1000 grams
Acute
Chronic
Acute
Chronic
Acute
Chronic
Short Grass
0.66
60.92
0.56
52.04
0.30
27.90
Tall Grass
0.28
25.80
0.24
22.04
0.13
11.81
Broadleaf plants
0.35
32.25
0.30
27.55
0.16
14.77
Fruits/pods
0.05
5.02
0.05
4.29
0.02
2.30
Arthropods
0.50
46.59
0.43
39.80
0.23
21.33
Seeds
0.01
1.11
0.01
0.95
0.01
0.51
Chemical Identity and Application Information
Chemical Name:
Paraquat
"
Seed Treatment? (Check if yes)
Use:
Product name and form:
Premeses/Areas
Paraquat Cation
152
-------
% A.I. (leading zero must be entered for formulations
<1% a.i.):
Application Rate (lb ai/acre)
Half-life (days):
Application Interval (days):
Number of Applications:
Are you assessing applications with variable rates or
intervals?
100.00%
1.01
35
10
no
Summary of Risk Quotient Calculations Based on Upper Bound Kenaga EECs
Table X. Upper Bound Kenaga, Chronic Mammalian Dietary Based Risk Quotients
NOAE
C
(PPm)
EECs and RQs
Short Grass
Tall Grass
Broadleaf
Plants
Fruits/Pods/Seeds/L
arge Insects
Arthropods
EEC
RQ
EEC
RQ
EEC
RQ
EEC
RQ
EEC
RQ
20
1404.4
1
70.22
643.6
9
32.18
789.9
8
39.50
87.78
4.39
550.06
27.50
Size class not used for dietary risk quotients
Table X. Upper Bound Kenaga, Chronic Mammalian Dose-Based Risk Quotients
Size
Class
(grams
)
Adjust
ed
NOAE
L
EECs and RQs
Short Grass
Tall Grass
Broadleaf Plants
Fruits/Pods/See
ds
Arthropods
Granivore
EEC
RQ
EEC
RQ
EEC
RQ
EEC
RQ
EEC
RQ
EE
C
R
Q
15
2.20
1339.
00
609.2
4
613.7
1
279.2
3
753.1
9
342.70
83.69
38.08
524.4
4
238.6
2
18.6
0
8.4
6
35
1.78
925.4
3
520.4
1
424.1
5
238.5
2
520.5
5
292.73
57.84
32.53
362.4
6
203.8
3
12.8
5
7.2
3
1000
0.77
214.5
6
278.9
6
98.34
127.8
6
120.6
9
156.91
13.41
17.43
84.04
109.2
6
2.98
3.8
7
Table X. Mean Kenaga, Chronic Mammalian Dietary Based Risk Quotients
NOAE
C
(PPm)
EECs and RQs
Short Grass
Tall Grass
Broadleaf
Plants
Fruits/Pods/Seeds/L
arge Insects
Arthropods
EEC
RQ
EEC
RQ
EEC
RQ
EEC
RQ
EEC
RQ
20
497.39
24.87
210.6
6
10.53
263.3
3
13.17
40.96
2.05
380.36
19.02
Size class not used for dietary risk quotients
153
-------
Table X. Mean Kenaga, Chronic Mammalian Dose-Based Risk Quotients
Size
Class
(grams
)
Adjust
ed
NOAE
L
EECs and RQs
Short Grass
Tall Grass
Broadleaf Plants
Fruits/Pods/See
ds
Arthropods
Granivor
e
EEC
RQ
EEC
RQ
EEC
RQ
EEC
RQ
EEC
RQ
EE
C
R
Q
15
2.20
474.2
3
215.7
7
200.8
5
91.39
251.0
6
114.23
39.0
5
17.77
362.6
4
165.0
0
¦ OO
00
3.9
5
35
1.78
327.7
6
184.3
1
138.8
1
78.06
173.5
2
97.58
26.9
9
15.18
250.6
4
140.9
4
6.0
0
3.3
7
1000
0.77
75.99
98.80
32.18
41.84
40.23
52.30
6.26
8.14
58.11
75.55
1.3
9
1.8
1
Dose-based RQs (Dose-
based EEC/LD50 or NOAEL)
Small mammal
15 grams
Medium mammal
35 grams
Large mammal
1000 grams
Acute
Chronic
Acute
Chronic
Acute
Chronic
Short Grass
2.32
215.77
1.98
184.31
1.06
98.80
Tall Grass
0.98
91.39
0.84
78.06
0.45
41.84
Broadleaf plants
1.23
114.23
1.05
97.58
0.56
52.30
Fruits/pods
0.19
17.77
0.16
15.18
0.09
8.14
Arthropods
1.77
165.00
1.52
140.94
0.81
75.55
Seeds
0.04
3.95
0.04
3.37
0.02
1.81
154
-------
Chemical Identity and Application Information
Chemical Name:
Paraquat
Seed Treatment? (Check if yes)
Use:
Product name and form:
% A.I. (leading zero must be entered for formulations
<1% a.i.):
Application Rate (lb ai/acre)
Half-life (days):
Application Interval (days):
Number of Applications:
Multi Ag and Non-Ag
Paraquat Cation
100.00%
1.01
35
7
5
Are you assessing applications with variable rates or
intervals?
no
Table X. Upper Bound Kenaga, Chronic Mammalian Dietary Based Risk Quotients
NOAE
C
(PPm)
EECs and RQs
Short Grass
Tall Grass
Broadleaf
Plants
Fruits/Pods/Seeds/L
arge Insects
Arthropods
EEC
RQ
EEC
RQ
EEC
RQ
EEC
RQ
EEC
RQ
20
936.27
46.81
429.1
3
21.46
526.6
5
26.33
58.52
2.93
366.71
18.34
Size class not used for dietary risk quotients
Table X. Upper Bound Kenaga, Chronic Mammalian Dose-Based Risk Quotients
Size
Class
(grams
)
Adjust
ed
NOAE
L
EECs and RQs
Short Grass
Tall Grass
Broadleaf Plants
Fruits/Pods/Seed
s
Arthropods
Granivore
EEC
RQ
EEC
RQ
EEC
RQ
EEC
RQ
EEC
RQ
EE
C
R
Q
15
2.20
892.6
6
406.1
6
409.1
4
186.1
6
502.1
2
228.46
55.79
25.38
349.6
3
159.0
8
12.4
0
5.6
4
35
1.78
616.9
5
346.9
4
282.7
7
159.0
1
347.0
3
195.15
38.56
21.68
241.6
4
135.8
8
8.57
4.8
2
1000
0.77
143.0
4
185.9
7
65.56
85.24
80.46
104.61
8.94
11.62
56.02
72.84
1.99
2.5
8
155
-------
Summary of Risk Quotient Calculations Based on Mean Kenaga EECs
Table X. Mean Kenaga, Chronic Mammalian Dietary Based Risk Quotients
NOAE
C
(PPm)
EECs and RQs
Short Grass
Tall Grass
Broadleaf
Plants
Fruits/Pods/Seeds/L
arge Insects
Arthropods
EEC
RQ
EEC
RQ
EEC
RQ
EEC
RQ
EEC
RQ
20
331.60
16.58
140.4
4
7.02
175.5
5
8.78
27.31
1.37
253.57
12.68
Size class not used for dietary risk quotients
Table X. Mean Kenaga, Chronic Mammalian Dose-Based Risk Quotients
Size
Class
(grams
)
Adjust
ed
NOAE
L
EECs and RQs
Short Grass
Tall Grass
Broadleaf Plants
Fruits/Pods/See
ds
Arthropods
Granivor
e
EEC
RQ
EEC
RQ
EEC
RQ
EEC
RQ
EEC
RQ
EE
C
R
Q
15
2.20
316.1
5
143.8
5
133.9
0
60.92
167.3
7
76.15
26.0
4
11.85
241.7
6
110.0
0
5.7
9
2.6
3
35
1.78
218.5
0
122.8
7
92.54
52.04
115.6
8
65.05
17.9
9
10.12
167.0
9
93.96
4.0
0
2.2
5
1000
0.77
50.66
65.87
21.46
27.90
26.82
34.87
4.17
5.42
38.74
50.37
0.9
3
1.2
1
Dose-based RQs (Dose-
based EEC/LD50 or NOAEL)
Small mammal
15 grams
Medium mammal
35 grams
Large mammal
1000 grams
Acute
Chronic
Acute
Chronic
Acute
Chronic
Short Grass
1.55
143.85
1.32
122.87
0.71
65.87
Tall Grass
0.66
60.92
0.56
52.04
0.30
27.90
Broadleaf plants
0.82
76.15
0.70
65.05
0.37
34.87
Fruits/pods
0.13
11.85
0.11
10.12
0.06
5.42
Arthropods
1.18
110.00
1.01
93.96
0.54
50.37
Seeds
0.03
2.63
0.02
2.25
0.01
1.21
156
-------
Chemical Identity and Application Information
Chemical Name:
Seed Treatment? (Check if yes)
Use:
Product name and form:
% A.I. (leading zero must be entered for formulations
<1% a.i.):
Application Rate (lb ai/acre)
Half-life (days):
Application Interval (days):
Number of Applications:
Paraquat
.........
Ag and Non-Ag Single App
Paraquat Cation
100.00%
1.01
35
1
Are you assessing applications with variable rates or
intervals?
no
Summary of Risk Quotient Calculations Based on Upper Bound Kenaga EECs
Table X. Upper Bound Kenaga, Chronic Mammalian Dietary Based Risk Quotients
NOAE
C
(PPm)
EECs and RQs
Short Grass
Tall Grass
Broadleaf
Plants
Fruits/Pods/Seeds/La
rge Insects
Arthropods
EEC
RQ
EEC
RQ
EEC
RQ
EEC
RQ
EEC
RQ
20
242.40
12.12
111.1
0
5.56
136.3
5
6.82
15.15
0.76
94.94
4.75
Size class not used for dietary risk quotients
Table X. Upper Bound Kenaga, Chronic Mammalian Dose-Based Risk Quotients
Size
Class
(grams
)
Adjust
ed
NOAE
L
EECs and RQs
Short Grass
Tall Grass
Broadleaf Plants
Fruits/Pods/Seed
s
Arthropods
Granivore
EEC
RQ
EEC
RQ
EEC
RQ
EEC
RQ
EE
C
RQ
EE
C
RQ
15
2.20
231.1
1
105.1
5
105.9
3
48.20
130.0
0
59.15
14.44
6.57
90.5
2
41.1
9
3.21
1.4
6
35
1.78
159.7
3
89.82
73.21
41.17
89.85
50.52
9.98
5.61
62.5
6
35.1
8
2.22
1.2
5
1000
0.77
37.03
48.15
16.97
22.07
20.83
27.08
2.31
3.01
14.5
0
18.8
6
0.51
0.6
7
157
-------
Summary of Risk Quotient Calculations Based on Mean Kenaga EECs
Table X. Mean Kenaga, Chronic Mammalian Dietary Based Risk Quotients
NOAE
C
(PPm)
EECs and RQs
Short Grass
Tall Grass
Broadleaf
Plants
Fruits/Pods/Seeds/Lar
ge Insects
Arthropods
EEC
RQ
EE
C
RQ
EE
C
RQ
EEC
RQ
EEC
RQ
20
85.85
4.29
36.3
6
1.82
45.4
5
2.27
7.07
0.35
65.65
3.28
Size class not used for dietary risk quotients
Table X. Mean Kenaga, Chronic Mammalian Dose-Based Risk Quotients
Size
Class
(grams
)
Adjuste
d
NOAE
L
EECs and RQs
Short Grass
Tall Grass
Broadleaf Plants
Fruits/Pods/Seed
s
Arthropods
Granivore
EE
C
RQ
EE
C
RQ
EE
C
RQ
EEC
RQ
EE
C
RQ
EE
C
RQ
15
2.20
81.8
5
37.2
4
34.6
7
15.7
7
43.3
3
19.72
6.74
3.07
62.5
9
28.4
8
1.50
0.6
8
35
1.78
56.5
7
31.8
1
23.9
6
13.4
7
29.9
5
16.84
4.66
2.62
43.2
6
24.3
3
1.04
0.5
8
1000
0.77
13.1
2
17.0
5
5.56
7.22
6.94
9.03
1.08
1.40
10.0
3
13.0
4
0.24
0.3
1
Dose-based RQs (Dose-
based EEC/LD50 or NOAEL)
Small mammal
15 grams
Medium mammal
35 grams
Large mammal
1000 grams
Acute
Chronic
Acute
Chronic
Acute
Chronic
Short Grass
0.40
37.24
0.34
31.81
0.18
17.05
Tall Grass
0.17
15.77
0.14
13.47
0.08
7.22
Broadleaf plants
0.21
19.72
0.18
16.84
0.10
9.03
Fruits/pods
0.03
3.07
0.03
2.62
0.02
1.40
Arthropods
0.31
28.48
0.26
24.33
0.14
13.04
Seeds
0.01
0.68
0.01
0.58
0.00
0.31
158
-------
Chemical Identity and Application Information
Chemical Name:
Seed Treatment? (Check if yes)
Use:
Product name and form:
% A.I. (leading zero must be entered for formulations
<1% a.i.):
Application Rate (lb ai/acre)
Half-life (days):
Application Interval (days):
Number of Applications:
Paraquat
I...*.—...—
Ag and Non-Ag Lower Rate
Paraquat Cation
100.00%
0.5
35
1
Are you assessing applications with variable rates or
intervals?
no
Summary of Risk Quotient Calculations Based on Upper Bound Kenaga EECs
Table X. Upper Bound Kenaga, Chronic Mammalian Dietary Based Risk Quotients
NOAE
C
(PPm)
EECs and RQs
Short Grass
Tall Grass
Broadleaf
Plants
Fruits/Pods/Seeds/La
rge Insects
Arthropods
EEC
RQ
EEC
RQ
EEC
RQ
EEC
RQ
EEC
RQ
20
120.00
6.00
55.0
0
2.75
67.5
0
3.38
7.50
0.38
47.00
2.35
Size class not used for dietary risk quotients
Table X. Upper Bound Kenaga, Chronic Mammalian Dose-Based Risk Quotients
Size
Class
(grams
)
Adjuste
d
NOAE
L
EECs and RQs
Short Grass
Tall Grass
Broadleaf Plants
Fruits/Pods/Seeds
Arthropods
Granivor
e
EEC
RQ
EEC
RQ
EEC
RQ
EEC
RQ
EEC
RQ
EE
C
R
Q
15
2.20
114.4
1
52.0
6
52.4
4
23.8
6
64.3
6
29.28
7.15
3.25
44.8
1
20.3
9
1.5
9
0.7
2
35
1.78
79.07
44.4
7
36.2
4
20.3
8
44.4
8
25.01
4.94
2.78
30.9
7
17.4
2
1.1
0
0.6
2
1000
0.77
18.33
23.8
4
8.40
10.9
2
10.3
1
13.41
1.15
1.49
7.18
9.34
0.2
5
0.3
3
159
-------
Summary of Risk Quotient Calculations Based on Mean Kenaga EECs
Table X. Mean Kenaga, Chronic Mammalian Dietary Based Risk Quotients
NOAE
C
(PPm)
EECs and RQs
Short Grass
Tall Grass
Broadleaf
Plants
Fruits/Pods/Seeds/La
rge Insects
Arthropods
EEC
RQ
EEC
RQ
EEC
RQ
EEC
RQ
EEC
RQ
20
42.50
2.13
18.0
0
0.90
22.5
0
1.13
3.50
0.18
32.50
1.63
Size class not used for dietary risk quotients
Table X. Mean Kenaga, Chronic Mammalian Dose-Based Risk Quotients
Size
Class
(grams
)
Adjuste
d
NOAE
L
EECs and RQs
Short Grass
Tall Grass
Broadleaf Plants
Fruits/Pods/See
ds
Arthropods
Granivore
EE
C
RQ
EEC
RQ
EEC
RQ
EEC
RQ
EEC
RQ
EE
C
R
Q
15
2.20
40.5
2
18.4
4
17.1
6
7.81
21.4
5
9.76
3.34
1.52
30.9
9
14.1
0
0.74
0.3
4
35
1.78
28.0
1
15.7
5
11.8
6
6.67
14.8
3
8.34
2.31
1.30
21.4
2
12.0
4
0.51
0.2
9
1000
0.77
6.49
8.44
2.75
3.58
3.44
4.47
0.53
0.70
4.97
6.46
0.12
0.1
5
Dose-based RQs (Dose-
based EEC/LD50 or NOAEL)
Small mammal
15 grams
Medium mammal
35 grams
Large mammal
1000 grams
Acute
Chronic
Acute
Chronic
Acute
Chronic
Short Grass
0.20
18.44
0.17
15.75
0.09
8.44
Tall Grass
0.08
7.81
0.07
6.67
0.04
3.58
Broadleaf plants
0.10
9.76
0.09
8.34
0.05
4.47
Fruits/pods
0.02
1.52
0.01
1.30
0.01
0.70
Arthropods
0.15
14.10
0.13
12.04
0.07
6.46
Seeds
0.00
0.34
0.00
0.29
0.00
0.15
160
-------
TerrPlant v. 1.2.2
Green values signify user inputs (Tables 1, 2 and 4).
Input and output guidance is in popups indicated by red arrows.
Table 1. Chemical Identity
u
Chemical Name
Paraquat
PC code
61601
Use
Alfalfa and Clover
Application Method
Aerial
Application Form
Spray
Solubility in Water
(PPm)
336,000
Table 2. Input parameters used to derive EECs.
Input Parameter
Symbol
Value
Units
Application Rate
A
1.5
y
Incorporation
I
1
none
Runoff Fraction
R
0.05
none
Drift Fraction
D
0.05
none
Table 3. EECs for Paraquat. Units in y.
Description
Equation
EEC
Runoff to dry areas
(A/I)*R
0.075
Runoff to semi-aquatic areas
(A/I)*R*10
0.75
Spray drift
A*D
0.075
Total for dry areas
((A/I)*R)+(A*D)
0.15
Total for semi-aquatic areas
((A/I)*R*10)+(A*D)
0.825
Table 4. Plant survival and growth data used for RQ derivation. Units are in y.
Plant type
Seedling E
EC25
Emergence
NOAEC
Vegetati
EC25
ve Vigor
NOAEC
Monocot
0.635
0.28
0.0208
0.018
Dicot
0.67
0.171
0.0217
0.0048
Table 5. RQ values for plants in dry and semi-aquatic areas exposed to Paraquat through runoff
and/or spray drift*
Plant Type
Listed Status
Dry
Semi-Aquatic
Spray Drift
Monocot
non-listed
0.24
1.30
3.61
Monocot
listed
0.54
2.95
4.17
Dicot
non-listed
0.22
1.23
3.46
Dicot
listed
0.88
4.82
15.63
*lf RQ > 1.0, the LOC is exceeded, resulting in potential for risk to that plant group.
161
-------
BeeRex Output:
Table 1. User inputs (related to exposure)
Description
Value
Application rate
1.5
Units of app rate
lb a.i./A
Application method
foliar spray
Are empirical residue data available?
no
Table 5. Results (highest
RQs)
Exposure
Adults
Larvae
Acute contact
0.077885
NA
Acute dietary
2.19
#DIV/0
!
Chronic dietary
#DI V/0!
#DIV/0
!
a.i./mg
a.i./mg
a.i./mg
Table 2. Toxicity data
Description
Value (|jg
a.i./bee)
Adult contact LD50
52
Adult oral LD50
22
Adult oral NOAEL
Larval LD50
Larval NOAEL
Table 3. Estimated concentrations in pollen and nectar
Application method
EECs (mg a.i./kg)
EECs(ng
a.i./mg)
foliar spray
165
0.165
soil application
NA
NA
seed treatment
NA
NA
tree trunk
NA
NA
Table 4. Daily consumption of food, pesticide dose and resulting
dietary RQs for all bees
Life stage
Caste or task in hive
Average age
(in days)
Jelly
(mg/day
)
Nectar
(mg/day
)
Pollen
(mg/d
ay)
Total dose
(^g
a.i./bee)
Acute
RQ
Larval
Worker
1
1.9
0
0
0.003135
#DIV/0!
162
-------
2
9.4
0
0
0.01551
#DIV/0!
3
19
0
0
0.03135
#DIV/0!
4
0
60
1.8
10.197
#DIV/0!
5
0
120
3.6
20.394
#DIV/0!
Drone
6+
0
130
3.6
22.044
#DIV/0!
Queen
1
1.9
0
0
0.003135
#DIV/0!
2
9.4
0
0
0.01551
#DIV/0!
3
23
0
0
0.03795
#DIV/0!
4+
141
0
0
0.23265
#DIV/0!
Adult
Worker (cell cleaning
and capping)
0-10
0
60
6.65
10.99725
0.49987
5
Worker (brood and
queen tending, nurse
bees)
6 to 17
0
140
9.6
24.684
1.122
Worker (comb
building, cleaning
and food handling)
11 to 18
0
60
1.7
10.1805
0.46275
Worker (foraging for
pollen)
>18
0
43.5
0.041
7.184265
0.32655
75
Worker (foraging for
nectar)
>18
0
292
0.041
48.186765
2.19030
75
Worker
(maintenance of hive
in winter)
0-90
0
29
2
5.115
0.2325
Drone
>10
0
235
0.0002
38.775033
1.76250
15
Queen (laying 1500
eggs/day)
Entire lifestage
525
0
0
0.86625
0.03937
5
163
-------
AgDrift Output:
Aerial Applications:
Fine Droplets:
-------
Appendix E. Incident Report Outputs
Aggregate Incident Reports-PC Codes 061601 (Paraquat Dichloride) and 061603 (Paraquat):
165
-------
166
-------
167
-------
IDS Output Table for Incidents from 1975 to June 2018
Incident Stat Certainity
Number Year e Product Legality Index
B0000502-18
1000097-015
1000097-015
1000097-015
1007334-001
1007371-008
1007371-033
1007371-034
1008168-001
1009314-005
1009314-005
1009314-005
1009573-009
1011838-038
1011838-038
1011838-055
1011838-091
1011838-091
1012366-023
1012684-010
Year
1981 VA
1989 VA
1989 VA
1989 VA
1998 IL
1997 PA
1997 PA
1997 PA
1998 VA
1997 IN
1997 IN
1997 IN
1999 AL
2001 GA
2001 GA
Product
N/R
N/R
N/R
GRAMOXOME
GRAMOXONE
GRAMOXONE
GRAMOXONE
GRAMOXONE
EXTRA
GRAMOXONE
EXTRA
GRAMOXONE
EXTRA
GRAMOXONE
EXTRA
GRAMOXONE
GRAMOXONE
GRAMOXONE
2001 NC Gramoxone
2001 OK Cyclone
2001 OK Cyclone
2000 VA
2001 VA
Gramoxone
Gramoxone
Legality
Undetermin
ed
Undetermin
ed
Undetermin
ed
Undetermin
ed
Undetermin
ed
Misuse
(accidental)
Misuse
(accidental)
Misuse
(accidental)
Registered
Use
Registered
Use
Registered
Use
Registered
Use
Undetermin
ed
Undetermin
ed
Undetermin
ed
Registered
Use
Undetermin
ed
Undetermin
ed
Undetermin
ed
Registered
Possible
Unlikely
Unlikely
Unlikely
Possible
Highly
Probable
Probable
Probable
Probable
Possible
Possible
Possible
Possible
Possible
Possible
Possible
Possible
Possible
Possible
Possible
Use Site
Agricultural
Area
N/R
N/R
N/R
N/R
Soybean
CORN
CORN
Corn
FIELD
FIELD
FIELD
N/R
Peanut
Peanut
N/R
Peanut
Peanut
Corn, field
Peanut
168
Species
Sunfish
Chipping
Sparrow
Common
Grackle
American
Robin
Corn
Soybean
Grass
Grass
Canada Goose
Bluegill
Crappie
Bass
Corn
Peanut
Peanut
Peanut
Peanut
Peanut
Corn, Field
Peanut
Scientific Name
Centrarchidae
Spizella passerina
Quiscalus quiscula
Turdus
migratorius
Zea mays
Glycine max
Poaceae
Poaceae
Branta canadensis
Lepomis
macrochirus
Pomoxis sp.
Micropterus spp.
Zea mays
Arachis hypogaea
Arachis hypogaea
Arachis hypogaea
Arachis hypogaea
Arachis hypogaea
Zea mays
Arachis hypogaea
Distance
ADJACENT
Vicinity
Vicinity
Vicinity
Vicinity
VICINITY
VICINITY
VICINITY
10 feet from
creek
250 FEET
250 FEET
250 FEET
Treated directly
Treated directly
Treated directly
N/R
Affected Magnitude
53 53
1 1
1 1
At least 2
18 of 103 acres
UNKNOWN
UNKNOWN
UNKNOWN
5 5
75% OF 200
ACRES
ALL 25 ACRES
ALL 25 ACRES
10 acres
80 acres
80 acres
120 acres
5 acres
-------
Use
1012684-010
1013554-040
1013636-029
1013884-014
1013884-038
1014034-009
1014034-009
1014409-001
1014409-001
1014409-024
1014409-024
1016940-005
1020459-025
1020459-025
1020627-019
1020627-019
1020627-033
1020627-036
1020627-036
1020998-023
1021276-006
2001
2002
1996
1998
1998
2003
2003
1992
1992
1992
1992
2005
2000
2000
2001
2001
2001
2001
2001
2002
VA
IL
OR
WA
WA
GA
GA
WA
WA
WA
WA
CA
WA
WA
WA
WA
WA
WA
WA
WA
Gramoxone
Gramoxone Max
Gramoxone
Gramoxone MAX
Gramoxone MAX
Gramoxone
2004 WA
Registered
Use
Misuse
Registered
Use
Undetermin
ed
Registered
Use
Registered
Use
Registered
Use
Undetermin
ed
Undetermin
ed
Misuse
Misuse
Misuse
(intentional)
Undetermin
ed
Undetermin
ed
Undetermin
ed
Undetermin
ed
Undetermin
ed
Undetermin
ed
Undetermin
ed
Misuse
Undetermin
ed
Possible
Probable
Possible
Possible
Probable
Possible
Possible
Possible
Possible
Possible
Possible
Probable
Probable
Probable
Probable
Probable
Probable
Probable
Probable
Possible
Probable
Peanut
N/R
N/R
Potato ?
Pea
Pasture
Pasture
N/R
N/R
Wheat
Wheat
Wheat
Corn, sweet
Corn, sweet
Agricultural
area
Agricultural
area
Agricultural
area
Agricultural
area
Agricultural
area
Agricultural
area
169
Peanut
Corn, Field
Peppermint
Apple
Ornamental
Pasture Grass
Pasture Grass
Radish
Radish
Alfalfa
Alfalfa
Wheat
Winter Wheat
Winter Wheat
Blueberry
Blueberry
Dog
Alfalfa
Alfalfa
Cherry
Corn
Arachis hypogaea
Zea mays
Mentha x
piperita
Malus
domestica
Raphanus
sativus
Raphanus
sativus
Medicago sativa
Medicago sativa
Triticum sp.
Vaccinium sp.
Vaccinium sp.
Canis familiaris
Medicago sativa
Medicago sativa
Prunus sp.
Zea mays
On site
Treated directly
Vicinity
Vicinity
Treated directly
Treated directly
Vicinity
Vicinity
Vicinity
Vicinity
Adjacent
Adjacent
Adjacent
Adjacent
Adjacent
5 acres
1040 acres
181 acres
Not given
Not given
60 acres
60 acres
Not given
Not given
Not given
Not given
120 of 184
acres
2.5 acres
2.5 acres
Vicinity
-------
1021457-015
1021457-015
1021685-002
1021685-002
1021685-002
1021685-002
1021848-003
1023444-012
1023587-006
1023587-006
1027242-001
1028934-
00016
1029512-
00004
2006 WA
2006 WA
2009
2009
2009
2009
2010
2011 PA
2011 CA
2011 CA
2016 CA
2016
Gramoxone Inteon
Gramoxone Inteon
Gramoxone Inteon
Undetermin
ed
Undetermin
ed
Undetermin
ed
Undetermin
ed
Undetermin
ed
Undetermin
ed
Undetermin
ed
Undetermin
ed
Undetermin
ed
Undetermin
ed
Undetermin
GRAMOXONE SL 2.0 ed
Undetermin
GRAMOXONE SL 2.0 ed
Possible
Possible
Probable
Probable
Probable
Probable
Possible
Possible
Possible
Possible
Possible
Possible
Possible
N/R
N/R
Bait,
carcass/meat
Bait,
carcass/meat
Bait,
carcass/meat
Bait,
carcass/meat
Bait,
carcass/meat
Corn, field
Cotton
Cotton
Agricultural
area
Ornamental
Ornamental
Eagle
Golden Eagle
Eagle
Golden Eagle
Eagle
Corn
Vegetable
Vegetable
Dog
Onion
Honey Bee
Adjacent
Adjacent
many
many
Buteoninae
Aquila
chrysaetos
Buteoninae
Aquila
chrysaetos
Buteoninae
Zea mays
Canis familiaris
Allium cepa
Apis mellifera
N/R
On site
Vicinity
Vicinity
Vicinity
Vicinity
N/R
13 13
100% of 130
acres
100% of 25
acres
100% of 25
acres
145 145 acres
2 2 hives
170
-------
Information on New Incidents and Others Not Previously Summarized
New Incidents Not Previously Summarized
1021685-002 UNDETERMINED LEGALITY
02/18/2009 Ireland Probable Likelihood
This incident involves the death of a young golden eagle in Dunlewy, Ireland. Toxicity tests showed that the cause
of death was paraquat poisoning, despite paraquat being banned in the EU in 2007 for marketing and use as a
pesticide. The bird had been dead for some time when found.
1021848-003 UNDETERMINED LEGALITY
05/08/2010 Ireland Possible Likelihood
This incident involves the deaths of thirteen sea eagles in Kerry, Ireland since their release in Killarney National
Park in 2007. The eagles were killed by different poisons, sometimes in cocktail form, laced into pieces of meat or
animal carcasses. Paraquat and carbofuran were each identified in at least one body by a lab examination.
Paraquat is banned in the EU.
1021848-004 UNDETERMINED LEGALITY
November 2007 - May 2010 Ireland Possible Likelihood
This incident involves the death of 1-4 red-kites in Wicklow, Ireland following a re-introduction program. The birds
were killed by different poisons, including paraquat and carbofuran, in cocktail form laced into pieces of meat or
animal carcasses. Paraquat is banned in the EU.
1023444-012 UNDETERMINED LEGALITY
07/26/2011 PA Possible Likelihood
This incident involves damage to a corn field in Huntington County, PA. One-hundred percent of 130 acres of corn
was damaged after an application of Gramoxone Inteon (a.i. paraquat) was applied at a rate of 1.50pt/A.
1026156-001 UNDETERMINED LEGALITY
01/25/2014 HI Highly Probable Likelihood
This incident involves the death of four dogs and one cat in Kalaheo, HI with paraquat, as determined by Hawaiian
authorities. It is unclear as to whether the restricted-use pesticide was being used on a residential yard or if the
animals came across it elsewhere, according to the Kauai Humane Society field services supervisor.
1027242-001 UNDETERMINED LEGALITY
11/07/2014 Cayman Islands Possible Likelihood
This incident involves the death of a pet owner's dog in the Cayman Islands after ingesting paraquat, as
determined by a local veterinarian.
1029512-00004 UNDETERMINED LEGALITY
4/22/2016 Unknown Location Possible Likelihood
On April 22, 2016 a bee kill involving two hives was reported in North Carolina. Bees began dying on March 30.
There had been no varroa mite threatments made to any of the hives. It was discovered that Gramoxone SL 2.0
(para-quat dichloride), EPA Reg. No. 100-1431 was applied to the field next to the Apiary. No pesticides were
detected in samples. (PDF of incident could not be attached due to inclusion of personal identity information)
Additional Incidents Prior to Previous Reviews but Not Included in Previous Reviews
1014409-001 UNDETERMINED LEGALITY
4/24/1992 WA Possible Likelihood
This incident was reported in the Washington State Dept. of Health Annual Report 1993, Pesticide Incident
Reporting Review Panel, April 1994, prepared by the Washington State Department of Agriculture. It was alleged
that paraquat herbicide drifted onto a radish crop causing damage. Alleged infractor applied a federal restricted
use pesticide without a license or supervision. No action by the State was taken. No analysis.
1013884-038 REGISTERED USE
7/28/1998 WA Probable Likelihood
This is from the 1999 Annual Report from the Washington State Department of Health Pesticide Incident Reporting
and Tracking Review Panel, November 2000, from the 1998 PIRT Data. Over spray of paraquat on peas affected
171
-------
ornamental and vegetable garden plants. State inspector observed paraquat symptoms.
1020627-033 UNDETERMINED LEGALITY
08/01/2001 WA Probable Likelihood
This incident is reported in the Washington State Department of Agriculture annual report 2003 by the Office of
Environmental Health and Safety. The case suspects paraquat poisoning as the cause of death of two dogs and the
cause of the sickening of several other dogs. A vet stated that symptoms were consistent with paraquat poisoning.
Two locations were found where paraquat may have been used.
1020627-036 UNDETERMINED LEGALITY
09/07/2001 WA Probable Likelihood
This incident is reported in the Washington State Department of Agriculture annual report 2003 by the Office of
Environmental Health and Safety. The case involves the alleged drift of paraquat as the cause of damage to alfalfa
fields. The drift caused spotting on the alfalfa.
1020459-025 UNDETERMINED LEGALITY
05/02/2000 WA Probable Likelihood
This incident is reported in the Washington State Department of Agriculture 2002 PIRT Report. The case involves
the alleged drift from the application of paraquat sprayed on sweet corn to winter wheat (seed wheat) in an
adjacent field, causing damage. Approximately 2.5 acres were affected.
1020627-019 UNDETERMINED LEGALITY
06/25/2001 WA Probable Likelihood
This incident is reported in the Washington State Department of Agriculture Annual report 2003 by the Office of
Environmental Health and Safety. The case involves the alleged drift of paraquat from a ground application onto
blueberry plants in an adjacent field. Symptoms of effected plants consistent with drift.
1020998-023 MISUSE
04/19/2002 WA Possible Likelihood
This incident is reported in the Washington State Department of Agriculture annual report 2002 by the Office of
Environmental Health and Safety. The case involves the alleged drift and application of paraquat and
carfentrazone-ethyl on hops field that damaged cherry plants. It is unclear which of the two active ingredients is
responsible for the damage.
1021276-006 UNETERMINED LEGALITY
07/03/2004 WA Probable Likelihood
This incident is reported in the Washington State Department of Health and Pesticide Incident Reporting and
Tracking Review Panel annual report 2005. The case involves the alleged aerial application and drift of paraquat
from an onion field to a corn field in the vicinity, causing damage to the corn.
1021457-015 UNDETERMINED LEGALITY
07/07/2006 WA Possible Likelihood
This incident is reported by the Washington State Department of Health's Division of Environmental Health in
2006. The case involves the drift of paraquat and glyphosate onto an adjacent garden, causing damage to
ornamental plants. The incident was verified by a state inspector, but it is not clear which of the two active
ingredients is responsible for the damage.
172
-------
Appendix F. Crop Attractiveness to Bees
Information on the Attractiveness of Registered Use
Patterns for Paraquat to Bees
Crop Name
Honey Bee
Attractive?1'2
Bumble Bee
Attractive?x-
Solitary Bee
Attractive?2
Acreage in
the U.S.
Notes
Acerola (West Indies Cherry)
Not in Database, info for Mazzard,
Sweet Cherries
Y (pollen2&
nectar1)
Yes1
Yes2
Osmia
868800
Sweet,
36500 Tart
Alfalfa
Medicago sativa
Y (pollen1 &
nectar2)
Yes1
Yes2
Alfalfa
leafcutting bee,
Alkali bee
18 million
Only a small
percentage of
alfalfa is grown for
seed; typically
using managed
alfalfa leafcutting
bees, alkali bees or
honey bees.
Timing of hay or
silage harvest,
relative to bloom,
varies by
agronomic
practice, with
earlier cuts
typically occurring
prior to bloom and
later cuts being
harvested up to
25% bloom.
Almond
Prunus amygdalus; P. communis;
Amygdalus communis
Y (pollen2&
nectar1)
Yes1
Yes1
Osmia
780,000
Apple
Malus pumila; M. sylvestris; M.
communis; Pyrus malus
Y (pollen2&
nectar1)
Yes1
Yes2
Andrena,
Anthidium,
Halictus,
Osmia,
Anthophora,
Habropoda
327,800
Apricot
Prunus armeniaca
Y (pollen2&
nectar2)
Yes2
Yes1
12,150
Artichoke
Cynara scolymus
Y (pollen1 &
nectar1)
Yes1
Yes1
7,000
Asparagus
Asparagus officinalis
Y (pollen1 &
nectar1)
24,500
Only a small % of
asparagus acreage
is grown for seed.
Avocado
Persea americana
Y (pollen1 &
nectar1)
Yes1
59,950
Banana
Y (nectar1)
No
No
1,000
173
-------
Crop Name
Honey Bee
Attractive?1'2
Bumble Bee
Attractive?x-
2
Solitary Bee
Attractive?2
Acreage in
the U.S.
Notes
Musa sapientum; M. cavendishii; M.
nana
Barley
Hordeum spp.
N
No
No
3,000,000
Wind pollinated
Beans, Dried-Type
Represented in database by
Broadbean
Viciafaba
Y (pollen2&
nectar2)
Yes2
Yes1
Anthophora,
Eucra,
Megachile
1,310,000
Cabbages and Other Brassica
Vegetables
This also represents Turnips and
Tyfon
Y (pollen2&
nectar2)
Yes1
Yes1
Cabbage 60,
200
(Annual);
Brussels
Sprouts
7,570
(Census);
Kale 6,250
(Census);
Collards
12,500
(Census)
Only a small % of
acerage is grown
for seed.
Bushberries (e.g., blueberries,
cranberries, gooseberries, currants)
Represented here by Blueberries
and Cranberries
Y (pollen1 &
nectar1)
Yes2
Yes1
Andrena,
Colletes (blue.),
Osmia (blue.),
Anthophora
(blue.),
Agapostemon
(cran.), Melita
(cran.),
Megachile
(cran.)
77,700
blueberries
40,300
cranberries
(also 580 for
currants)
Caneberries (e.g., raspberries, and
blackberries)
Represented here by Raspberries
Y (pollen1 &
nectar1)
Yes2
Yes1
Osmia,
Andema,
Coletes,
Halicutus
17,300
Carrot
Daucus carota
Y (pollen1 &
nectar1)
Yes1
Yes1
Megachile
rotundata
84,710
(71,400
Fresh
Market;
13,310
Processing)
Only a small % of
acreage is grown
for seed.
Cherry
Mazzard, sweet cherry (Prunus
avium; Cerasus avium); hard-
fleshed cherry (var. duracina); heart
cherry (var.juliana)
Y (pollen2&
nectar1)
Yes1
Yes2
Osmia
123,290
(86,790
Sweet;
36,500 Tart)
Citrus
Represented here by Oranges
Y (pollen2&
nectar2)
Yes1
Yes1
Andrena,
613,000
(also 52,100
Variable among
orange cultivars;
174
-------
Crop Name
Honey Bee
Attractive?1'2
Bumble Bee
Attractive?x-
2
Solitary Bee
Attractive?2
Acreage in
the U.S.
Notes
Xylocopa
tangerines
and
mandarins)
honey bees
brought to groves
for orange
blossom honey
Clary
Lamiaceae
Y (pollen1 &
nectar1)
Yes1
Yes1
Not
Available
Note in database
that this is for seed
production, only.
Also that only a
small % of acreage
is grown for seed.
Clover
Trifolium spp
Y (pollen2&
nectar2)
Yes1
Yes2
Megachile,
Osmia,
Andrena,
Anthidium
28,506
White, Red
and Crimson
Only a small % of
acreage is grown
for seed.
Cocoa
Not in Database
Not Available
Not Available
Not Available
Not
Available
Coffee
Represented here by Green
Coffea spp. (arabica, robusta,
liberica)
Y (pollen1)
Yes1
7300
Acreage related to
all coffee, not
specific to green
coffee
Coniferous/Evergreen/Softwood
(Non-Food)
Not in Database
Not Available
Not Available
Not Available
Not
Available
Corn, Field - Also represents
Popcorn and Sweet Corn
Zea mays
Y (pollen1)
Yes1
Yes1
87,668,000
Wind pollinated,
but can be visited
during pollen
shedding
Cotton
Upland cotton (Gossypium hirsutum
)
Pima Cotton (Gossypium
barbardense)
Y (nectar1)
Yes1
Yes1
Halictus,
Anthophora,
Xylocopa,
Megachile,
Nomia,
Ptilothrix
7,664,400
Used by some
beekeepers for
honey production
Cucurbit Vegetables
Represented here by Cucumbers
and Gherkins
Y (pollen1 &
nectar1)
Yes1
Yes1
Melissodes,
Andrena
40,800
Fresh; 82100
for Pickles
Small seed acreage
Deciduous/Broadleaf/Hardwood
(Non-Food)
Not in Database
Not Available
Not Available
Not Available
Not
Available
Eggplant
Solanum melongena
N
Yes2
Yes1
5,004
Only a small % of
acreage is grown
for seed.
Fallow Land
Not in Database
Not Available
Not Available
Not Available
Not
Available
Fig
Ficus carica
N
No
No
8,600
Wasp pollinated
Flowering Plants
Not in Database
Not Available
Not Available
Not Available
Not
Available
175
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Crop Name
Honey Bee
Attractive?1'2
Bumble Bee
Attractive?x-
2
Solitary Bee
Attractive?2
Acreage in
the U.S.
Notes
Fruiting Vegetables
Not in Database
Not Available
Not Available
Not Available
Not
Available
Garlic
Y (pollen1 &
nectar1)
Yes1
Yes1
Not
Available
Rarely grown for
seed.
Ginger
Uncertainty
Uncertainty
Uncertainty
Uncertainty
Note in database
stating that no
data were
identified.
Grapes
Vitis vinifera
Y (pollen1)
No
No
962,100
Wind pollinated
Grass/Turf and
Grasses Grown for Seed
Represented by Grasses Grown for
Forage
Including inter alia: bent, redtop,
fiorin grass (Agrostis spp.);
bluegrass (Poo spp.); Columbus
grass (Sorghum almum); fescue
(Festuca spp.); Napier, elephant
grass (Pennisetum purpureum);
orchard grass (Dactylis glomerata);
Rhodes grass (Chloris gayana);
Phleum, Agropyron, Elymus,
Phalaris, Koeleria,
Stipa, Danthonia, Deschampsia,
Bromus, Trisetum, Calamagrostis,
Carex and Juncus
Y (pollen1)
No
No
35,328,000
Wind pollinated,
source of pollen
only when no
other forage
sources are
available
Guar
(Fabaceae)
Y (pollen1 &
nectar1)
Yes1
Yes1
Not
Available
Extrapolated from
Bean (lupines)
Guava
Not Available
Not Available
Not Available
Not
Available
Hops
Humulus lupulus
Y (pollen1)
No
No
35,224
Kiwi Fruit
Actinidia chinensis
Y (pollen1 &
nectar1)
Yes1
Yes1
4,200
Leafy Vegetables
Not in Database in this grouping
Not Available
Not Available
Not Available
Not
Available
Legume Vegetables
Viciafaba
Also includes Peanuts
Y (pollen2&
nectar2)
Yes2
Yes1
Anthophora,
Eucra,
Megachile
Lentils
Lens esculenta; Ervum lens
Y (pollen1 &
nectar1)
Extra-floral
nectaries
Yes1
Yes1
347,000
Lettuce
Lactuca sativa
Y (pollen1 &
nectar1)
Yes1
Yes1
259,100
Head, leaf,
and romaine
Self-pollinating
Macadamia Nut (Bushnut)
Y (pollen1 &
Not Available
Not Available
Not
176
-------
Crop Name
Honey Bee
Attractive?1'2
Bumble Bee
Attractive?x-
2
Solitary Bee
Attractive?2
Acreage in
the U.S.
Notes
nectar1)
Available
Manioc (Cassava)
Euphorbiaceae
N
No
No
Not
Available
Melons
Represented here by Watermelon
Citrullus vulgaris
Y (pollen1 &
nectar1)
Yes1
Yes1
Agapostemon,
Floridegus,
Halictus,
Hoplitus,
Melissodes
123,300
Mint - not listed in database as
mint but 11 listings were found for
members of the mint family,
Lamiaceae (lemon balm, basil,
catnip, clary, horehound, hyssop,
lavender, marjoram, rosemary,
sage, and savory)
Not Available
- see Notes
Not Available
- see Notes
Not Available -
see Notes
Not
Available
Most of the 11
entries for the
mint family were
at least
opportunistically
attractive to
pollinators.
Okra
Abelmoschus esculentus; Hibiscus
esculentus
Y (pollen1 &
nectar1)
Yes1
Yes1
2,377
Olive
Olea europaea
Y (pollen1)
44,000
Onion
Allium cepa
Y (pollen1 &
nectar1)
No
Yes1
Halictus, Nomia
143,340
Only a small % of
acreage is grown
for seed.
Papaya
Not Available
Not Available
Not Available
Not
Available
Passion Fruit (Granadilla)
Not Available
Not Available
Not Available
Not
Available
Pastureland/Rangeland
Not in Database
Not Available
Not Available
Not Available
Not
Available
Peaches/ Nectarines
Prunus persica, Amygdalus persica,
Persica laevis
Y (pollen1 &
nectar1)
Yes1
Yes1
Osmia
112,900
Peaches
26,400
Nectarines
Pear
Pyrus communis
Y (pollen1 &
nectar1)
Yes1
Yes1
Osmia, Andrena
54,400
Peas (Unspecified)
Garden pea (Pisum sativum); field
pea (P. arvense)
This also represents Peas, Dried-
Type and Peas, Pigeon
Y (pollen1 &
nectar1)
Yes1
Yes1
Eucera,
Xylocopa
797,000
Pepper
In Database as Chilies and Peppers
Y (pollen1)
Yes2
Yes1
71,200 Chile
and Bell
May be grown in
glasshouses, with
bumblebees for
pollination.
Persimmon
Diospyros kaki; D. virginiana
Y (pollen1 &
nectar1)
Yes1
Yes1
4,968
177
-------
Crop Name
Honey Bee
Attractive?1'2
Bumble Bee
Attractive?x-
2
Solitary Bee
Attractive?2
Acreage in
the U.S.
Notes
Pineapple
Not Available
Not Available
Not Available
Not
Available
Pistachio
Pistacia vera
N
No
No
178,000
Wind pollinated.
Plum
Greengage, mirabelle, damson
(Prunus domestica); sloe (P.
spinosa)
This also represents Prunes
Y (pollen1 &
nectar1)
Yes1
Yes1
Osmia,
Anthophora
82,780
Potato, White/Irish (Or Unspecified)
Solanum tuberosum Irish potato
Also used here to represent Yams
and Taro
N
Yes1
Yes1
Andrena
1,052,000
Only small % of
acreage is grown
for breeding
Premises/Areas
Not in Database
Not Available
Not Available
Not Available
Not
Available
Rhubarb
Polygonacaea
See Notes
See Notes
See Notes
Not
Available
Open pollinated,
rarely self-
pollinated. Crop
may be inherently
attractive to bee
pollinators, but
harvested prior to
bloom.
Rice
Oryza spp., mainly Oryza sativa.
N
No
No
2,468,000
Wind pollinated
Root and Tuber Vegetables
Not in Database in this Grouping
Not Available
Not Available
Not Available
Not
Available
Saff lower
Carthamus tinctorius
Y (pollen1 &
nectar1)
Yes1
170,000
Safflower is
basically self-
pollinated, but
bees or other
insects are
generally
necessary for
optimum
fertilization and
maximum yield
Sage
Lamiaceae
Uncertainty
Uncertainty
Uncertainty
Uncertainty
Note in database
stating that no
data were
identified.
Sorghum
Sorghum bicolor, spp. bicolor
Y (pollen1)
Yes1
6,910,000
Grain and
silage
Soybeans
Glycine soja
Y (pollen1 &
nectar1)
Yes1
Yes1
75,869,000
Strawberry
Fragaria spp.
Y (pollen1 &
nectar1)
Yes1
Yes1
Andrena,
58,190
Not essential, but
some growers add
178
-------
Crop Name
Honey Bee
Attractive?1'2
Bumble Bee
Attractive?x-
2
Solitary Bee
Attractive?2
Acreage in
the U.S.
Notes
Halictids, Osmia
supplemental
hives to
compliment wind
pollination
Subtropical/Tropical Fruit
Not in Database in this Grouping
Not Available
Not Available
Not Available
Not
Available
Sugar Beet
Beta vulgaris var. altissima
N
Yes1
1,154,200
Only a small % of
acreage grown for
breeding
Sugarcane
N
No
No
905,600
Wind pollinated
Sunflower
Helianthus annuus
Y (pollen2&
nectar2)
Yes2
Yes2
Halictus,
Dieunomia,
Megachile,
Melissodes,
Svastra,
Xylocopa
1,502,000
(measured
in 2013)
Tobacco
Nicotiana tabacum
Y (pollen1)
Yes1
Yes1
355,700
Typically
deflowered as a
standard
production
practice
Tomato
Lycopersicon esculentum
N
Yes1
Yes1
93,600
Fresh;
277,000
Processing
May be grown in
glasshouses where
bumble bees are
needed for
pollination
Tree Nuts
Not Available
Not Available
Not Available
Not
Available
Trees (Non-Food)
Not in Database
Not Available
Not Available
Not Available
Not
Available
Tuberous and Corm Vegetables
Not in Database in this Grouping
but some specific crops listed here
Not Available
Not Available
Not Available
Not
Available
Vegetables (Unspecified)
Not in Database in this Grouping
Not Available
Not Available
Not Available
Not
Available
Wheat
Triticum spp.: common (T.
aestivum), durum (T. durum), spelt
(T. spelta).
N
No
No
45,157,000
1 attractiveness rating is a single denoting a use pattern is opportunistically attractive to bees.
2 attractiveness rating is a double "++" denoting a use pattern is attractive in all cases
179
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