Environmental Fate and Ecological Risk Assessment for Boscalid

New Use on Rapeseed, Including Canola (Seed Treatment)

Boscalid

CAS 188425-85-6 PC Code 128008

Prepared by

Catherine Aubee, Biologist

David Lieu, Chemist

U.S. Environmental Protection Agency

Office of Pesticide Programs

Environmental Fate and Effects Division (EFED)

Environmental Risk Branch IV

1200 Pennsylvania Ave., NW

Mail Code 7507P

Washington, DC 20460 Reviewed by

Thomas Steeger, Ph.D., Senior Science Advisor

Chuck Peck, Environmental Fate Scientist

Marietta Echeverria, Branch Chief
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Table of Contents

1. Executive Summary ...........................................................................................................................................3

2. Problem Formulation ........................................................................................................................................5

2.1. Nature of Chemical Stressor .....................................................................................................................5

2.2. Stressor Source and Distribution..............................................................................................................5

2.3. Receptors.....................................................................................................................................................6

2.4. Assessment Endpoints................................................................................................................................6

2.5. Conceptual Model ......................................................................................................................................6

2.5.1. Risk Hypothesis .................................................................................................................................6

2.5.2. Conceptual Diagram .........................................................................................................................7

2.6. Analysis Plan ..............................................................................................................................................8

2.6.1. Conclusions from Previous Risk Assessments ................................................................................8

2.6.2. Identification of Data Gaps and Uncertainties ...............................................................................9

2.6.3. Measures of Exposure .......................................................................................................................9

2.6.4. Measures of Effect...........................................................................................................................10

2.6.5. Integration of Exposure and Effects..............................................................................................10

3. Analysis.............................................................................................................................................................11

3.1. Use Characterization ...............................................................................................................................11

3.2. Exposure Characterization......................................................................................................................11

3.2.1. Environmental Fate and Transport...............................................................................................11

3.2.2. Aquatic Exposure ............................................................................................................................13

3.2.3. Terrestrial Exposure .......................................................................................................................16

3.3. Ecological Effects Characterization........................................................................................................17

3.3.1. Ecotoxicity Data...............................................................................................................................17

3.3.2. Incident Reports..............................................................................................................................21

4. Risk Characterization ......................................................................................................................................22

4.1. Risk Estimation ........................................................................................................................................22

4.1.1. Aquatic Organisms..........................................................................................................................22

4.1.2. Terrestrial Organisms.....................................................................................................................23

4.2. Risk Description and Conclusions..........................................................................................................25

4.2.1. Aquatic Organisms..........................................................................................................................25

4.2.2. Terrestrial Organisms.....................................................................................................................27

4.2.3. Conclusions......................................................................................................................................29

5. Federally Threatened and Endangered (Listed) Species of Concern ..........................................................30

5.1. Action Area...............................................................................................................................................30

5.2. Taxonomic Groups Potentially at Risk ..................................................................................................31

5.2.1. Probit Dose-Response Analysis......................................................................................................32

5.2.2. Listed Species Occurrence with Proposed New Use of Boscalid .................................................33

6. References.........................................................................................................................................................35

Appendix A. Chemical names and structures of boscalid and its degradates.....................................................38

Appendix B. PRZM/EXAMS file names and sample input/output data .............................................................39

Appendix C. SCI-GROW sample input/output data .............................................................................................41

Appendix D. Example T-REX (v. 1.4.1) input and output data............................................................................42

Appendix E. Example TerrPlant (v. 1.2.2) input and output data .......................................................................43

Appendix F. Ecotoxicity data gaps and uncertainties ...........................................................................................44

Appendix G. Environmental fate and transport data gaps and uncertainties ....................................................45

Appendix H. LOCATES output of listed species...................................................................................................47
-Page 3 of 52-

1. Executive Summary

Boscalid is a synthetic carboxamide fungicide which is proposed for use as a seed treatment on 

rapeseed (Brassica napus), including canola. The compound has demonstrated at least limited 

systemic activity and residues are persistent and stable to metabolism in plants. Boscalid has a 

moderate potential to reach aquatic environments, including surface and ground water, for 

several months or more following terrestrial application. The available data indicate that 

boscalid is likely to dissipate to some extent through various mechanisms, including runoff, 

erosion, and leaching to ground water. Because boscalid degrades slowly in soil and aquatic 

systems, the compound may persist in soil, in water, and in benthic sediment, once transported or 

partitioned to these environmental compartments.

In aquatic ecosystems, although the octanol-water partition coefficient values for boscalid 

indicate that the compound does not have a strong affinity for sediment, the compound's 

relatively slow degradation rate increases the likelihood that partitioning will occur over time. 

Boscalid adsorbed to soil may also enter the benthic compartment through sedimentation 

processes, although dissipation through other routes (e.g., leaching prior to and following 

sedimentation) will reduce the fraction of adsorbed boscalid available for transport. Overall, 

there is high confidence in the data that show little or no degradation of boscalid residues in soil 

and aquatic systems. However, the presence of unidentified, unextracted residues in the aerobic 

soil metabolism study creates some uncertainty about the extent of persistence of boscalid in soil. 

In the absence of clarifying data, this screening-level assessment makes the conservative 

assumption that unidentified residues are parent boscalid, thereby increasing estimates of 

persistence.

Previous assessments have identified that boscalid is moderately-to-highly toxic to fish and 

aquatic invertebrates, but practically non-toxic to mammals, birds, and terrestrial invertebrates, 

following acute exposure. Chronic effects have been observed in both terrestrial and aquatic 

organisms exposed to boscalid, and toxic effects have been noted in registrant-submitted studies 

with aquatic and terrestrial plants. Ecotoxicity data gaps exist with respect to potential effects on 

sediment-dwelling organisms, acute effects on freshwater invertebrates and passerine birds, and 

potential chronic effects on estuarine/marine organisms. Additional uncertainties surround the 

actual measured concentrations associated with effects in various aquatic studies, although the 

toxicity of boscalid appears to be limited by its solubility.

 

Beekeepers have reported incidents involving honey bee (Apis mellifera) mortality and adverse 

effects on honey bee brood (larval) development, associated with the use of boscalid. Although 

these incidents have not been associated with the Coronet® Fungicide (18.0% boscalid and 9.0% 

pyraclostrobin) end-use product proposed for the new seed treatment use, some of them have 

been associated with another co-formulated product (Pristine® Fungicide, 25.2% boscalid and 

12.8% pyraclostrobin). The reported incidents have been associated with foliar applications of 

boscalid-containing products and not with seed treatment uses. The level of boscalid and/or 

pyraclostrobin that honey bees and other terrestrial invertebrates could be exposed to as a result 

of the proposed seed treatment use is uncertain.
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Based on estimated environmental concentrations (EECs) and the available ecotoxicity data, the 

proposed new use of boscalid as a seed treatment on rapeseed may result in chronic risk to 

terrestrial vertebrates, including birds (reptiles and terrestrial-phase amphibians) and mammals 

that consume treated seed. Acute risk to listed species of birds cannot be precluded, based on 

sublethal effects observed in a subacute dietary test, but frank mortality of birds is not expected. 

Despite the uncertainties regarding the ecotoxicity profile of boscalid, the proposed new use is 

considered unlikely to result in acute or chronic risk to aquatic organisms. The potential for 

adverse effects on aquatic and terrestrial plants is considered low. There is uncertainty regarding 

the potential for adverse effects to larval honey bees from the use of boscalid products coformulated with the fungicide pyraclostrobin; nonetheless, the likelihood of exposure from seed 

treatments is uncertain because, although boscalid demonstrates some systemic activity, the 

extent to which the compound may be translocated to nectar and pollen from a treated seed is 

unknown. Exposure of ground-nesting bees and wasps may be more likely than exposure of 

honey bees, given that the compound is expected to persist in soil and on organic matter.

The potential for direct and indirect effects to listed non-target organisms for which risk is 

assessed as a result of the proposed new use of boscalid is summarized in Table 1.1. This 

screening level assessment does not evaluate risk to terrestrial invertebrates.

Table 1.1. Potential effects to federally listed taxa associated with the proposed new use of boscalid.

Listed Taxon Direct Effects Indirect Effects from Risk to Other Taxa

Yes/No Acute/Chronic Yes/No Through ...

Terrestrial and semiaquatic plants –

monocots and dicots

No NA Yes Acute sublethal1 and chronic effects on birds, 

chronic effects on mammals, when required 

for pollination or seed dispersal.

Birds Yes Acute sublethal1

and Chronic

Yes Chronic effects on mammals that serve as 

prey; acute sublethal1 and chronic effects on 

reptiles and amphibians that serve as prey.

Terrestrial-phase 

amphibians

Yes Acute sublethal1

and Chronic

Yes Chronic effects on mammals which provide 

critical habitat (e.g., burrows) and serve as 

prey.

Reptiles Yes Acute sublethal1

and Chronic

Yes Chronic effects on mammals that serve as 

prey; acute sublethal1 and chronic effects on 

birds, reptiles, and amphibians that serve as 

prey.

Mammals Yes Chronic Yes Acute sublethal1 and chronic effects on birds, 

reptiles, and amphibians that serve as prey; 

chronic effects on mammals that serve as 

prey. 

Aquatic plants No NA No NA

Freshwater fish No NA No NA

Aquatic-phase 

amphibians

No NA Yes Acute sublethal1 and chronic effects on 

terrestrial-phase amphibians.

Freshwater invertebrates No NA No NA

Molluscs No NA No NA

Marine/estuarine fish No NA No NA
-Page 5 of 52-

Marine/estuarine 

invertebrates

No NA No NA

NA Not applicable. 1 Acute risk of sublethal effects in listed species of birds, and therefore in reptiles and terrestrial-phase amphibians, 

could not be precluded based on the submitted ecotoxicity data.

2. Problem Formulation

2.1. Nature of Chemical Stressor

Boscalid is in the carboxamide family of fungicides (FRAC Group 7). The chemical’s mode of 

action is the inhibition of mitochondrial ATP production in fungal cells. Specifically, boscalid 

inhibits the succinate-ubiquinone oxidoreductase system in Complex II of the mitochondrial 

electron transfer chain (proposed label and Wharton 2010). This mode of action is shared with 

the pesticide active ingredients carboxin (CAS Number 5234-68-4) and flutolanil (CAS Number 

66332-96-5).

Coronet® Fungicide, the boscalid end-use product associated with the petition for new use as a 

seed treatment on rapeseed, is co-formulated with the pesticide active ingredient pyraclostrobin 

(18.0% boscalid and 9.0% pyraclostrobin). Pyraclostrobin (CAS Number 175013-18-0) is a 

strobilurin fungicide that inhibits electron transfer in mitochondria by disrupting the ubiquinone 

(Q) cycle at the outer binding site of the cytochrome bc1 complex (i.e., quinone outside inhibitor, 

FRAC Group 11) (proposed label and Wharton 2010).

2.2. Stressor Source and Distribution

Boscalid is a fungicide associated with eight formulated end-use products, labeled for uses on 

food crops (including seed treatments), cotton, ornamentals, and turf. Outside of the registered

uses, boscalid has been used in California, Minnesota, and South Dakota under Section 18 

emergency exemptions. Estimates of the total current usage of boscalid are unavailable.

For the proposed use as a seed treatment on rapeseed, the boscalid end-use product Coronet® will 

be applied to seeds as a water-based slurry or mist. The proposed label does not indicate how 

treated seeds will be planted or applied to the field. Based on publicly available agricultural 

extension documents for canola, used as a surrogate for rapeseed throughout this assessment, it is 

assumed that treated seeds will be broadcast-applied and may be chained in (Boyles et al. 2007). 

The proposed label states 0.12 lb a.i./100 lbs seed as the maximum use rate on rapeseed seed 

treatment. The maximum seeding rate is 10 lb seed per acre (Boyles et al. 2007). Therefore the 

maximum application rate is calculated as 0.012 lbs a.i./A (boscalid). 
-Page 6 of 52-

2.3. Receptors

The receptor is the biological entity that is exposed to the stressor (USEPA 1998). For this 

assessment, the receptor includes terrestrial and aquatic animals inhabiting fields where boscalid

treated seeds are planted and non-target areas to where boscalid is transported (via runoff or 

leaching to groundwater). Consistent with the process described in the Overview Document 

(USEPA 2004), the risk assessment uses a surrogate species approach in its evaluation of 

boscalid. Toxicological data generated from surrogate test species, which are intended to be 

representative of broad taxonomic groups, are used to extrapolate to potential effects on a variety 

of species (receptors) included under these taxonomic groupings. 

2.4. Assessment Endpoints

Assessment endpoints represent the actual environmental value that is to be protected, defined by 

an ecological entity (species, community, or other entity) and its attributes (EPA 1998). For 

boscalid, the ecological entities may include birds, mammals, freshwater fish and invertebrates, 

estuarine/marine fish and invertebrates, terrestrial plants, insects, and aquatic plants and algae. 

The attributes evaluated for each of these entities may include growth, reproduction, and 

survival. 

2.5. Conceptual Model

For a pesticide to pose an ecological risk, it must reach ecological receptors in biologically 

significant concentrations. An exposure pathway is the means by which a pesticide moves in the 

environment from a source to an ecological receptor. For an ecological pathway to be complete, 

it must have a source, a release mechanism, an environmental transport medium, a point of 

exposure for ecological receptors, and a feasible route of exposure.

A conceptual model provides a written description and visual representation of the predicted 

relationships between boscalid (used as a seed treatment), the potential routes of exposure, and 

the predicted effects for each assessment endpoint. A conceptual model consists of two major 

components: the risk hypothesis and the conceptual diagram (EPA 1998).

2.5.1. Risk Hypothesis

For boscalid, the following ecological risk hypothesis is employed for this risk assessment:

Boscalid has slight to moderate mobility in soil and can move to surface water through 

spray drift, runoff, and erosion; it also has limited potential to leach to ground water. 

Based on previous assessments and the compound’s persistence, boscalid is expected to 

pose a chronic risk to small birds, terrestrial-phase amphibians and reptiles and to all size 

classes of mammals. In addition, boscalid may produce adverse effects on survival, 

growth, and/or fecundity of aquatic animals. There is also uncertainty regarding the 

potential risk to benthic invertebrates, given boscalid’s persistence in water and sediment. 

Although not expected to pose a risk to aquatic plants or to monocotyledonous terrestrial 
-Page 7 of 52-

plants, there is uncertainty regarding its potential effects through runoff on dicotyledonous 

terrestrial plants.

2.5.2. Conceptual Diagram

The environmental fate properties of boscalid indicate that runoff represents a potential transport 

mechanism of boscalid to aquatic habitats where non-target organisms may be exposed. It is 

expected that non-target terrestrial organisms can be exposed to boscalid through consumption of 

treated seeds. These transport mechanisms (i.e., sources) are depicted in the conceptual models 

below (Figures 1 and 2) along with the receptors of concern and the potential attribute changes 

in the receptors due to exposures of boscalid. Dotted lines represent transport pathways that are 

assumed to have a low likelihood of occurring and/or of contributing to ecological risk.

Figure 1. Conceptual model for potential boscalid seed treatment effects on aquatic organisms.

Stressor

Source

Receptors

Attribute

Change

Boscalid-treated seeds applied to use site

Fish/aquatic-phase 

amphibians

Eggs 

Larvae 

Juveniles / Adults

Individual organisms

Reduced survival

Reduced growth

Reduced reproduction

Food chain

Reduction in algae

Reduction in prey

Habitat integrity

Reduction in primary productivity

Reduced cover

Community change

Surface water/

Sediment

Runoff

Aquatic Animals

Invertebrates

Vertebrates

Exposure

Media

Uptake/gills 

or integument

Ingestion Ingestion

Wet/dry deposition

Soil Groundwater

Uptake/gills 

or integument

Aquatic Plants

Non-vascular

Vascular

Uptake/cell, 

roots, leaves Riparian plant

terrestrial 

exposure 

pathways see 

Figure 2
-Page 8 of 52-

Figure 2. Conceptual model for potential boscalid seed treatment effects on terrestrial organisms.

2.6. Analysis Plan

The analysis plan is the final step in Problem Formulation. During this step, an assessment 

design is developed, the scope of the assessment is outlined, the methods for conducting the 

assessment are determined, measurements of effects and exposure to evaluate the risk hypothesis 

being delineated, and initial data gaps and assumptions required to address them are identified. 

2.6.1. Conclusions from Previous Risk Assessments

Previously this year, EFED completed a review of the Section 3 request for new uses of boscalid 

on alfalfa (Endura®: 70.0% a.i., and Pristine®: 25.2% a.i. plus 12.8% pyraclostrobin) and citrus 

(Pristine®) (DP Barcode D363523). The proposed maximum single application rates for boscalid 

new uses were 0.48 lbs a.i./A (1.44 lbs a.i./A seasonally) on alfalfa and 0.29 lbs a.i./A (1.17 lbs 

a.i./A seasonally) on citrus. The results of the assessment indicated a potential for direct adverse 

effects to aquatic and terrestrial organisms. Specifically, the application of boscalid according to 

the proposed label specifications was expected to result in acute risk to listed freshwater fish and 

to estuarine/marine molluscs. Chronic risk was identified for freshwater fish and for mammals. 

In addition, reports of honey bee “brood effects” associated with the application of boscalid, 

especially as the Pristine® formulation, suggested a potential for adverse effects on terrestrial 

Stressor

Source

Receptors

Attribute

Change

Boscalid-treated seeds applied to use site

Direct

application

Birds / Terrestrialphase amphibians 

/ reptiles / 

mammals

Seeds

Individual organisms

Reduced survival

Reduced growth

Reduced reproduction

Food chain

Reduction in prey

Habitat integrity

Reduction in primary productivity

Reduced cover

Community change

Terrestrial/riparian plants

grasses/forbs, fruit, terrestrial 

invertebrates 

Runoff

Mammals

Exposure

Media

Soil

Ingestion

Ingestion

Ingestion

Ingestion

Dermal uptake/Ingestion

Root uptake

Wet/dry deposition

Birds / 

Amphibians

Ingestion
-Page 9 of 52-

invertebrates. Although boscalid may reach groundwater, estimated concentrations in 

groundwater for the previously proposed uses indicated that likelihood of adverse effects on 

non-target organisms from groundwater exposure was low. Acute risk to birds and mammals 

and chronic risk to birds did not exceed the Agency’s level of concern (LOC).

Ecotoxicity data gaps previously resulted in the presumption of acute risk to freshwater 

invertebrates and acute (listed species) and chronic risks to estuarine/marine fish and 

invertebrates. Risks to terrestrial dicotyledonous plants (dicots) from spray drift could not be 

precluded based on the available data. However, potential risk to terrestrial monocotyledonous 

plants (monocots) and to dicots exposed to runoff alone did not exceed the Agency’s LOC.

2.6.2. Identification of Data Gaps and Uncertainties

Data gaps and uncertainties in the assessment of the proposed boscalid seed treatment use for 

rapeseed remain the same as those identified in the previous new use assessment for alfalfa and 

citrus (DP Barcode D363523). The absence of and deficiencies in particular ecotoxicity and 

environmental fate studies are discussed in detail in that assessment and in the associated 

transmittal memo of the previous assessment (19 February 2010).

The largest uncertainty in the environmental fate data for boscalid pertains to the unidentified, 

unextracted residues in the aerobic soil metabolism and anaerobic aquatic metabolism studies. In 

this assessment, the unidentified, unextracted residues are conservatively assumed to be the 

parent compound. As described in the previous assessment (DP D363523), revision of the 

aerobic soil metabolism half-life values to reflect the uncertainty regarding unextracted residues 

resulted in higher aquatic PRZM/EXAMS modeling EECs

PRZM/EXAMS may overestimate aquatic EECs for persistent compounds, because peak 

concentrations are not independent. EXAMS uses a standard pond with a static water body of 

fixed volume and no outlet. The model simulates the impact of daily weather on the field over a 

period of thirty years. The pesticide is washed-off into the water-body by the rainfall and runoff 

events. The persistence of boscalid results in accumulation in the water-body, which results in a 

yearly peak concentration that is correlated to each previous year’s peak concentration. In a 

natural environment, over the course of thirty years, some loss of the bioavailable fraction of the 

compound would be expected due to sediment burial and other dissipation processes. 

2.6.3. Measures of Exposure

Screening-level assessments are intended to be protective of wildlife on a national level, as 

opposed to being a regionally- or locally-specific. Therefore, this assessment is not intended to 

represent a spatially- or temporally-specific analysis. Maximum application rates for seed 

treatment on canola, as a surrogate for all proposed rapeseed uses, are used for modeling 

environmental concentrations. Measures of exposure are based on aquatic and terrestrial models 

that calculate estimated environmental concentrations (EECs) using labeled application rates and 

methods. Exposure modeling assumes that the seed treatment use will not result in spray drift. 

Particulate drift, which may occur from abrasion of treated seeds during field application, is not 

assessed in the screening level exposure models. Groundwater is also assessed due to the 
-Page 10 of 52-

moderate leaching potential of boscalid. There are currently no monitoring data for boscalid for 

comparison to model-generated EECs.

Surface water EECs are calculated using the Pesticide Root Zone Model (v3.12.2, May 2005) 

coupled with the Exposure Analysis Model System (EXAMS, v2.98.4.6, April 2005) and using 

the input shell, pe5.pl (August 2006) (USEPA 2006a). Groundwater concentrations are 

estimated using SCIGROW (Screening Concentration in Ground Water), incorporating the same 

method of calculation used in the PRZM and EXAMS modeling. The Terrestrial Residue 

Exposure Model (T-REX, version 1.4.1, 12/11/2008) is used to derive terrestrial EECs on food 

items (USEPA 2008) for terrestrial vertebrates. The TerrPlant model (version 1.2.2, 12/26/2006) 

is used to derive runoff EECs for estimating exposures to terrestrial plants inhabiting dry and 

semi-aquatic areas (USEPA 2006b). These models are parameterized using relevant use and 

environmental fate data according to EFED input parameter guidance.

2.6.4. Measures of Effect

Measures of effect are obtained from a suite of registrant-submitted guideline studies which were 

conducted with a limited number of surrogate species. The test species are not intended to be 

representative of the most sensitive species but rather were selected based on their ability to 

thrive under laboratory conditions. For example, toxicity testing reported in this risk assessment 

utilizes surrogate species to represent all freshwater fish (>2000 species) and birds (>680 

species) identified in the U.S. In addition, the ECOTOXicology database (ECOTOX), was 

searched in November 2010 to provide more ecological effects data for boscalid (CAS 188425-

85-6); however, no additional data were located. 

The acute measures of effect used in this screening level assessment include the median lethal 

dose (LD50), median lethal concentration (LC50), and the median effect concentration (EC50). 

These are measures of acute toxicity which result in 50% of the respective effect in tested 

organisms. The endpoints for chronic measures of effect are the No Observed Adverse Effects 

Concentration (NOAEC) and the No Observed Adverse Effects Level (NOAEL). Toxicity 

studies were submitted for freshwater fish and invertebrates, estuarine/marine fish and 

invertebrates, aquatic and terrestrial plants, birds, mammals and honey bees. The measurement 

endpoints used for risk characterization were derived from studies which underwent review and 

were classified as “acceptable” (conducted under guideline conditions and considered to be 

scientifically sound) or “supplemental” (conditions deviated from guidelines but the results are 

scientifically sound). 

2.6.5. Integration of Exposure and Effects

The exposure and toxicity effects data are integrated to evaluate the risks of adverse ecological 

effects on non-target species. For the screening-level assessment of boscalid, the deterministic, 

risk quotient (RQ) method is used to compare estimated exposure and measured toxicity values. 

The RQ method involves dividing EECs by acute and chronic toxicity values. The resulting RQs 

are then compared to the Agency’s levels of concern (LOCs) (USEPA 2004). These criteria are 

used to indicate if applications of boscalid, as directed on the label, have the potential to cause 

adverse effects to non-target organisms.
-Page 11 of 52-

Although risk is often described in terms of the likelihood and magnitude of adverse effects, the 

risk quotient-based approach does not provide a quantitative estimate of likelihood or magnitude 

of an adverse effect, but rather provides a “yes” or “no” answer depending upon whether or not 

LOCs are exceeded. For example, although a chronic RQ value equal to 4 exceeds the chronic 

LOC and indicates that an EEC is 4 times the highest test concentration where no adverse effects 

were observed in a chronic study; however, this does not imply that adverse effects are 4 times 

more likely to occur.

3. Analysis

3.1. Use Characterization

Boscalid is a fungicide active ingredient (a.i.) included in multiple, formulated end-use products, 

and is registered for use on food crops (including seed treatments), cotton, ornamentals and turf. 

It was first registered by USEPA in 2003. The seed treatment of Coronet® Fungicide is a dualactive ingredient formulation containing 18.0% boscalid and 9.0% pyraclostrobin. Coronet®

seed treatment is registered for use on cole crops (Brassica sp.; not including rapeseed/canola), 

bulb vegetables, cotton, cucurbits, legume vegetables, soybean, and sunflower seeds. 

Application of the fungicide to seeds can be accomplished through water-based slurry, using 

standard slurry or mist-type seed treatment application equipment. The current seasonal rates are

0.015 – 0.12 lbs a.i./100 lbs seed (cwt) based on all previous labels and depending on crop. 

This ecological risk assessment evaluates the use of boscalid as a fungicide (Coronet®) to control

fungal diseases (e.g., Rhizoctonia solani, Phoma lingam, Cladosporium spp., and Penicillium, 

ssp.) of rapeseed, including canola and crambe. Throughout this assessment, canola is used as a 

surrogate for all proposed rapeseed uses. The proposed label for the new use on rapeseed allows 

a maximum application of 0.12 lbs a.i. per 100 lbs of seed (cwt). Canola seed is planted at 4 to 

10 lbs seed per acre (Boyles et al. 2007), which corresponds to a maximum application rate of 

0.012 lbs a.i./A (0.013 kg ai/ha)1

. This maximum application rate is used as the basis of 

screening-level calculations for aquatic and terrestrial exposure.

3.2. Exposure Characterization

3.2.1. Environmental Fate and Transport

The environmental fate and transport properties of boscalid and a description of the total toxic 

residue (TTR) modeling approach employed in this assessment are discussed in detail in the 

 1 At maximum seeding rate of 10 lbs seed/Acre and the maximum seed treatment rate of 0.012 lbs ai/A: 10 lbs/A x 0.12 lbs 

a.i./100 lbs seed = 0.012 lbs ai/A (equivalent to 0.013 kg ai/ha); at the maximum seeding rate of 10 lbs seed/A and the minimum 

seed treatment rate of 0.015 lbs ai/100 lbs seed: 10 lbs/A x 0.015 lbs ai/100 lbs seed=0.0015 lbs ai/A (0.0017 kg ai/ha); at the 

low seeding rate of 4 lbs seed/A and the minimum seed treatment rate of 0.015 lbs ai/100 lbs seed: 4 lbs/A x 0.015 lbs ai/100 lbs 

seed=0.0006 lbs ai/A (0.0007 kg ai/ha) . 2 EFED 2009 updated input parameter guidance is located at: 

http://www.epa.gov/oppefed1/models/water/input_parameter_guidance.htm
-Page 12 of 52-

recent assessment for proposed new uses on alfalfa and citrus (DP Barcode D363523). Table 

3.1 summarizes the physicochemical and environmental fate properties of boscalid, which are 

utilized according to the Input Parameter Guidance2 in aquatic and terrestrial exposure modeling. 

Overall, boscalid is slowly biodegradable with slight to moderate mobility in most soils (Koc

ranges from 507 to 1,110 mL/g). The primary degradation pathway is aerobic soil metabolism. 

Unextracted, unidentified residues in the aerobic soil metabolism study resulted in uncertainty 

and suggest that the half-lives may be as long as 848 to 2,553 days, when it is presumed that 

these residues are parent compound. A half-life of 182 to 578 days is calculated with only the 

identified parent compound. Given its persistence and moderate mobility, transport of boscalid to 

surface water via runoff of dissolved or sediment-bound residues (erosion) is probable. A higher 

potential for leaching into ground water exists for the compound in soils which are lower in 

organic matter; however, the Kd values (3.3 to 28 mL/g) suggest that this may occur only 

infrequently. The solubility of boscalid has been listed at 6 mg/L in previous assessments (DP 

Barcode D342975, D337648, and D336599); however, a secondary product chemistry review 

analysis of the available data indicates the correct solubility value is 4.64 mg/L at 20oC (DP 

Barcode D285692). The vapor pressure value, which has been listed as 7.5 x 10-8 torr at 25oC in 

previous assessments (DP Barcode D342975, D337648, and D336599). According to a 

secondary product chemistry review (DP Barcode D285692), the correct value should have been 

reported as 1.5 x 10-8 torr at 25oC. This assessment uses these updated values.

The degradates of boscalid include 2-chloronicotinic acid (M510F47), 2-hydroxy-N-(4'-

chlorobiphenyl-2-yl)-nicotinamide (M510F49), p-chloro-benzoic acid (M510F64), an unknown 

(M510F50) and carbon dioxide. M510F47 and M510F50 are classified as minor degradates. 

M510F49 is classified as a major degradate but was only observed at recoveries greater than 

10% of the applied parent in one soil; it was a minor degradate in the rest (MRID 45405208 and 

45643802). An additional study provided for the degradate M510F49 reported an aerobic soil 

metabolism half-life of 1.7 days. Therefore there are no environmental degradates of concern in 

this ecological risk assessment. (MARC Memo 2003). More information about boscalid 

degradates is provided in Appendix A.

Table 3.1 Chemical properties and environmental fate parameters of boscalid.

Parameter Value Reference

Nomenclature

Chemical name Boscalid -

IUPAC 2-chloro-N-(4'-chlorobiphenyl-2-

yl)nicotinamide

-

CAS RN 188425-85-6 -

Selected Physical/Chemical Parameters

Molecular mass 343.2 g/mol -

Vapor pressure (25°C) 1.5x10-8 Torr DP 285692

Water solubility (20°C) 4.64 mg/L DP 285692

Octanol-water partition coefficient (log KOW) 2.96 DP 285692

Persistence

Hydrolysis half-life pH 5

(25°C) pH 7

 pH 9

Stable MRID 45405205

Aqueous photolysis half-life Stable MRID 45405206

Soil photolysis half-life Stable MRID 45405207

Aerobic soil metabolism half-life 848 days (clay loam)1 MRID 45643802
-Page 13 of 52-

1,000 days (silt loam)1

1,609 days (clay loam)1

2,553 days(loam)1

Aerobic aquatic metabolism half-life Stable MRID 45405214

Anaerobic aquatic metabolism half-life Stable MRID 45405213

Mobility

Organic carbon partitioning coefficient (KOC) 507 – 1,110 mL/gOC

772 mL/gOC (mean)

MRID 45405216

MRID 45405217 1 Aerobic soil metabolism half-life calculated with the unidentified unextracted residues.

Bioconcentration factors (BCF) from two studies with rainbow trout (Oncorhynchus mykiss) 

exposed to boscalid in water were 36-44X, 84-105X, and 57-70X for the edible, non-edible, and 

whole fish tissues, respectively. Boscalid depurates rapidly from the tissues when exposure 

ceases. Boscalid is metabolized in fish tissues to form the metabolite M510F01, the oxygenated 

form of the compound, and is conjugated with cysteine to form M510F05.

3.2.2. Aquatic Exposure

Because boscalid may be transported from crop sites to adjacent surface water and persists once 

partitioned to sediment (mean Koc = 772 mL/g, stable to anaerobic aquatic metabolism), 

estimated environmental concentrations (EECs) in both surface water and pore water were 

generated based on maximum labeled use rates (Table 3.2 and Table 3.3) using PRZM and 

EXAMS in tandem with the input shell pe5v0 (Nov 15, 2006). 

Table 3.2 Input parameters used as surface and pore water exposure modeling (PRZM/EXAMS).

Input Parameter Value Source Comment

Vapor pressure (25oC) 1.5x10-8

Torr

DP Barcode D285692 -

Henry's law constant - Not determined Did not use as an input parameter

Water solubility 4.64 mg/L DP Barcode D285692 pH 5-7, 20oC

Organic carbon partitioning 

coefficient (Koc)

772 mL/goc MRID 45405216

MRID 45405217

Calculated mean Koc

Aerobic soil metabolism (t1/2) 2,0731 days MRID 45405208

MRID 45405209

MRID 45643802

90th percentile of the upper 

confidence bound on the mean 

half-life of four soils.

Aerobic aquatic metabolism (t1/2) 4,146 days Input Parameter 

Guidance2

Double the aerobic soil 

metabolism half-life input 

parameter

Anaerobic aquatic metabolism 

(t1/2)

0 days MRID 45405213 No significant degradation

Hydrolysis (t1/2) 0 days MRID 45405205 No significant degradation

Photolysis in water (t1/2) 0 days MRID 45405206 No significant degradation

Foliar degradation rate 0 d-1 Input Parameter 

Guidance2

Default
-Page 14 of 52-

1 Aerobic soil metabolism half-life value was recalculated in DP Barcode D367184 to include unidentified, unextractable 

residues

2 EFED 2009 updated input parameter guidance is located at 

http://www.epa.gov/oppefed1/models/water/input_parameter_guidance.htm

Modeling inputs were selected according to EFED’s Input Parameter Guidance and the IPM 

Crop Profile for Canola in Minnesota. Rapeseed is planted from late April through early May; 

aquatic exposure modeling was based on an application date of April 30th. Optimal seeding 

depth is between 0.5 and 1 inch at a rate of 4 to 10 lbs of seeds per acre (based on canola, Boyles 

et al. 2007). The seeds are typically broadcast and then chained in. NDcanolaSTD was selected 

as the most representative scenario for the proposed seed treatment use on rapeseed. A value of 

1 was assigned to represent the disposition of foliar residues because the seed treatment is 

surface-applied. Similarly, the Chemical Application Method (CAM) value for seed applications 

is 1 because it is surface applied and chained in. Seed application was assumed to have 100% 

application efficiency and 0% spray drift. The Koc value was used instead of the Kd value for 

both models because boscalid partitioning is correlated with organic carbon content. The 

coefficient of variation for Koc (0.30) is less than that for Kd (0.90).

Table 3.3 Aquatic exposure modeling inputs for boscalid ecological risk assessment (PRZM/EXAMS).

Input Parameter Value Source Comment

Application rate 0.013 kg a.i./ha3

0.012 lbs a.i./A

Proposed label,

Reg. 7969-274

Label directions

Application per season 1 Proposed label,

Reg. 7969-274

Label directions

Date of first 

application

MN canola: April 30th USDA agricultural crop

profiles information1

Application dates are specific 

to factors from the listed 

source

Reapplication intervals N/A Proposed label,

Reg. 7969-274

Label directions

Chemical Application 

Method (CAM)

1 - Surface applied 

(broadcast, not 

incorporated)

- See text

Disposition of foliar 

residues

1 USDA agricultural crop

profiles information1

Seed treatment is surface 

applied

Spray Drift Fraction 0.0 – Seed treatment 

(Chained in)

- See text

Application Efficiency 1.0 - Seed treatment 

(Chained in)

- See text

Scenario NDcanolaSTD Scenario parameters See explanation below

1

USDA Crop Profiles information is located at: http://www.ipmcenters.org/cropprofiles/CP_form.cfm. 2

EFED 2009 updated input parameter guidance is located at: http://www.epa.gov/oppefed1/models/water/input_parameter_guidance.htm 3

Equivalent application rate based on maximum seeding rate of 10 lbs seed/Acre and the maximum seed treatment rate of 0.12 lbs ai/A: 10 lbs/A 

x 0.12 lbs a.i./100 lbs seed = 0.012 lbs ai/A (equivalent to 0.013 kg ai/ha)

Boscalid may dissipate through multiple pathways and is expected to have a moderate potential 

to leach into ground water. The regression-based Screening Concentration in Ground Water 

(SCI-GROW v2.3, Jul. 29, 2003) model, was used to calculate boscalid concentrations in a 

shallow, unconfined aquifer under sandy soils, i.e., the ground water scenario expected to be 
-Page 15 of 52-

most vulnerable to pesticide contamination. The calculated concentrations from SCI-GROW are 

driven by the Relative Index of Leaching Potential (RILP), which is a function of aerobic soil 

metabolism and the soil-water partition coefficient (Kd), and the application rate and methods for 

the proposed new use of boscalid as a seed treatment on rapeseed. SCI-GROW input parameter 

values are summarized in Table 3.4.

Table 3.4. Input parameters for estimated concentrations of boscalid in ground water (SCI-GROW).

Input Parameter Value Source Comment

Application rate 0.012 lbs a.i./A Proposed label,

Reg. 7969-274

Label directions

Application per season 1 Proposed label,

Reg. 7969-274

Label directions

Organic carbon 

normalized partition 

coefficient (Koc, 

L/kgoc)

716 MRID 45405216

Input Parameter Guidance2

Median Koc for six soils

Aerobic soil 

metabolism half-life 

(t1/2, days)

1,305 MRID 45643802

Input Parameter Guidance2

Median of four values in the 

acceptable study

1 Value represents total toxic residues which include parent and unextracted residues (DP367184, September 2009).

2 EFED 2009 updated input parameter guidance is located at: http://www.epa.gov/oppefed1/models/water/input_parameter_guidance.htm

Aquatic exposure endpoints in this assessment are determined using yearly peak concentrations. 

However, in the case of persistent compounds such as boscalid, the yearly peaks are not 

independent; they are correlated to the previous year’s peak concentration. This is because the 

standard pond modeled with EXAMS is a static water body of fixed volume with no outlet.

Therefore, the estimated concentration of boscalid in water is expected to increase over time 

because of the slow degradation rate, and a 1-in-10 year peak EEC does not necessarily or 

exclusively reflect meteorological conditions at that time (i.e., a peak water column EEC is not 

necessarily associated with a “hundred year” storm). PRZM/EXAMS may overestimate aquatic 

EECs, as, over the course of thirty years, some loss of boscalid would be expected due to 

sediment burial and other dissipation processes. There is also uncertainty in the degradation rate, 

which is effected by the assumption that the unidentified, unextracted residues are parent 

compound and that they are available to biological receptors.

The EECs in Table 3.5 reflect maximum 1-in-10 year surface water and pore water 

concentrations, based on dissolved and unidentified/unextracted residues presumed to be parent 

boscalid, from maximum proposed application rates for treated rapeseed (using the canola 

scenario as a surrogate for all proposed rapeseed uses). Pore water EECs represent the estimated 

concentration of boscalid that are present in the pore water of the benthic sediment phase of a 

static water body (e.g., pond), where benthic organisms are expected to inhabit. Because the 

standard pond has no outlet, there is an accumulation of boscalid in the pond throughout the 30 

year simulation period.
-Page 16 of 52-

Table 3.5 Tier II surface water and pore water estimated environmental concentrations (EECs) of boscalid 

from seed treatment on rapeseed

Proposed

Use

App Rate

(lbs a.i./A)

(Formulation)

Scenario 

(Weather)

App

Method

Compartment EECs (μg/L)

Peak 1-in-10-yr

21-d avg

1-in-10-yr

60-d avg

Canola 0.012

(Coronet®)

NDcanolaSTD

(w24013)

Seed 

treatment

Surface water 0.72 0.72 0.72

Pore water 0.71 0.71 0.71

Abbreviations: App - Application. Avg - Average. d -Day. yr - Year.

The estimated ground water concentrations reported in Table 3.6 represent concentrations that 

might be expected in shallow, unconfined aquifers under sandy soils, which are expected to be 

most vulnerable to pesticide contamination. 

Table 3.6 Summary of Tier I estimated concentrations of boscalid residues in ground water.

Use Use/Application Rate (lbs a.i./A) EECs (μg/L)

Acute and Chronic

Canola Seed treatment/0.012 x 1 applications; annual total of 0.012 0.01

3.2.3. Terrestrial Exposure

T-REX is used to calculate dose-based EECs of boscalid for birds and mammals that consume 

treated seeds. Seeding rates for canola (Boyles et al. 2007), as a surrogate for all proposed 

rapeseed uses, and the maximum application rate according to the proposed label are used to 

calculate dose-based EECs (Nagy dose) and the mass of boscalid per unit area (mg ai/ft2) 

available for consumption by birds and mammals (Table 3.7). 

Table 3.7. Avian and mammalian dose-based EECs calculated for the proposed new use of boscalid as a seed 

treatment on rapeseed, based on seeding rate for canola (T-REX).

Use App Rate

(lbs a.i./100 

lbs seed)

Seeding 

Rate1

(lbs

seed/A)

App Rate 

(lbs a.i./A)

Seed

App Rate 

(mg a.i./

kg seed)

Nagy Dose

(mg a.i./kg-bw/day)

Spatial

(available 

a.i. per unit 

area) 

(mg a.i. /ft2)

Birds Mammals

Canola 0.12 10 0.012

(0.013 kg ai/A) 1200 304 254 0.13

Abbreviations: App Application. cwt Hundred weight (100 lbs seed). 1

Reference: Boyles et al. (2007).

TerrPlant is used to calculate EECs for non-target plants that inhabit dry and semi-aquatic areas. 

In this assessment, exposure to non-target plants is calculated based on the potential runoff of 

boscalid following the broadcast application of treated seeds on the field (Table 3.8). Potential 

exposure resulting from spray drift is not calculated because any spray drift of boscalid 

associated with the seed treatment use is expected to be negligible. TerrPlant does not account 

for particulate drift.
-Page 17 of 52-

Table 3.8. Terrestrial plant EECs for nontarget plants exposed to boscalid through runoff, based on the 

proposed use of boscalid as a seed treatment on rapeseed (TerrPlant). Canola is used as a surrogate for all 

proposed rapeseed uses.

Use Single Max. Application Rate

(lbs a.i./A)

Runoff EECs (lbs a.i./A)

Dry Areas Semi-Aquatic Areas

Canola 0.012 <0.001 0.001

3.3. Ecological Effects Characterization

3.3.1. Ecotoxicity Data

A detailed description of the available ecotoxicity data for boscalid is provided in the most recent 

risk assessment for proposed new uses on alfalfa and citrus (DP Barcode D363523). No new 

ecotoxicity data have been submitted. Toxicity endpoints used in risk estimation and 

characterization for the proposed use of boscalid as a seed treatment on canola are shown in 

Table 3.9 and Table 3.10. These endpoints represent the most sensitive endpoints available 

from suitable, guideline toxicity studies. A search of the ECOTOX database in November 2010 

returned no other acceptable ecotoxicity studies for boscalid.

Based on the available data, boscalid is moderately toxic to freshwater fish and at least 

moderately toxic to freshwater invertebrates on an acute exposure basis, at concentrations 

approaching its water solubility limit; however, the submitted acute test with freshwater 

invertebrates (MRID 45405001) is not used quantitatively for risk estimation because it may 

have overestimated the actual exposure concentrations of the test organisms and thus 

underestimated the toxicity endpoint (see DP Barcode D363523 for discussion). Non-definitive 

toxicity endpoints indicate that boscalid is moderately toxic to benthic invertebrates, 

estuarine/marine fish and to non-molluscan estuarine/marine invertebrates on an acute exposure 

basis. However, it is highly toxic to estuarine/marine molluscs based on reductions in shell 

growth.

Chronic toxicity has been demonstrated for freshwater fish based on reduced survival and for 

freshwater invertebrates (i.e., waterflea) based on reduced survival and growth (decreased length 

and dry weight) and impaired reproduction (reduced number of young). Acceptable chronic 

toxicity data for other aquatic animals, including benthic freshwater invertebrates and 

estuarine/marine fish and invertebrates, are unavailable. Specifically, the chronic study for 

benthic freshwater invertebrates (i.e., midge) was inadequate because sediment was not spiked. 

However, the available supplemental data indicate that boscalid can reduce emergence and 

development in the midge and reduce growth (decreased dry weight) in the freshwater amphipod. 

No chronic studies were submitted for estuarine/marine fish or invertebrates.

Exposure of aquatic vascular plants (Lemna gibba; duckweed) to boscalid at 3.9 mg/L did not 

result in sufficient inhibition of frond growth or biomass to estimate an IC50; exposure of 

nonvascular plants, i.e., green algae (Pseudokirchneriella subcapitata) to boscalid resulted in a 

50% inhibition of cell growth at 1.34 mg/L. 
-Page 18 of 52-

Table 3.9 Toxicity endpoints used in risk estimation and characterization for aquatic organisms exposed to 

boscalid residues.

Aquatic Animals

Acute Toxicity

Study Type Species Endpoints1

(mg a.i./L)

Toxicity Classification 

(MRID)

Acute toxicity to freshwater fish Rainbow trout

(Oncorhynchus mykiss) LC50 = 2.7 Moderately toxic(45404927)

Subacute sediment toxicity to 

freshwater invertebrates

Freshwater amphipod

(Hyalella azteca)

EC50 > 1.066 

NOAEC = 0.298 

(pore water)

Moderately toxic

(45405009)

Acute toxicity to 

estuarine/marine fish

Sheepshead minnow

(Cyprinidon variegatus) LC50 > 3.86 Moderately toxic(45405004)

Acute toxicity to 

estuarine/marine invertebrates

Mysid shrimp

(Americamysis bahia

formerly Mysidopsis 

bahia)

LC50 > 3.81 Moderately toxic

(45405002)

Toxicity to estuarine/marine 

molluscs – shell deposition

Eastern oyster

(Crassostrea virginica)

EC50 = 1.02

(2.14, 0.89 - 3.39)

Highly toxic

(45405003)

Chronic Toxicity

Study Type Species NOAEC & LOAEC

(mg a.i./L)

Effects

(MRID)

Early life stage toxicity to 

freshwater fish

Rainbow trout

(Oncorhynchus mykiss) 0.116 & 0.241 Mortality(45405006)

Chronic toxicity to freshwater 

invertebrates

Waterflea

(Daphnia magna) 0.79 & 1.54 Reduced number of young 

(46351406)

Chronic toxicity to sedimentdwelling invertebrates (spiked 

water)

Freshwater midge

(Chironomus riparius)

2.0 & 4.0 nominal 

(overlying water)

Reduced emergence

(45405008)

Aquatic Plants

Study Type Species Endpoints

(mg a.i./L)

Effects (MRID)

Toxicity to vascular aquatic 

plants

Duckweed

(Lemna gibba)

IC50 > 3.9

NOAEC = 0.99

Frond number, necrosis 

(45405013)

Toxicity to nonvascular aquatic 

plants

Freshwater alga

(Pseudokirchneriella 

subcapitata)

IC50 = 1.34

NOAEC = 0.49

Growth rate, biomass

(45405017)

1

 Dose-response slope values for the estuarine/marine mollusc are indicated in parentheses (value, 95% confidence 

interval). For other studies, where slope data are not available, the default value of 4.5 (with 95% confidence 

intervals of 2.0 and 9.0) is used to derive the probability of an individual effect (Urban and Cook 1986).

Based on the available data, boscalid is practically non-toxic to terrestrial invertebrates (e.g., 

adult honey bees, Apis mellifera) on both an acute contact and acute oral exposure basis, to birds 

on both an acute oral and subacute dietary exposure basis, and to mammals on an acute oral 

exposure basis. However, adverse effects on honey bee larval development have been reported 

in incident data following application of boscalid, specifically as the Pristine® formulation, to 

almonds and other unspecified crops.
-Page 19 of 52-

In birds and mammals, chronic exposure to boscalid was associated with reproductive and 

growth effects, including reduced number of eggs and embryo mortality in bobwhite quail 

(Colinus virginianus) and reduced F2 body weight in rats (Rattus norvegicus). Based on the 

results of the Tier II terrestrial plant studies, cabbage (Brassica oleracea) appears to be 

particularly sensitive to boscalid exposure, while other dicot species and all tested monocots are 

relatively insensitive to boscalid exposure.

Table 3.10 Toxicity endpoints used in risk estimation and characterization for terrestrial organisms exposed 

to boscalid.

Terrestrial Animals

Acute Toxicity

Study Type Species Endpoints1

(LD50 mg a.i./kg bw)

(LC50 mg a.i./kg diet)

Toxicity Classification 

(MRID)

Acute oral toxicity to upland 

game birds

Bobwhite quail

(Colinus virginianus) LD50 > 2000 Practically nontoxic(45404922)

Subacute dietary toxicity to 

upland game birds and 

waterfowl

Bobwhite quail

(Colinus virginianus)

Mallard duck

(Anas platyrhynchos)

LC50 > 5000

Practically nontoxic

(45404923)

(45404924)

Acute oral toxicity to 

mammals2

Norway rat

(Rattus norvegicus) LD50 > 5000 Practically nontoxic(45404814)

Acute contact and oral 

toxicity to honey bees

Honey bee

(Apis mellifera)

LD50 > 166 μg/bee

(oral)

LD50 > 200 μg/bee

(contact)

Practically non-toxic

(45405019)

Toxicity to soil dwelling 

invertebrates (14-day)3

Earthworm

(Eisenia foetida)

LD50 > 1000 mg a.i./kg 

dry weight soil 

(nominal)

NA

(45405020)

Chronic Toxicity

Study Type Species NOAEC

(mg a.i./kg diet)

NOAEL

(mg a.i./kg bw)

Effects

(MRID)

Avian reproduction with 

upland game birds

Bobwhite quail

(Colinus virginianus)

NOAEC = 300

NOAEL = 25

Number of eggs laid, 

fertility rate, embryo

mortality, and number of 

14-day survivors

(45404925)

Chronic toxicity to mammals2

– two-generation 

reproduction

Norway rat

(Rattus norvegicus)

NOAEC = 100

NOAEL = 11.2

Decreased F2 body weight

(45404906)

Terrestrial Plants

Study Type Most Sensitive Species IC25 & NOAEC

(lbs a.i./A)

Effects (MRID)

Tier II seedling emergence 

(Emerald, 69.9% a.i.)

Monocot: Corn

Dicot: Cabbage

> 0.576 & 0.275

0.44 & 0.275

Seedling emergence

Dry weight

(47627401)

Tier II vegetative vigor 

(Emerald, 69.9% a.i.)

Monocot: Corn

Dicot: Cabbage

> 0.626 & 0.035

< 0.035 & < 0.035

Shoot length

Dry weight

(47627402) 1

 Slope data were not available from the acute terrestrial studies. The default value of 4.5 (with 95% confidence 

intervals of 2.0 and 9.0) is used to derive the probability of an individual effect (Urban and Cook 1986).

2 Mammalian toxicity data provided and reviewed by OPP Health Effects Division (USEPA).
-Page 20 of 52-

3

 The submitted earthworm study was labeled as an acute test, although the duration (14 days) was considerably 

longer than most acute toxicity tests. The guideline-recommended duration for a chronic test with earthworms is 

28 days.
-Page 21 of 52-

3.3.2. Incident Reports

The Ecological Incident Information System (EIIS), which is maintained by the Agency’s Office 

of Pesticide Programs, was searched to determine if ecological incidents have been reported for

boscalid. Because of limitations in the incident reporting system, the lack of additional incident 

reports cannot be construed as the absence of incidents from the registered use of boscalid. At 

the time of the search, EIIS contained information on incidents reported through December 2008.

Based on a search of EIIS conducted in October 2010, one ecological incident with honey bees 

was reported for boscalid (USEPA 2010). Communications from the registrant (BASF 2008) 

indicate further concern on the part of beekeepers for potential effects on honey bee brood 

development. Although no acute toxicity to adult honey bees has been demonstrated in 

laboratory studies with boscalid, individual beekeepers have reported honey bee “brood effects” 

following the application of boscalid, specifically as the Pristine® formulated product (25.2% 

boscalid and 12.8% pyraclostrobin), to nearby crops (BASF 2008). For example, a California 

beekeeper reported that “brood effects” were observed within ten days of the application of 

Pristine® (application rate and target crop unspecified; BASF 2008; USEPA 2010). Other 

beekeepers reported concerns to the registrant regarding “improper [brood] development” 17 

days after application of Pristine® to almonds (BASF 2008). Additionally, “adverse effects” on 

larval development were noted after queen bees were fed almond pollen from Pristine® treated 

crops, but the nature and magnitude of these effects were not reported (BASF 2008). The 

mechanism of these alleged effects is likewise unknown. Some data have been presented to 

suggest that carboxamide pesticides, including boscalid, may interfere with hormonallyregulated development in juvenile honey bees (eg. Mussen 2009, Frazier et al. 2008, Ladurner et 

al. 2005, Mussen et al. 2004, Atkins and Kellum 1986). However, this hypothesis has not been 

rigorously tested. 

The National Pesticide Information Center (NPIC) reported one incident associated with a 

putative misuse of boscalid in Utah (Stone 2010). Application rates were unknown, but the 

report indicated that products were likely tank mixed. The incident report described dead bees, 

lost hives, and hives in poor health with no honey crop despite fall feedings; observations of 

adverse effects were made from June through December 2009. Laboratory tests confirmed the 

presence of boscalid residues (149 ng a.i./g wax) and residues of other pesticide active 

ingredients, including pyraclostrobin, chlorothalonil, 2,4-dimethylphenyl formamide, 

chlorpyrifos, cyprodinil, diflubenzron, and tebuconazole. Aerial spray applications of Bravo®

(chlorothalonil) flowable concentrate and Elite® (tebuconazole) dry flowable fungicide were 

identified in the report as well. The report has not been verified, although laboratory results of 

residue analysis have been submitted.

The Avian Incident Monitoring System (AIMS), a database maintained by the American Bird 

Conservancy (2010), was searched in October 2010 and returned no incidents related to the use 

of boscalid.
-Page 22 of 52-

4. Risk Characterization

Toxicity data and exposure estimates for boscalid are used to evaluate the potential for adverse 

ecological effects on non-target species. This screening-level assessment employs a deterministic 

risk estimation method, based on risk quotient (RQ) values, to provide a metric of potential risks

(Section 4.1). The potential for risk is characterized further in the Risk Description (Section 4.2) 

based on the risk estimation results and other relevant information about toxicity, incidents, 

ecosystems potentially at risk, and the environmental fate and transport characteristics of 

boscalid. In cases where an RQ value exceeds the listed species LOC, the potential for risk to 

listed species is characterized in greater detail in Section 5. The LOCATES database is queried 

to identify listed species that may co-occur within potential use areas for the proposed action, 

i.e., areas where rapeseed (including canola and crambe) is grown and where the proposed new 

use of boscalid as a seed treatment may occur. 

4.1. Risk Estimation

Unitless RQ values are compared to the Agency’s LOCs to identify taxonomic groups potentially 

at risk of acute or chronic effects associated with the proposed new use of boscalid as a seed 

treatment on rapeseed.

4.1.1. Aquatic Organisms

RQ values are calculated for acute and chronic risk to fish and aquatic invertebrates, including 

molluscs, where the submitted ecotoxicity data are sufficient to use in risk estimation. As shown 

in Table 4.1, none of the RQ values calculated either approach or exceed the Agency’s levels of 

concern (LOCs) for acute or chronic risk to listed or nonlisted species of aquatic organisms, nor 

do they exceed LOCs for risk to nonvascular aquatic plants (e.g., algae) or to listed vascular 

aquatic plants.

The submitted data are insufficient to calculate RQ values for (1) acute risk to freshwater 

invertebrates, (2) acute and chronic risk to benthic invertebrates, (3) acute and chronic risk to 

estuarine/marine fish and non-molluscan invertebrates, and (4) risk to nonlisted species of 

vascular aquatic plants. These data gaps and uncertainties are described in more detail in the 

recent assessment of boscalid proposed uses on alfalfa and citrus (DP Barcode D363523). 

Further characterization of the potential for adverse effects to aquatic organisms, based on the 

available data, is provided as part of the Risk Description in Section 4.2.1. 
-Page 23 of 52-

Table 4.1. Acute and chronic RQ values for aquatic organisms exposed to boscalid in surface water following 

seed treatment use on rapeseed, based on seeding rate for canola.

Use

App

Rate

lbs a.i./A

(#app)

App 

Method

EECs

(μg/L) Toxicity Endpoints RQ Values

Peak 21-d 60-d Aquatic Animals Acute Chronic

Canola 0.012

(1)

Seed 

Treatment 0.72 0.72 0.72

Freshwater Fish

LC50=2.7 mg/L

NOAEC=0.116 mg/L

<0.001 0.006

Freshwater Invertebrate 

EC50=NA

NOAEC=0.79 mg/L

NA1 0.001

Estuarine/Marine Mollusc 

EC50=1.02 mg/L

NOAEC= NA

0.001 NA2

Peak Aquatic Plants Listed Nonlisted

Canola 0.012

(1)

Seed 

Treatment 0.72

Vascular Plants

IC50 > 3.9 mg/L

NOAEC = 0.99 mg/L

0.001 NA3

Nonvascular Plants

IC50 = 1.34 mg/L

NOAEC = 0.49 mg/L

0.002 0.001

1

 An acute freshwater invertebrate study was submitted (MRID 45405001); however, the results are not used in 

risk estimation because they may underestimate toxicity (see DP Barcode 363523 for discussion). Potential acute 

risks to freshwater invertebrates are discussed as part of the Risk Description (Section 4.2). 2

 Chronic toxicity data for molluscs have not been submitted. 3

 An RQ value for risk to nonlisted species of vascular aquatic plants is not calculated because the most sensitive 

toxicity endpoint (IC50) is a non-definitive value. NA Not available.

4.1.2. Terrestrial Organisms

RQ values are not calculated for acute risk to birds or mammals in this assessment because the 

acute toxicity endpoints for boscalid are nondefinitive, i.e., the LD50 values are greater than the 

limit dose. RQ values for chronic risk to birds and mammals, based on the proposed use of 

boscalid as a seed treatment on rapeseed (maximum application rate = 0.12 lbs a.i./cwt or 1,200 

mg a.i./kg seed), are calculated as follows:

RQ = Exposure (mg a.i./kg seed) / NOAEC (mg/kg diet)

The resulting RQ values exceed the Agency’s LOC for chronic risk to birds and mammals (RQ > 

1) by factors of 4 and 12, respectively (Table 4.2). For birds, this screening calculation indicates 

that a bird that consumes 1 kg of treated seed over an unspecified time period will have been 

exposed to a dietary concentration of boscalid that is 4 times the chronic NOAEC. Similarly, a 

mammal that consumes 1 kg of treated seed will have been exposed to a dietary concentration of 

boscalid that is 12 times the chronic NOAEC. The amount of time it would take a small bird or 

mammal to consume 1 kg of seed would depend upon the physiology, life history, and energy 

requirements of the individual.
-Page 24 of 52-

For terrestrial plants, RQ values are calculated based on the most sensitive toxicity endpoints 

from the submitted seedling emergence test, but not from the vegetative vigor test, because foliar 

exposure of non-target plants is considered unlikely to result from the proposed seed treatment 

use (Table 4.2). RQ values for listed monocots and for listed and nonlisted dicots are all <0.1 

and therefore are below the Agency’s LOC (RQ>1). RQ values are not calculated for risk to 

non-listed monocot plants because the IC25 value for monocots is outside the range of 

concentrations tested. 

Table 4.2. RQ values for birds, mammals, and terrestrial plants exposed to boscalid residues following seed 

treatment use on rapeseed, based on seeding rate for canola.

Use

App

Rate

lbs a.i.

/A

(#app)

App 

Method

EECs Toxicity Endpoints RQ Values

Spatial

(mg a.i.

/ft2)

Nagy 

Dose

(mg a.i.

/kg-bw

/d)

Chronic 

(mg a.i.

/kg seed)

Animals Acute Chronic

Canola 0.012

(1)

Seed 

Treatment 0.13

304 1,200

Birds

LD50>2,000 mg/kg-bw

LC50>5,000 mg/kg diet

NOAEC=300 mg/kg diet

NOAEL=25 mg/kg-bw

NA1 4.03

254 1,200

Mammals

LD50>5,000 mg/kg-bw

NOAEC=100 mg/kg diet

NOAEL=11.2 mg/kg-bw

NA1 123

Runoff (lbs a.i./A) Plants Listed Nonlisted

Canola 0.012

(1)

Seed 

Treatment

Dry Areas

<0.001

Monocot

IC25 > 0.576

NOAEL = 0.275

<0.1 NA2

Dicot

IC25 = 0.44

NOAEL = 0.275

<0.1 <0.1

Semi-Aquatic Areas

0.001 

Monocot

IC25 > 0.576

NOAEL = 0.275

<0.1 NA2

Dicot

IC25 = 0.44

NOAEL = 0.275

<0.1 <0.1

1

 RQ values for acute risk to birds and mammals are not calculated because the most sensitive acute toxicity endpoints (LD50) 

are greater than the tested limit dose.

2

 RQ values for risk to nonlisted species of terrestrial monocot plants are not calculated because the most sensitive toxicity 

endpoint (IC25) is a nondefinitive value that is greater than the highest concentration tested. 3

Exceeds chronic risk LOC (RQ>1.0) NA Not available.

Although the Agency does not typically quantify risk to non-target terrestrial invertebrates using 

the RQ method, acute toxicity studies with the young adult honey bee (Apis mellifera) indicate 

that boscalid is practically non-toxic to young adult honey bees on an acute oral and an acute 

contact exposure basis (LD50 >11 μg a.i./bee). 
-Page 25 of 52-

The potential for risk to non-target aquatic and terrestrial organisms, associated with the 

proposed use of boscalid as a seed treatment on rapeseed, is discussed further in the Risk 

Description (Section 4.2).

4.2. Risk Description and Conclusions

Boscalid is a synthetic carboxamide fungicide (FRAC Group 7) that inhibits mitochondrial 

respiration and the subsequent production of ATP in fungal cells, which inhibits spore 

germination, mycelial growth, and sporulation of the fungus on the surface of leaves (proposed 

label and Wharton 2010). Boscalid is persistent, is stable to most environmental degradation and 

plant metabolism processes, and has demonstrated at least some systemic activity. This 

assessment evaluates the potential for ecological risks associated with the proposed new use of 

boscalid as a seed treatment on rapeseed, including canola. The end-use product (Coronet®

Fungicide) in the petition includes two active ingredients (18.0% boscalid and 9.0% 

pyraclostrobin); however, risk estimation in this assessment (Section 4.1) focuses on potential 

effects associated with boscalid alone. Where available, information about similarly formulated 

end-use products is included in the discussion of incident reports.

4.2.1. Aquatic Organisms

The proposed use of boscalid as a seed treatment on rapeseed, including canola, results in acute 

and chronic surface water EECs that are at least two orders of magnitude lower than EECs for 

the most recently assessed uses on alfalfa and citrus (DP Barcode D363523). Therefore, despite 

uncertainties regarding the toxicity of boscalid to some aquatic organisms at concentrations near 

its limit of solubility in water, the likelihood of adverse effects to aquatic organisms is expected 

to be low, based on the low potential for surface water exposure following the proposed seed 

treatment use. Acute and chronic RQ values are <0.01 and are therefore far below the listed and 

non-listed species acute (RQ>0.05) and chronic risk (RQ>1.0) LOCs for all assessed aquatic 

organisms. Risk to listed and nonlisted aquatic plants is not expected to exceed the Agency’s 

LOC (RQ > 1). 

The potential for risk to benthic organisms exposed to pore water is also considered, using the 

conservative assumption that the highest concentration tested in the amphipod study represents 

the endpoint (i.e., acute: EC50 = 1.066 mg a.i./L pore water; Table 4.3). In this estimation, the 

RQ value for acute risk to benthic invertebrates (RQ<0.01) is similar to the RQ values for fish 

and invertebrates in the water column, and it does not exceed the listed or non-listed species 

LOCs.
-Page 26 of 52-

Table 4.3. RQ value calculated from the non-definitive endpoint for benthic freshwater invertebrates, based 

on mean measured pore water concentrations in a spiked sediment study with the amphipod.

Use

Application 

Rate

lbs a.i./A

(#app)

Application 

Method

EEC

(μg/L)

Characterization

Benthic Invertebrate RQ

EC50 > 1.066 mg a.i./L

Peak Acute

Canola 0.012

(1)

Seed 

Treatment 0.71 0.001

In addition to potential surface water exposure, aquatic and amphibious organisms may be 

exposed to ground water through ground water discharge into surface systems or in unique and 

sensitive ground water ecosystems, such as caves, montane gravels, etc. Because boscalid has 

moderate mobility to ground water and degrades only slowly, primarily through aerobic soil 

metabolism, estimated concentrations in shallow ground water were calculated (see Table 4.4). 

Estimated concentrations of boscalid residues in ground water (EEC=0.01 μg/L) are lower than 

estimated concentrations in surface water (EEC=0.72 μg/L). Therefore, adverse effects to 

aquatic organisms exposed to boscalid residues in ground water are unlikely.

Table 4.4 RQ values for aquatic animals exposed to boscalid residues in shallow ground water.

Use

App

Rate

lbs a.i./A

(#app)

App 

Method

EECs

(μg/L) Toxicity Endpoints Ground WaterRQ Values

Peak 21-d 60-d Aquatic Animals Acute Chronic

Canola 0.012

(1)

Seed 

Treatment 0.01 0.01 0.01

Freshwater Fish

LC50=2.7 mg/L

NOAEC=0.116 mg/L

<0.001 <0.001

Freshwater Invertebrate 

EC50=NA

NOAEC=0.79 mg/L

NA1 <0.001

1

 An acute freshwater invertebrate study was submitted (MRID 45405001); however, the results are not used in 

quantitative risk estimation because they may underestimate toxicity (see DP Barcode 363523 for discussion). 

Potential acute risks to freshwater invertebrates are discussed as part of the Risk Description (Section 4.2).

App Application. NA Not available.

Finally, laboratory tests resulted in a maximum bioconcentration factor (BCF) of 105x 

(nonedible tissues of rainbow trout) under test conditions. Boscalid in fish tissues depurated 

rapidly after exposure ceased, with a modeled half-life of 0.8 – 1 days. Sublethal behavioral 

effects (lethargy and loss of equilibrium) were noted during the study and physiological effects 

(darkened livers and gall bladders and a discolored gastrointestinal tract) were noted at necropsy 

in fish exposed to boscalid at 200 μg/L. Sublethal effects (lethargy, narcosis, and extended yolk 

sacs) were observed at a similar concentration (241 μg a.i./L) in the early life stage test with 

rainbow trout, beginning approximately one week after termination of hatch (day 35). However, 

the concentrations associated with chronic effects in both studies are far greater than chronic 

EECs for the proposed new use of boscalid (0.72 μg a.i./L in surface water, 0.01 μg a.i./L in 

ground water).
-Page 27 of 52-

4.2.2. Terrestrial Organisms

Although the available data indicate that the likelihood for adverse effects on aquatic organisms 

as a result of the proposed new use of boscalid as a seed treatment on rapeseed is very low, 

greater uncertainty surrounds the potential for risk to terrestrial organisms. Acute RQ values are 

not calculated in the Risk Estimation for birds and mammals because the necessary toxicity 

endpoints (LD50/LC50) were determined to be greater than the limit dose in the submitted studies. 

Therefore, although boscalid is classified as practically non-toxic to birds and mammals on an 

acute exposure basis, the nature and potential dose-response relationship of any effects of 

boscalid at exposure levels above the limit dose are unknown. The potential for acute risk is 

characterized in Table 4.5, using the conservative assumption that the limit dose represents the 

toxicity endpoint (LD50), which is then adjusted for the body weight (bw) of the test specimens 

(default bw=178 g for bobwhite quail, 350 g for Norway rat) and compared to the estimated 

exposure per unit area (mg a.i./ft2) and per daily dose of treated seed (i.e., Nagy dose; mg a.i./kg 

bw/day). 

Table 4.5. Characterization of potential risk to terrestrial birds and mammals, assuming that the limit dose 

tested in effects studies is the definitive toxicity endpoint.

Use

App

Rate

lbs a.i.

/A

(#app)

App 

Method

EECs Toxicity Endpoints

Characterization 

Terrestrial

RQ Values

Spatial

(mg a.i./ft2)

Nagy Dose

(mg a.i./kg-bw

/d)

Animals Acute

Spatial

Acute

DoseBased

Canola 0.012

(1)

Seed 

Treatment 0.13

304

Birds

LD50>2,000 mg/kg-bw

LC50>5,000 mg/kg diet

NOAEC=300 mg/kg diet

NOAEL=25 mg/kg-bw

0.21 <0.01

254

Mammals

LD50>5,000 mg/kg-bw

NOAEC=100 mg/kg diet

NOAEL=11.2 mg/kg-bw

0.02 <0.01

The available data indicate that acute risk to mammals is unlikely to exceed the Agency’s LOC. 

No mortality was observed in any of the submitted limit dose tests, and boscalid is not expected 

to cause frank mortality in birds. However, acute risk of sublethal effects to listed species of 

birds (and therefore to listed reptiles and terrestrial-phase amphibians) cannot be precluded. The 

Agency’s LOC for acute risk to listed species of birds is based on the determination that the 

LD50/ft2 value is at least 10 times greater than the EEC (i.e., LOC = 0.1). However, the 

submitted limit tests only establish that the LD50/ft2 value for bobwhite quail is at least five times 

greater than the spatial EEC for the proposed new use as a seed treatment on rapeseed. This 

uncertainty, coupled with the absence of data for acute effects on passerine birds, results in an 

incomplete understanding of the potential effects of boscalid exposure from seed treatment uses 

on avian species.

The low potential for acute risk to listed species of birds can be further characterized by 

considering how foraging ecology affects the potential for exposure. To consume a mass of 
-Page 28 of 52-

boscalid equivalent to the limit dose in the submitted study with bobwhite quail, a 20-g bird 

would have to consume 28.8 mg a.i., equivalent to 24 g (0.053 lbs) of rapeseed treated at the 

maximum proposed application rate (0.12 lbs a.i./cwt). This is considered an unlikely, though 

not impossible, scenario for most species. Smaller, migrating birds that eat seeds are expected to 

be at the highest risk of exposure, since they have higher surface area-to-body weight ratios and 

they must rapidly refuel energy reserves exhausted during migration (Klassen & Lindstrom 

1996). In a short period of time (e.g., one day or less), these birds may consume larger amounts 

of seeds, relative to body size, in proportions that approach or exceed their own body weight. 

Nonetheless, given that no adult mortality was observed in avian tests, frank mortality would be 

unlikely to result if a bird did consume the large amount of rapeseed necessary to be exposed to 

the limit dose.

As the foraging efficiency of a seed predator (granivore) decreases, the area of exposure (i.e., 

treated field) necessary to trigger the LOC increases. For example, assuming conservatively that 

the limit dose in the submitted studies represents the LD50 value for birds, a 20-g, seed-eating 

bird with 100% foraging efficiency (i.e., that eats all seeds within a given area) would consume 

enough boscalid in a 23-ft2 area to exceed the Agency’s LOC for listed species of birds. Using 

the same assumption, a 20-g bird would consume enough boscalid to trigger the acute risk LOC 

for listed birds if it displayed 50% foraging efficiency in a 46-ft2 foraging area, or if it displayed 

10% foraging efficiency within a 231-ft2 foraging area. The actual foraging area necessary to 

result in mortality to birds at a level equivalent to an LD50 (i.e., mortality of 50% of exposed 

birds) is likely much greater given that no mortality was observed at the limit dose.

As with birds and mammals, acute laboratory tests with terrestrial invertebrates (i.e., honey bee) 

have demonstrated no adverse effects to young adults exposed to boscalid at the limit dose. 

However, multiple ecological incidents have been reported wherein boscalid use was associated 

with adverse effects on managed honey bees (see Section 3.3.2). Bee keepers have reported 

adverse honey bee brood effects, particularly following the use of the formulated product 

Pristine® (25.2% boscalid and 12.8% pyraclostrobin) on almonds (BASF 2008, US EPA 2010), 

which require active pollination by managed honey bees or other pollinators. The maximum 

single application rate for the proposed seed treatment use of boscalid on rapeseed (0.012 lbs 

a.i./A) is much lower than the maximum labeled rate for use on almonds (0.234 lbs a.i./A, 

Pristine®); additionally, the difference in application method (i.e., foliar spray to almonds versus 

seed treatment to rapeseed) suggests a reduced potential for honey bee exposure for the proposed 

new use. Although boscalid demonstrates some systemic activity, the extent to which the 

compound may be translocated to nectar and pollen from a treated seed is unknown. Exposure 

of ground-nesting bees and wasps may be more likely than exposure of honey bees, given that 

the compound is expected to persist in soil and on organic matter.

Following another incident of adverse effects on honey bees, not yet verified by EPA, residue 

analysis confirmed the presence of boscalid (149 ng a.i./g wax) and pyraclostrobin (141 ng a.i./g 

wax) in hive samples (Stone 2010). Multiple other pesticides were also detected. Unlike the 

previous incidents, both adult bee mortality and hive effects were reported, and the report 

indicated that pesticide misuse may have occurred. Nonetheless, boscalid residues detected in 

the samples were at the upper bound of the laboratory’s historical boscalid detection range (16.9 
-Page 29 of 52-

– 154 ng a.i./g wax) and were considerably higher than the average residue level (70.4 ng a.i./g 

wax) detected in laboratory samples through 2008.

Finally, the proposed new use of boscalid as a seed treatment is not expected to result in risk to 

non-target terrestrial plants exposed through runoff from a field where treated seeds are planted. 

RQ values for listed plants (monocots and dicots) and for nonlisted dicot plants are less than 0.1, 

and potential risk to nonlisted monocot plants is not expected to exceed risk to listed monocot 

plants. However, the proposed new use is on a Brassica crop (rapeseed), and the most sensitive 

terrestrial plant in both seedling emergence and vegetative vigor tests was also a Brassica species

(cabbage). Risk estimates are not calculated for labeled crop species, but the potential adverse 

effects on Brassica sp. emergence would not be expected to trigger concern (LOC = 1) for crop 

species because the calculated application rate (0.012 lbs a.i./A) is less than one-twentieth of the 

seedling emergence NOAEC value (0.275 lbs a.i./A).

4.2.3. Conclusions

The physico-chemical properties of boscalid indicate that the fungicide has a moderate potential 

to reach aquatic environments, including surface and ground water, for several months or more 

following application of treated seeds. Although the available ecotoxicity data demonstrate that 

boscalid is acutely toxic to aquatic organisms and may cause chronic effects, including effects 

linked to reproduction and sublethal behavioral effects in some aquatic test species, the aquatic 

exposure levels (EECs) that result from the proposed new use as a seed treatment on rapeseed are 

relatively low. Therefore, the potential for direct acute or chronic effects on aquatic organisms, 

including fish, aquatic invertebrates, aquatic-phase amphibians, and aquatic plants is low.

Terrestrial vertebrates may be exposed to boscalid by contact with or ingestion of treated 

rapeseed. Seed-eating (granivore) birds and mammals may be exposed to boscalid as a result of 

the seed treatment use. This assessment concludes that the proposed new use of boscalid as a 

seed treatment on rapeseed will result in chronic risk to mammals, birds, reptiles, terrestrialphase amphibians, and mammals that exceeds the Agency’s LOC. Acute risk to mammals and to 

non-listed birds, reptiles, and terrestrial-phase amphibians does not exceed the Agency’s LOC. 

Likewise, risk to non-target terrestrial and semi-aquatic plants does not exceed the LOC.

The submitted avian tests show that boscalid is practically non-toxic to birds at the limit dose on 

an acute exposure basis. However, uncertainty surrounds the potential for adverse effeects in 

listed species of birds because (1) the avian toxicity tests did not establish whether effects might 

occur at threshold exposure levels (higher than the limit dose) for listed species determinations 

(i.e., ten times the EEC for the proposed new use), (2) sublethal effects were observed in one 

subacute dietary study, and (3) no data have been submitted for potentially sensitive passerine 

species. Therefore, acute risk of sublethal effects in listed species of birds, and therefore in listed 

species of reptiles and terrestrial-phase amphibians, cannot be precluded. Nonetheless, the 

absence of mortality at the limit dose suggests that frank mortality is unlikely, and no ecological 

incidents with birds have been reported for boscalid.

This assessment does not assess risk to terrestrial invertebrates. However, ecological incidents 

of adverse effects on honey bees indicate a potential for adverse effects to terrestrial 
-Page 30 of 52-

invertebrates. The effects on honey bee brood reported in several incidents would not be 

captured in current guideline toxicity studies with young adult honey bees. 

5. Federally Threatened and Endangered (Listed) Species of Concern

Section 7 of the Endangered Species Act, 16 U.S.C. Section 1536(a)(2), requires all federal

agencies to consult with the National Marine Fisheries Service (NMFS) for marine and 

anadromous listed species, and the United States Fish and Wildlife Service (USFWS) for listed 

wildlife and freshwater organisms, if they are proposing an "action" that may affect listed species 

or their designated critical habitat. Each federal agency is required under the Act to ensure that 

any action it authorizes, funds, or carries out is not likely to jeopardize the continued existence of 

a listed species or result in the destruction or adverse modification of designated critical habitat. 

To jeopardize the continued existence of a listed species means "to engage in an action that 

reasonably would be expected, directly or indirectly, to reduce appreciably the likelihood of both 

the survival and recovery of a listed species in the wild by reducing the reproduction, numbers, 

or distribution of the species" (50 C.F.R. § 402.02).

To facilitate compliance with the requirements of the Endangered Species Act (subsection 

(a)(2)), the Office of Pesticide Programs has established procedures to evaluate whether a 

proposed registration action may directly or indirectly appreciably reduce the likelihood of both 

the survival and recovery of a listed species in the wild by reducing the reproduction, numbers, 

or distribution of any listed species (USEPA 2004). After the Agency’s screening level risk 

assessment is conducted, if any of the Agency’s listed species LOCs are exceeded for either 

direct or indirect effects, an analysis is conducted to determine if any listed or candidate species 

may co-occur in the area of the proposed pesticide use or areas downstream or downwind that 

could be contaminated from drift or runoff/erosion. If listed or candidate species may be present 

in the proposed action area, further biological assessment is undertaken. The extent to which 

listed species may be at risk is considered, which then determines the need for the development 

of a more comprehensive consultation package, as required by the Endangered Species Act.

The federal action addressed herein is the proposed registration of a new use for boscalid as a 

seed treatment on rapeseed, including canola. It is expected that the new uses of boscalid could 

occur nationwide; however, according to the USDA National Agricultural Statistics Service 

(NASS) 2007 census, the proposed new seed treatment uses for canola are likely to 

predominantly occur in the states of North Dakota, Minnesota, Idaho, and Washington (USDA 

2009; www.agcensus.usda.gov; searched on 25 October 2010). Based on the reported crop 

acreage harvested per state, other varieties of rapeseed are expected to be grown primarily in 

Idaho, Oregon, and Washington (USDA 2009).

5.1. Action Area

For listed species assessment purposes, the action area is considered to be the area affected 

directly or indirectly by boscalid use and not merely the immediate area where boscalid is 

applied. At the initial screening-level, the risk assessment considers broadly described 

taxonomic groups and conservatively assumes that listed species within those broad groups are 
-Page 31 of 52-

co-located with the pesticide treatment area. This means that terrestrial plants and wildlife are 

assumed to be located on or adjacent to the treated site and aquatic organisms are assumed to be 

located in a surface water body adjacent to the treated site. The assessment also assumes that the 

listed species are located within an assumed area, which has the relatively highest potential 

exposure to the pesticide, and that exposures are likely to decrease with distance from the 

treatment area. Section 5.2 of this risk assessment presents the proposed pesticide use sites that 

are used to establish initial co-location of species with treatment areas.

5.2. Taxonomic Groups Potentially at Risk

If the assumptions associated with the screening-level action area result in RQs that are below 

the listed species LOCs, a "no effect" determination conclusion is made with respect to listed 

species in that taxa, and no further refinement of the action area is necessary. Furthermore, RQs 

below the listed species LOCs for a given taxonomic group indicate no concern for indirect 

effects on listed species that depend upon the taxonomic group for which the RQ was calculated. 

However, in situations where the screening assumptions lead to RQs in excess of the listed 

species LOCs for a given taxonomic group, a potential for a "may affect" conclusion exists and 

may be associated with direct effects on listed species belonging to that taxonomic group or may 

extend to indirect effects upon listed species that depend upon that taxonomic group as a 

resource. In such cases, additional information on the biology of listed species, the locations of 

these species, and the locations of use sites are considered to determine the extent to which 

screening assumptions regarding an action area apply to a particular listed organism. These 

subsequent refinement steps will consider how this information would impact the action area for 

a particular listed organism and potentially include areas of exposure that are downwind and 

downstream of the pesticide use site.

Assessment endpoints, exposure pathways, the conceptual models addressing the proposed new 

boscalid use, and the associated exposure and effects analyses conducted for the boscalid

screening-level risk assessment are in Sections 2 to 3. The assessment endpoints used in the 

screening-level risk assessment include those defined operationally as reduced survival and 

reproductive impairment for both aquatic and terrestrial animal species and survival, 

reproduction, and growth of nontarget aquatic and terrestrial plant species from exposure via 

runoff. These assessment endpoints address the standard set forth in the Endangered Species Act 

requiring federal agencies to ensure that any action it authorizes does not appreciably reduce the 

likelihood of both the survival and recovery of a listed species in the wild by reducing the 

reproduction, numbers, or distribution of the species. Risk estimates (RQ values) integrating 

exposure and effects are calculated for broad-based taxonomic groups in the screening-level risk 

assessment and are presented in Section 4.

Both acute listed species and chronic risk LOCs are considered in the screening-level risk 

assessment to identify direct and indirect effects to taxa of listed species. This section identifies 

direct and indirect effect concerns, by taxa, that are triggered by exceeding listed LOCs in the 

screening-level risk assessment (Table 5.1). When applicable, probit dose response analysis to 

used to evaluate the probability of individual acute effects for exposures that occur at the 

established listed species LOC (Section 5.2.1). Data on exposure and effects collected under 
-Page 32 of 52-

field (when available) and laboratory conditions are evaluated to make determinations on the 

predictive utility of the direct effect screening assessment findings to listed species. 

Table 5.1 Potential effects to federally listed taxa associated with the proposed new use of boscalid.

Listed Taxon Direct Effects Indirect Effects from Risk to Other Taxa

Yes/No Acute/Chronic Yes/No Through ...

Terrestrial and semiaquatic plants –

monocots and dicots

No NA Yes Acute sublethal1 and chronic effects on birds, 

chronic effects on mammals, when required 

for pollination or seed dispersal.

Birds Yes Acute sublethal1

and Chronic

Yes Chronic effects on mammals that serve as 

prey; acute sublethal1 and chronic effects on 

reptiles and amphibians that serve as prey.

Terrestrial-phase 

amphibians

Yes Acute sublethal1

and Chronic

Yes Chronic effects on mammals which provide 

critical habitat (e.g., burrows) and serve as 

prey.

Reptiles Yes Acute sublethal1

and Chronic

Yes Chronic effects on mammals that serve as 

prey; acute sublethal1 and chronic effects on 

birds, reptiles, and amphibians that serve as 

prey.

Mammals Yes Chronic Yes Acute sublethal1 and chronic effects on birds, 

reptiles, and amphibians that serve as prey; 

chronic effects on mammals that serve as 

prey. 

Aquatic plants No NA No NA

Freshwater fish No NA No NA

Aquatic-phase 

amphibians

No NA Yes Acute sublethal1 and chronic effects on 

terrestrial-phase amphibians.

Freshwater invertebrates No NA No NA

Molluscs No NA No NA

Marine/estuarine fish No NA No NA

Marine/estuarine 

invertebrates

No NA No NA

NA Not applicable. 1 Acute risk of sublethal effects in listed species of birds, and therefore in reptiles and terrestrial-phase amphibians, 

could not be precluded based on the submitted ecotoxicity data.

5.2.1. Probit Dose-Response Analysis

The Agency uses the probit dose-response relationship as a tool for providing additional 

information on the potential for acute direct effects to individual listed species and to terrestrial 

and aquatic animals that may indirectly affect the listed species of concern (USEPA 2004). 

However, the proposed new use of boscalid as a seed treatment on rapeseed results in RQ values 

that do not exceed the Agency’s LOC for acute risk to listed species of freshwater fish or 

estuarine/marine molluscs. Despite uncertainties in the ecotoxicity profile of boscalid, the 

available data further indicate that acute risk to mammals and other aquatic organisms is not 

expected to exceed the Agency’s LOC for listed or nonlisted species. Although acute risk of 

sublethal effects in listed species of birds, and therefore in listed reptiles and terrestrial-phase 
-Page 33 of 52-

amphibians, cannot be precluded, probit dose-response analysis is not conducted for these taxa 

because no mortality was observed at the limit dose in the submitted acute avian studies. 

Potential risks to listed species of birds and to other taxa are characterized in Section 4.2

(above).

5.2.2. Listed Species Occurrence with Proposed New Use of Boscalid

A preliminary analysis of the co-occurrence of listed species and the proposed new uses of 

boscalid was conducted using OPP’s LOCATES database (v. 2.10.4). The goal of the analysis 

for co-location is to determine whether sites of pesticide use are geographically associated with 

known locations of listed species. The objective is to provide insight into the potential for 

exposure of listed species and to identify those areas, crop uses, and listed species that warrant 

further attention. The LOCATES database uses location information for listed species at the 

county level and compares it to agricultural census data (from 2002) for crop production at the 

same county level of resolution. The product is a listing of federally-listed species that are 

located within counties known to produce the crops upon which the pesticide will be used. 

Appendix H provides a species listing by state for those listed species that may potentially be 

impacted by the proposed new uses of boscalid.

A tabulation of the number of unique listed species in each state that may co-occur with the 

proposed new use of boscalid as a seed treatment on rapeseed is provided in Table 5.2. 

Although this assessment does not evaluate risk to terrestrial invertebrates, adverse effects on 

honeybees, associated with the use of boscalid, have been reported. Terrestrial invertebrates are 

included in the tabulation of species that may co-occur with areas of boscalid use. Secondary 

effects may occur in predatory birds, reptiles, amphibians, and mammals that rely on mammals, 

birds, reptiles, or terrestrial amphibians as prey. LOCATES does not currently differentiate 

between different feeding guilds or identify those plant species that require particular interactions 

for pollination or seed dispersal. Therefore, the number of potentially affected listed mammals, 

birds (also reptiles and terrestrial-phase amphibians), and terrestrial plants may be overestimated 

and include species that are not likely to be indirectly affected if they do not (1) rely on 

mammals, birds, amphibians, reptiles, or seeds as prey or (2) require mammals or birds for 

pollination or seed dispersal. Additionally, in cases where a listed amphibian species with an 

aquatic phase does not also have a terrestrial phase or use terrestrial habitat, the number of 

potentially affected amphibian species may be overestimated.

Based the results of the LOCATES database query, there are a total of 123 listed species of 

terrestrial plants, birds, reptiles, terrestrial and aquatic-phase amphibians, mammals, and 

terrestrial invertebrates associated with counties where boscalid may be used nationwide on

rapeseed, including canola. It is expected that the actual total number of potentially affected 

listed species would be less than 123 because there are redundancies where a given species is 

listed in more than one state. A total of 23 states have listed species that are potentially affected 

by direct or secondary effects of boscalid exposure and are associated with rapeseed crops where 

boscalid may be used. California has the highest number (25) of listed species in the identified 

taxa that may co-occur with the proposed boscalid uses on rapeseed, followed by Oregon (12), 

Michigan (11) and Georgia (10).
-Page 34 of 52-

This preliminary analysis indicates that there is a potential for boscalid use to overlap with listed 

species and that a more refined assessment is warranted. The more refined assessment should 

involve clear delineation of the action area associated with proposed uses of boscalid and the 

best available information on the temporal and spatial co-location of listed species with respect 

to the action area. This analysis has not been conducted for this screening level assessment.

Table 5.2. Tabulation by state and taxonomic group of listed species at potential risk of direct or secondary 

effects of boscalid use as a seed treatment, in areas where rapeseed (including canola and crambe) is grown.

State

AmphibiansAquatic MammalsBirdsCrustaceansDicot PlantsFernsOther InvertebratesMammalsMonocot Plants

ReptilesTotal per State

Alabama 1 2 2 5

Alaska 0

Arizona 0

Arkansas 1 1

California 2 1 2 11 1 4 1 3 25

Colorado 2 1 2 1 6

Connecticut 0

Delaware 0

Florida 0

Georgia 2 2 3 1 1 1 10

Hawaii 0

Idaho 1 3 2 2 8

Illinois 1 1

Indiana 1 1

Iowa 0

Kansas 3 1 1 5

Kentucky 1 2 3

Louisiana 0

Maine 1 1 1 3

Maryland 0

Massachusetts 0

Michigan 2 3 2 2 2 11

Minnesota 1 1 1 3

Mississippi 0

Missouri 0

Montana 3 1 2 6

Nebraska 0

Nevada 0

New Hampshire 0

New Jersey 0

New Mexico 0

New York 0

North Carolina 1 1 2

North Dakota 3 1 4

Ohio 1 1 2

Oklahoma 0

Oregon 3 7 2 12
-Page 35 of 52-

State

AmphibiansAquatic MammalsBirdsCrustaceansDicot PlantsFernsOther InvertebratesMammalsMonocot PlantsReptilesTotal per State

Pennsylvania 1 1

Rhode Island 0

South Carolina 0

South Dakota 3 1 1 5

Tennessee 0

Texas 0

Utah 1 1

Vermont 0

Virginia 0

Washington 1 2 1 4

West Virginia 0

Wisconsin 2 1 1 4

Wyoming 0

Total Number

of Species 4 1 29 2 37 1 9 26 10 4 123

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December 2009. Available online at http://www.agcensus.usda.gov.

-- 2006. Crop profile for citrus (major) oranges/grapefruit in Florida. Available online at 

http://www.ipmcenters.org/cropprofiles/docs/FLcitrus(major).pdf.

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http://www.ipmcenters.org/cropprofiles/docs/txalfalfa.pdf.

-- 2000. Crop profile for alfalfa in Minnesota. Available online at 

http://www.ipmcenters.org/cropprofiles/docs/mnalfalfa.pdf.

-- 2000. Crop profile for canola in Minnesota. Available online at 

http://www.ipmcenters.org/cropprofiles/docs/mncanola.pdf.

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http://countrystudies.us/united-states/weather/florida/west-palm-beach.htm.

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Boscalid New Uses on Alfalfa and Citrus (Group 10). DP 363523. Environmental Fate and Effects 

Division, Office of Pesticide Programs, Washington, D.C.

-- 2003. BAS 510F in/on Various Plant and Animal Commodities. HED Metabolism Assessment Review 

Committee (MARC) Decision Memo. PP# 1F06313. Memo from Maxie Jo Nelson, Henri Bietlot and Alan 

Levy to Yan Donovan. 9 January 2003. Office of Pesticide Programs, Washington, D.C.

-- 2010b. Boscalid Section 3: Environmental Fate and Ecological Risk Assessment for the Proposed New Uses on 

Alfalfa and Citrus (Group 10). DP 363523. Memo from Catherine Aubee and David Lieu to Bryant Crowe 

and Tony Kish. 19 February 2010. Office of Pesticide Programs, Washington, D.C.

-- 2009a. Pesticides; Data Requirements for Conventional Chemicals, Technical Amendments, and Data 

Requirements for Biochemical and Microbial Pesticides; Final Rule. FR 72(207):60933-60988.

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-- 2009c. ECOTOXicology Database, v. 4.0. Accessed on 16 November 2009. Available online at 

http://cfpub.epa.gov/ecotox/.

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http://www.epa.gov/pesticides/science/models_db.htm.

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Washington, D.C. Available online at 

http://www.epa.gov/oppefed1/models/water/input_parameter_guidance.htm

-- 2008. Science Advisory Panel (SAP): Selected Issues Associated with the Risk Assessment Process for Pesticides 

with Persistent, Bioaccumulative, and Toxic Characteristics. Office of Prevention, Pesticides and Toxic 

Substances, Office of Pesticide Programs, Washington, D.C. 

-- 2004. Overview of the Ecological Risk Assessment Process in the Office of Pesticide Programs, U.S. 

Environmental Protection Agency. Endangered and Threatened Species Effects Determinations. Office of 

Prevention, Pesticides and Toxic Substances, Office of Pesticide Programs, Washington, D.C. Available 

online at http://www.epa.gov/oppfead1/endanger/consultation/ecorisk-overview.pdf.

-- 2003. Environmental Fate and Ecological Risk Assessment for the Registration of BAS 510 F (Nicobifen). DP 

Barcodes D278387, D278390, D278418. Environmental Fate and Effects Division, Office of Pesticide 

Programs, Washington, D.C.

-- 1998. Guidelines for Ecological Risk Assessment. EPA/630/R-95/002F. Published in 63 FR 26846; May 14, 

1998. U.S. Environmental Protection Agency, Washington, DC. April, 1998.

-- 1993. Wildlife Exposure Factors Handbook. EPA/600/R-13/187a. Office of Research and Development, 

Washington, D.C.

Van Engelsdorp, D., J.D. Evans, C. Saegerman, C. Mullin, E. Haubruge, B.K. Nguyen, M. Frazier, J. Frazier, D. 

Cox-Foster, Y. Chen, R. Underwood, D.R. Tarpy, and J.S. Pettis. 2009. Colony collapse disorder: A 

descriptive study. PloS ONE 4 (8): e6481.

Van Engelsdorp, D., and M.D. Meixner. 2010. A historical review of managed honey bee populations in Europe 

and the United States and the factors that may affect them. Journal of Invertebrate Pathology 103: S80 -

S95.

Wharton, P.S., Michigan State University. May 1, 2010. Michigan Potato Diseases website. Available online at 

http://www.potatodiseases.org/pdf/Fungicide-Resistance-Management.pdf

Willis, G.H. and L.L. McDowell. 1987. Pesticide persistence on foliage. Reviews of Environmental 

Contamination and Toxicology 100: 23-73.

Wilson, C., B. Boman, E. Stover, J. Bargar, and J. Hebb. 2006. Flatwoods citrus Best Management Practice: 

Minimizing direct deposition of pesticides into waterways. SL235. Institute of Food and Agricultural 

Sciences, University of Florida, Gainesville, FL. Available online at 

http://edis.ifas.ufl.edu/pdffiles/SS/SS45400.pdf. 
-Page 38 of 52-

Appendix A. Chemical names and structures of boscalid and its degradates

IUPAC Name: 2-chloro-N-(4’-chlorobiphenyl2-yl)-nicotinamide

CAS Name: 2-chloro-N-(4’-chloro[1,1-

biphenyl-2-yl)-3-pyradinecarboxamide

CAS Number: 188425-85-6

Synonyms: 2-chloro-N-(4’-chlorobiphenyl-2-

yl)-nicotinamide, BAS 510 F, boscalid, 

nicobifen

M510F47 2-chloronicotinic acid-[pyridine3-

14C]

M510F49 (2-hydroxy-N-(4’-chlorobiphenyl2-yl)-nicotonamide)

[Diphenyl-U14C]-labeled BAS 510 F M510F64 (p-chloro-benzoic acid)

[Pyridine-3-

14C]-labeled BAS 510 F M510F50 Unknown 2
-Page 39 of 52-

Appendix B. PRZM/EXAMS file names and sample input/output data 

PRZM/EXAMS file names 

Electronic files available as a compressed attachment.

Surface water: NDcanolaSTD.out

Benthic segment: NDcanolaSTDben.out

PRZM and EXAMS sample input/output data for broadcast application of treated seeds 

adjacent to the Standard Farm Pond

Chemical: Boscalid

PRZM environment: NDcanolaSTD.txt modified Tueday, 26 August 2008 at 06:16:40

EXAMS environment: pond298.exv modified Tueday, 26 August 2008 at 06:14:08

Metfile: w24013.dvf modified Tueday, 26 August 2008 at 06:15:40

Water segment concentrations (ppb)

Year Peak 96 hr 21 Day 60 Day 90 Day Yearly

1961 0.002435 0.002394 0.00225 0.002047 0.001959 0.0009865

1962 0.04269 0.04193 0.03977 0.03774 0.03626 0.0219

1963 0.08478 0.08401 0.08071 0.07654 0.07611 0.05823

1964 0.1538 0.1521 0.1474 0.1439 0.1422 0.1135

1965 0.1587 0.1584 0.1575 0.1565 0.1562 0.1485

1966 0.1886 0.1877 0.1845 0.1802 0.1791 0.1697

1967 0.195 0.1945 0.1929 0.1905 0.1894 0.1845

1968 0.2385 0.2376 0.2344 0.2299 0.2279 0.2091

1969 0.2378 0.2374 0.2363 0.2343 0.2333 0.2281

1970 0.2849 0.2839 0.2811 0.2762 0.274 0.256

1971 0.3759 0.3737 0.366 0.3583 0.3543 0.3049

1972 0.3418 0.3417 0.3414 0.3409 0.3408 0.3397

1973 0.3644 0.3639 0.362 0.3607 0.3596 0.3481

1974 0.3998 0.3988 0.395 0.3904 0.3879 0.3734

1975 0.4303 0.4291 0.4266 0.4245 0.4238 0.4054

1976 0.4281 0.4279 0.427 0.4261 0.4254 0.4229

1977 0.5001 0.4986 0.4941 0.487 0.4857 0.4628

1978 0.5313 0.5301 0.5273 0.5215 0.5205 0.5046

1979 0.5706 0.5691 0.5639 0.5562 0.5527 0.5341

1980 0.5803 0.5791 0.5752 0.5738 0.5737 0.5545

1981 0.5856 0.5851 0.5834 0.5807 0.5805 0.5741

1982 0.6265 0.6261 0.6242 0.6215 0.62 0.599

1983 0.6404 0.64 0.6387 0.637 0.6357 0.6233

1984 0.6986 0.6975 0.6913 0.6821 0.6777 0.6571

1985 0.717 0.7157 0.7116 0.7087 0.7084 0.6919

1986 0.7165 0.7162 0.7148 0.7134 0.7125 0.7092

1987 0.7946 0.7922 0.7836 0.7713 0.766 0.7302

1988 0.7568 0.7564 0.7554 0.7538 0.7526 0.7502

Sorted results

Prob. Peak 96 hr 21 Day 60 Day 90 Day Yearly

0.0344827586206897 0.7946 0.7922 0.7836 0.7713 0.766 0.7502

0.0689655172413793 0.7568 0.7564 0.7554 0.7538 0.7526 0.7302

0.103448275862069 0.717 0.7162 0.7148 0.7134 0.7125 0.7092

0.137931034482759 0.7165 0.7157 0.7116 0.7087 0.7084 0.6919
-Page 40 of 52-

0.172413793103448 0.6986 0.6975 0.6913 0.6821 0.6777 0.6571

0.206896551724138 0.6404 0.64 0.6387 0.637 0.6357 0.6233

0.241379310344828 0.6265 0.6261 0.6242 0.6215 0.62 0.599

0.275862068965517 0.5856 0.5851 0.5834 0.5807 0.5805 0.5741

0.310344827586207 0.5803 0.5791 0.5752 0.5738 0.5737 0.5545

0.344827586206897 0.5706 0.5691 0.5639 0.5562 0.5527 0.5341

0.379310344827586 0.5313 0.5301 0.5273 0.5215 0.5205 0.5046

0.413793103448276 0.5001 0.4986 0.4941 0.487 0.4857 0.4628

0.448275862068966 0.4303 0.4291 0.427 0.4261 0.4254 0.4229

0.482758620689655 0.4281 0.4279 0.4266 0.4245 0.4238 0.4054

0.517241379310345 0.3998 0.3988 0.395 0.3904 0.3879 0.3734

0.551724137931034 0.3759 0.3737 0.366 0.3607 0.3596 0.3481

0.586206896551724 0.3644 0.3639 0.362 0.3583 0.3543 0.3397

0.620689655172414 0.3418 0.3417 0.3414 0.3409 0.3408 0.3049

0.655172413793103 0.2849 0.2839 0.2811 0.2762 0.274 0.256

0.689655172413793 0.2385 0.2376 0.2363 0.2343 0.2333 0.2281

0.724137931034483 0.2378 0.2374 0.2344 0.2299 0.2279 0.2091

0.758620689655172 0.195 0.1945 0.1929 0.1905 0.1894 0.1845

0.793103448275862 0.1886 0.1877 0.1845 0.1802 0.1791 0.1697

0.827586206896552 0.1587 0.1584 0.1575 0.1565 0.1562 0.1485

0.862068965517241 0.1538 0.1521 0.1474 0.1439 0.1422 0.1135

0.896551724137931 0.08478 0.08401 0.08071 0.07654 0.07611 0.05823

0.931034482758621 0.04269 0.04193 0.03977 0.03774 0.03626 0.0219

0.96551724137931 0.002435 0.002394 0.00225 0.002047 0.001959

0.0009865

0.1 0.72098 0.72022 0.71886 0.71744 0.71651 0.7113

Average of yearly averages: 0.391997017857143
-Page 41 of 52-

Appendix C. SCI-GROW sample input/output data

SciGrow version 2.3

chemical:Boscalid on Rapeseed

time is 8/16/2010 14:58: 1

------------------------------------------------------------------------

 Application Number of Total Use Koc Soil Aerobic

 rate (lb/acre) applications (lb/acre/yr) (ml/g) metabolism (days)

------------------------------------------------------------------------

 0.012 1.0 0.012 7.16E+02 1305.0

------------------------------------------------------------------------

groundwater screening cond (ppb) = 1.02E-02 

************************************************************************

SciGrow version 2.3

chemical:Boscalid on Turf

time is 8/16/2010 14:59:15

------------------------------------------------------------------------

 Application Number of Total Use Koc Soil Aerobic

 rate (lb/acre) applications (lb/acre/yr) (ml/g) metabolism (days)

------------------------------------------------------------------------

 0.350 6.0 2.100 7.16E+02 1305.0

------------------------------------------------------------------------

groundwater screening cond (ppb) = 1.78E+00 

************************************************************************
-Page 42 of 52-

Appendix D. Example T-REX (v. 1.4.1) input and output data
-Page 43 of 52-

Appendix E. Example TerrPlant (v. 1.2.2) input and output data
-Page 44 of 52-

Appendix F. Ecotoxicity data gaps and uncertainties

Guideline

(MRID)

Study Type Classification and

Issues

72-1c

(45404927)

Acute toxicity to freshwater fish (rainbow 

trout, Oncorhynchus mykiss)

Supplemental

No measured concentrations.

72-1a

(45404928)

Acute toxicity to freshwater fish (bluegill, 

Lepomis macrochirus)

Supplemental

Water quality; uncertainty with measured 

concentrations.

72-4a

(45405006)

Early life-stage toxicity to freshwater fish 

(rainbow trout, Oncorhynchus mykiss)

Supplemental

Water quality; uncertainty with measured 

concentrations.

72-2

(45405001)

Acute toxicity to freshwater invertebrates 

(waterflea, Daphnia magna)

Supplemental

Precipitate not filtered/centrifuged; water quality; 

uncertainty with measured concentrations. Data 

not suitable for quantitative use in risk assessment.

72-4b

850.1300

(46351406)

Chronic toxicity to freshwater invertebrates 

(waterflea, Daphnia magna)

Acceptable

Use of a solvent and treatment of water samples 

not specified.

N/A

(45405009)

Acute sediment toxicity to freshwater 

invertebrates (amphipod, Hyalella azteca)

Supplemental

Non-guideline species; boscalid recoveries varied 

substantially based on analytical method; solvent 

controls sig. different from negative controls.

850.1735

(45405008)

Chronic toxicity to sediment-dwelling 

freshwater invertebrates (midge, Chironomus 

riparius)

Supplemental

Non-guideline species; sediment not spiked; 

measured concentrations not provided.

72-3

(45405004)

Acute toxicity to estuarine/marine fish 

(sheepshead minnow, Cyprinodon variegatus)

Acceptable

Ratio of highest concentration tested to EEC not 

high enough to evaluate risk to listed species.

72-3b

(45405002)

Acute toxicity to estuarine/marine 

invertebrates (mysid, Americanmysis bahia)

Acceptable

Ratio of highest concentration tested to EEC not 

high enough to evaluate risk to listed species.

123-2

(45405017)

Toxicity to nonvascular aquatic plants (green 

alga, Pseudokirchneriella subcapitata)

Supplemental

Study conditions poorly described.

71-2a

(45404923)

Subacute dietary toxicity to upland game 

birds (bobwhite quail, Colinus virginianus)

Supplemental

Poor rearing conditions; small sample size.

71-2b

(45404924)

Subacute dietary toxicity to waterfowl 

(mallard duck, Anas platyrhynchos L..

Supplemental

Poor rearing conditions; small sample size.

850.6200

(45405020)

14-day toxicity to soil-dwelling invertebrates 

(earthworm, Eisenia fetida)

Supplemental

Insufficient acclimation period; measured 

concentrations and stability unreported; 28-day 

study recommended.

850.4250

(47627402)

Terrestrial plant toxicity – Tier II vegetative 

vigor

Supplemental

Concentrations too high to establish definitive 

endpoints for cabbage (dicot).
-Page 45 of 52-

Appendix G. Environmental fate and transport data gaps and uncertainties

Guideline

(MRID)

Study Type Classification and

Issues

162-1 

835.4100

(45405208)

Aerobic soil metabolism Supplemental

Foreign soil, high moisture content, no replicates 

for degradates, combined data from 2 radiolabel 

studies to determine half-life of parent compound.

162-1

835.4100

(45405209)

Aerobic soil metabolism Supplemental

Info on degradate, 2-chloronicotinic acid only.

162-1

835.4100

(45405210)

Aerobic soil metabolism Unacceptable

Half-lives were extrapolated beyond range of data 

and no replicates. Interim report samples will be 

up to 360 days post treatment.

162-1

835.4100

(45643802)

Aerobic soil metabolism Acceptable

Replicate data not obtained for all sampling 

intervals to determine variability.

162-1

835.4100

(46715226)

Aerobic soil metabolism Supplemental

Not stated that samples incubated in darkness and 

material balance decreased steadily during study. 

Info on deg chloronicotinic acid and not parent.

162-2

835.4200

(45405211)

Anaerobic soil metabolism Unacceptable

Half-lives were extrapolated beyond range of data 

and no replicates. Incorrect application prep 

protocol. Foreign soil, not analyzed by phase but 

whole system. Study not required because 

acceptable anaerobic aquatic metabolism study has 

been submitted (MRID 45405213).

162-2

835.4200

(45405212)

Anaerobic soil metabolism Unacceptable

Half-lives were extrapolated beyond range of data 

and no replicates. Incorrect application prep 

protocol. Foreign soil, not analyzed by phase but 

whole system. Study not required because 

acceptable anaerobic aquatic metabolism study has 

been submitted (MRID 45405213).

162-4

835.4300

(45405214)

Aerobic aquatic metabolism Supplemental

System was flooded and incubated prior to 

treatment with parent. Should be done 

simultaneously. Foreign soil. Compound was 

stable and provides useful info. Additional study 

was not required at that time.

163-1

835.1230 &

835.1240

(45405216)

Leaching adsorption/desorption Supplemental

Material balances not reported for all test 

concentrations.

163-1

835.1230 &

835.1240

(45405217)

Leaching adsorption/desorption Supplemental

Material balances not reported for all test 

concentrations.
-Page 46 of 52-

Guideline

(MRID)

Study Type Classification and

Issues

164-1

835.6100

(45405218)

Soil field dissipation Supplemental

Major degradate from aerobic metabolism study 

not monitored.

164-1

835.6100

(45405221)

Soil field dissipation Acceptable

Note data variability at both sites makes reported 

DT50s of questionable value.

164-1

835.6100

(45405222)

Soil field dissipation Supplemental

Foreign study site. Half-lives at all 3 sites are 

questionable due to temporal and inter-replicate 

data variability at all sites and insufficient 

sampling intervals.
-Page 47 of 52-

Appendix H. LOCATES output of listed species

THREATENED AND ENDANGERED SPECIES LISTING BY STATE WITH USE CRITERIA

All medium types; minimum of 1 Acre.

Crops: Canola, rapeseed, crambe.

Taxa (dispersed species included): Mammal, marine mammal, bird, amphibian, reptile,

crustacean, gastropod, arachnid, insect, dicot, monocot, ferns, conifer, coral, lichen.

Alabama ( 5) species: Taxa

Woodpecker, Red-cockaded Endangered Bird No

Critical Habitat

(Picoides borealis) Terrestrial

Bladderpod, Lyrate Threatened Dicot No

(Lesquerella lyrata) Terrestrial

Clover, Leafy Prairie Endangered Dicot No

(Dalea foliosa) Terrestrial

Bat, Gray Endangered Mammal No

(Myotis grisescens) Subterraneous, Terrestrial

Bat, Indiana Endangered Mammal Yes

(Myotis sodalis) Subterraneous, Terrestrial

Arkansas ( 1) species: Taxa

Tern, Interior (population) Least Endangered Bird No

Critical Habitat

(Sterna antillarum) Terrestrial

California ( 25) species: Taxa

Salamander, California Tiger Endangered Amphibian No

Critical Habitat

(Ambystoma californiense) Terrestrial, Vernal pool

Toad, Arroyo Southwestern Endangered Amphibian Yes

(Bufo californicus (=microscaphus)) Freshwater, Terrestrial

Rail, Yuma Clapper Endangered Bird No

(Rallus longirostris yumanensis) Terrestrial

Fairy Shrimp, Vernal Pool Threatened Crustacean Yes

(Branchinecta lynchi) Vernal pool

Tadpole Shrimp, Vernal Pool Endangered Crustacean Yes

(Lepidurus packardi) Vernal pool

Adobe Sunburst, San Joaquin Threatened Dicot No

(Pseudobahia peirsonii) Terrestrial

Bird's-beak, Palmate-bracted Endangered Dicot No

(Cordylanthus palmatus) Terrestrial

Checker-mallow, Keck's Endangered Dicot Yes

(Sidalcea keckii) Terrestrial

Clover, Fleshy Owl's Threatened Dicot Yes

(Castilleja campestris ssp. succulenta) Vernal pool

Dudleya, Santa Clara Valley Endangered Dicot No

(Dudleya setchellii) Terrestrial

Golden Sunburst, Hartweg's Endangered Dicot No

(Pseudobahia bahiifolia) Terrestrial

Grass, Hairy Orcutt Endangered Dicot Yes

(Orcuttia pilosa) Vernal pool

Jewelflower, California Endangered Dicot No

(Caulanthus californicus) Terrestrial

Milk-vetch, Pierson's Threatened Dicot Yes
-Page 48 of 52-

(Astragalus magdalenae var. peirsonii) Terrestrial

California ( 25) species: Taxa

Pussypaws, Mariposa Threatened Dicot No

Critical Habitat

(Calyptridium pulchellum) Terrestrial

Woolly-threads, San Joaquin Endangered Dicot No

(Monolopia (=Lembertia) congdonii) Terrestrial

Beetle, Valley Elderberry Longhorn Threatened Insect Yes

(Desmocerus californicus dimorphus) Terrestrial

Fox, San Joaquin Kit Endangered Mammal No

(Vulpes macrotis mutica) Terrestrial

Kangaroo Rat, Fresno Endangered Mammal Yes

(Dipodomys nitratoides exilis) Terrestrial

Kangaroo Rat, Giant Endangered Mammal No

(Dipodomys ingens) Terrestrial

Sheep, Peninsular Bighorn Endangered Mammal Yes

(Ovis canadensis) Terrestrial

Grass, San Joaquin Valley Orcutt Threatened Monocot Yes

(Orcuttia inaequalis) Vernal pool

Lizard, Blunt-nosed Leopard Endangered Reptile No

(Gambelia silus) Terrestrial

Snake, Giant Garter Threatened Reptile No

(Thamnophis gigas) Freshwater, Terrestrial

Tortoise, Desert Threatened Reptile Yes

(Gopherus agassizii) Terrestrial

Colorado ( 6) species: Taxa

Crane, Whooping Endangered Bird Yes

Critical Habitat

(Grus americana) Terrestrial, Freshwater

Owl, Mexican Spotted Threatened Bird Yes

(Strix occidentalis lucida) Terrestrial

Butterfly Plant, Colorado Threatened Dicot Yes

(Gaura neomexicana var. coloradensis) Terrestrial

Ferret, Black-footed Endangered Mammal No

(Mustela nigripes) Terrestrial

Mouse, Preble's Meadow Jumping Threatened Mammal Yes

(Zapus hudsonius preblei) Terrestrial

Ladies'-tresses, Ute Threatened Monocot No

(Spiranthes diluvialis) Terrestrial

Georgia ( 10) species: Taxa

Salamander, Flatwoods Threatened Amphibian No

Critical Habitat

(Ambystoma cingulatum) Freshwater, Vernal pool, Terrestrial

Salamander, Reticulated flatwoods Endangered Amphibian No

(Ambystoma bishopi) Terrestrial

Stork, Wood Endangered Bird No

(Mycteria americana) Terrestrial

Woodpecker, Red-cockaded Endangered Bird No

(Picoides borealis) Terrestrial

Amphianthus, Little Threatened Dicot No

(Amphianthus pusillus) Freshwater

Dropwort, Canby's Endangered Dicot No

(Oxypolis canbyi) Terrestrial, Freshwater

Pondberry Endangered Dicot No

(Lindera melissifolia) Terrestrial
-Page 49 of 52-

Georgia ( 10) species: Taxa

Quillwort, Black-spored Endangered Ferns No

Critical Habitat

(Isoetes melanospora) Vernal pool

Bat, Indiana Endangered Mammal Yes

(Myotis sodalis) Subterraneous, Terrestrial

Snake, Eastern Indigo Threatened Reptile No

(Drymarchon corais couperi) Terrestrial

Idaho ( 8) species: Taxa

Crane, Whooping Endangered Bird Yes

Critical Habitat

(Grus americana) Terrestrial, Freshwater

Catchfly, Spalding's Threatened Dicot No

(Silene spaldingii) Terrestrial

Four-o'clock, Macfarlane's Threatened Dicot No

(Mirabilis macfarlanei) Terrestrial

Howellia, Water Threatened Dicot No

(Howellia aquatilis) Freshwater

Snail, Bliss Rapids Threatened Gastropod No

(Taylorconcha serpenticola) Freshwater

Snail, Snake River Physa Endangered Gastropod No

(Physa natricina) Terrestrial

Bear, Grizzly Threatened Mammal No

(Ursus arctos horribilis) Terrestrial

Caribou, Woodland Endangered Mammal No

(Rangifer tarandus caribou) Terrestrial

Illinois ( 1) species: Taxa

Bat, Indiana Endangered Mammal Yes

Critical Habitat

(Myotis sodalis) Subterraneous, Terrestrial

Indiana ( 1) species: Taxa

Bat, Indiana Endangered Mammal Yes

Critical Habitat

(Myotis sodalis) Subterraneous, Terrestrial

Kansas ( 5) species: Taxa

Crane, Whooping Endangered Bird Yes

Critical Habitat

(Grus americana) Terrestrial, Freshwater

Plover, Piping Endangered Bird Yes

(Charadrius melodus) Terrestrial

Tern, Interior (population) Least Endangered Bird No

(Sterna antillarum) Terrestrial

Beetle, American Burying Endangered Insect No

(Nicrophorus americanus) Terrestrial

Orchid, Western Prairie Fringed Threatened Monocot No

(Platanthera praeclara) Terrestrial

Kentucky ( 3) species: Taxa

Warbler, Bachman's Endangered Bird No

Critical Habitat

(Vermivora bachmanii) Terrestrial

Bat, Gray Endangered Mammal No

(Myotis grisescens) Subterraneous, Terrestrial

Bat, Indiana Endangered Mammal Yes

(Myotis sodalis) Subterraneous, Terrestrial

 Maine ( 3) species: Taxa

Lousewort, Furbish Endangered Dicot No

Critical Habitat
-Page 50 of 52-

(Pedicularis furbishiae) Terrestrial

Lynx, Canada Threatened Mammal No

(Lynx canadensis) Terrestrial

Orchid, Eastern Prairie Fringed Threatened Monocot No

(Platanthera leucophaea) Terrestrial

Michigan ( 11) species: Taxa

Plover, Piping Endangered Bird Yes

Critical Habitat

(Charadrius melodus) Terrestrial

Warbler (=Wood), Kirtland's Endangered Bird No

(Dendroica kirtlandii) Terrestrial

Goldenrod, Houghton's Threatened Dicot No

(Solidago houghtonii) Terrestrial

Monkey-flower, Michigan Endangered Dicot No

(Mimulus glabratus var. michiganensis) Terrestrial, Freshwater

Thistle, Pitcher's Threatened Dicot No

(Cirsium pitcheri) Terrestrial

Butterfly, Karner Blue Endangered Insect No

(Lycaeides melissa samuelis) Terrestrial

Butterfly, Mitchell's Satyr Endangered Insect No

(Neonympha mitchellii mitchellii) Terrestrial

Bat, Indiana Endangered Mammal Yes

(Myotis sodalis) Subterraneous, Terrestrial

Lynx, Canada Threatened Mammal No

(Lynx canadensis) Terrestrial

Iris, Dwarf Lake Threatened Monocot No

(Iris lacustris) Terrestrial

Orchid, Eastern Prairie Fringed Threatened Monocot No

(Platanthera leucophaea) Terrestrial

Minnesota ( 3) species: Taxa

Plover, Piping Endangered Bird Yes

Critical Habitat

(Charadrius melodus) Terrestrial

Lynx, Canada Threatened Mammal No

(Lynx canadensis) Terrestrial

Orchid, Western Prairie Fringed Threatened Monocot No

(Platanthera praeclara) Terrestrial

Montana ( 6) species: Taxa

Crane, Whooping Endangered Bird Yes

Critical Habitat

(Grus americana) Terrestrial, Freshwater

Plover, Piping Endangered Bird Yes

(Charadrius melodus) Terrestrial

Tern, Interior (population) Least Endangered Bird No

(Sterna antillarum) Terrestrial

Catchfly, Spalding's Threatened Dicot No

(Silene spaldingii) Terrestrial

Bear, Grizzly Threatened Mammal No

(Ursus arctos horribilis) Terrestrial

Ferret, Black-footed Endangered Mammal No

(Mustela nigripes) Terrestrial
-Page 51 of 52-

North Carolina ( 2) species: Taxa

Woodpecker, Red-cockaded Endangered Bird No

Critical Habitat

(Picoides borealis) Terrestrial

Manatee, West Indian Endangered Marine mml Yes

(Trichechus manatus) Saltwater

North Dakota ( 4) species: Taxa

Crane, Whooping Endangered Bird Yes

Critical Habitat

(Grus americana) Terrestrial, Freshwater

Plover, Piping Endangered Bird Yes

(Charadrius melodus) Terrestrial

Tern, Interior (population) Least Endangered Bird No

(Sterna antillarum) Terrestrial

Orchid, Western Prairie Fringed Threatened Monocot No

(Platanthera praeclara) Terrestrial

Ohio ( 2) species: Taxa

Bat, Indiana Endangered Mammal Yes

Critical Habitat

(Myotis sodalis) Subterraneous, Terrestrial

Orchid, Eastern Prairie Fringed Threatened Monocot No

(Platanthera leucophaea) Terrestrial

Oregon ( 12) species: Taxa

Murrelet, Marbled Threatened Bird Yes

Critical Habitat

(Brachyramphus marmoratus marmoratus) Freshwater, Terrestrial, Saltwater

Owl, Northern Spotted Threatened Bird Yes

(Strix occidentalis caurina) Terrestrial

Plover, Western Snowy Threatened Bird Yes

(Charadrius alexandrinus nivosus) Terrestrial

Catchfly, Spalding's Threatened Dicot No

(Silene spaldingii) Terrestrial

Checker-mallow, Nelson's Threatened Dicot No

(Sidalcea nelsoniana) Terrestrial

Daisy, Willamette Endangered Dicot No

(Erigeron decumbens var. decumbens) Terrestrial

Four-o'clock, Macfarlane's Threatened Dicot No

(Mirabilis macfarlanei) Terrestrial

Lomatium, Bradshaw's Endangered Dicot No

(Lomatium bradshawii) Terrestrial, Freshwater

Lupine, Kincaid's Threatened Dicot No

(Lupinus sulphureus (=oreganus) ssp. kincaidii (=var. kincaidii)) Terrestrial

Thelypody, Howell's Spectacular Threatened Dicot No

(Thelypodium howellii spectabilis) Terrestrial

Butterfly, Fender's Blue Endangered Insect No

(Icaricia icarioides fenderi) Terrestrial

Butterfly, Oregon Silverspot Threatened Insect Yes

(Speyeria zerene hippolyta) Terrestrial

Pennsylvania ( 1) species: Taxa

Bat, Indiana Endangered Mammal Yes

Critical Habitat

(Myotis sodalis) Subterraneous, Terrestrial
-Page 52 of 52-

South Dakota ( 5) species: Taxa

Crane, Whooping Endangered Bird Yes

Critical Habitat

(Grus americana) Terrestrial, Freshwater

Plover, Piping Endangered Bird Yes

(Charadrius melodus) Terrestrial

Tern, Interior (population) Least Endangered Bird No

(Sterna antillarum) Terrestrial

Beetle, American Burying Endangered Insect No

(Nicrophorus americanus) Terrestrial

Ferret, Black-footed Endangered Mammal No

(Mustela nigripes) Terrestrial

Utah ( 1) species: Taxa

Primrose, Maguire Threatened Dicot No

Critical Habitat

(Primula maguirei) Terrestrial

Washington ( 4) species: Taxa

Owl, Northern Spotted Threatened Bird Yes

Critical Habitat

(Strix occidentalis caurina) Terrestrial

Catchfly, Spalding's Threatened Dicot No

(Silene spaldingii) Terrestrial

Howellia, Water Threatened Dicot No

(Howellia aquatilis) Freshwater

Rabbit, Pygmy Endangered Mammal No

(Brachylagus idahoensis) Terrestrial

Wisconsin ( 4) species: Taxa

Locoweed, Fassett's Threatened Dicot No

Critical Habitat

(Oxytropis campestris var. chartacea) Terrestrial

Thistle, Pitcher's Threatened Dicot No

(Cirsium pitcheri) Terrestrial

Lynx, Canada Threatened Mammal No

(Lynx canadensis) Terrestrial

Orchid, Eastern Prairie Fringed Threatened Monocot No

(Platanthera leucophaea) Terrestrial

11/18/2010 9:05:29 AM Ver. 2.10.4