Office of Pmntion, Pesticides, 

and Toxic Substances 

Environmental Fate and Ecological Risk Assessment for the 

Registration of Florasulam 

Florasulam 

CAS No. 145701-23-1 PC Code 129108 

TEXT SEARCHABLE DOCUMENT
I. Executive Summary 

A. Nature of the Chemical Stressor 

B. Conclusions - Exposure Characterization 

C. Conclusions - Effects Characterization 

D. Potential Risks to Non-target Organisms 

E. Data Gaps and Uncertainties 

11. Problem Formulation 

A. Previous Assessments 

B. Stressor Source and Distribution 

1. Source and Intensity 

2. Physical/Chemical/Fate and Transport Properties 

3. Pesticide Type, Class, and Mode of Action 

4. Usage Overview 

B. Receptors 

C. Assessment Endpoints 

D. Conceptual Model 

1. Diagram 

2. Risk Hypothesis 

E. Analysis Plan 

11. Analysis 

A. Use Characterization 

B. Exposure Characterization 

1. Environmental Fate and Transport Characterization 

2. Aquatic Exposure 

3. Terrestrial Exposure 

C. Ecological Effects Characterization 

1. Aquatic Effects 

2. Terrestrial Effects 

3. ECOTOX 

111. Risk Characterization 

A. Risk Estimation 

1. Aquatic Species 

2. Terrestrial 

B. Risk Description 

1. Aquatic 

2. Terrestrial 

C. Uncertainties and Data Gaps 

IV. Conclusion 

V. Threatened and Endangered Species 

A. Action Area 

B. Taxonomic Groups Potentially at Risk 

C. Indirect Effects Analysis 

D. Critical Habitat 

E. Co-occurrence Analysis 

VI. References 
I, EXECUTIVE SUMMARY 

A. Nature of the Chemical Stressor 

The Environmental Fate and Effects Division (EFED) has reviewed the proposed use of 

florasulam as an herbicide for the postemergent control of broadleaf weeds in wheat, barley, rye and 

triticale crops. Florasulam, a sulfonamide ALS inhibitor, is proposed for Section 3 registration in 

the United States (U.S.) as an active ingredient in four formulated products. The proposed labels 

allow application as an aerial or ground spray at a maximum rate of 0.0045 lb ai/A. Florasulam was 

registered in Canada in 2001 and this assessment draws considerable support from Health Canada's 

Pesticide Management Regulatory Agency (PMRA) Product Monograph and data evaluation 

records. However, all fate and toxicity studies were reviewed and classified by EPA scientists for 

this assessment. 

B. Conclusions - Exposure Characterization 

Florasulam (XDE-570) is a very mobile compound that is not persistent in aerobic soil, 

rapidly degrading to the major degradate 5-OH-XDE-570, which is in turn more slowly biodegraded 

to other degradates and eventually to C02 and bound residues. Florasulam is not significantly 

degraded by abiotic processes. It readily degrades in aquatic systems, where it is biotransformed to 

5-OH-XDE-570, which is then slowly further biotransformed in some aerobic systems, but stable in 

other aerobic systems and in anaerobic systems. The degradate 5-OH-XDE-570 is more mobile in 

soil than the parent compound. Persistence or accumulation of the parent compound is not expected 

in the field based on laboratory soil studies and terrestrial field dissipation studies. The persistence 

and accumulation of 5-OH-XDE-570 is more variable than that of the parent, indicating it may 

persist at some sites, but not others. Submitted data indicate that the parent compound has a very 

low potential to bioaccumulate in aquatic organisms. 

There is a potential for florasularn to reach surface water through spray drift and for both the 

parent compound and 5-OH-XDE-570 to reach surface water through runoff or subsurface flow, 

although this will be somewhat decreased for the parent due to its rapid biodegradation in aerobic 

soil. For 5-OH-XDE-570, the potential to reach surface water through runoff is greater than for the 

parent due to its slower biotransformation in aerobic soil and higher water solubility. For both 

compounds, the potential to reach surface water through runoff will be reduced by any leaching that 

occurs in the field. 

Based on the results of laboratory and field studies, in which leaching was observed, both 

florasulam and 5-OH-XDE-570 have the potential to leach to groundwater. However, for the 

parent, the potential to leach downward and to reach groundwater will be somewhat reduced by the 

fairly rapid biotransformation of the parent in aerobic soil. For 5-OH-XDE-570, the potential to 

leach is greater than that of the parent due to its slower biotransformation in aerobic soil and higher 

water solubility. For either compound, both of which partition mainly to the water phase, the 

potential to leach will be greater when there is excessive rainfall or irrigation, particularly if either 

of these occur close to the time of application. These concerns have also been identified in the 

Canadian and EU risk assessments for florasulam. 

C. Conclusions - Effects Characterization 

Based on the data submitted in support of registration, florasularn is considered practically 

3 of 44 
nontoxic on an acute exposure basis to aquatic and terrestrial wildlife. There was 40%, 60% and 

100% mortality at the three highest (810, 1350 and 2250 mg aikg) treatment levels in the avian 

acute oral study. There were no mortalities at the 175,292 or 486 mgkg treatment levels, but 

sublethal effects were noted at all but the lowest dose tested. No effects were observed in the avian 

subacute dietary or avian reproduction studies. No effects were reported in the acute rat study. 

Sublethal effects on weight gain were observed in the two-generation rat reproduction study at the 

highest treatment level. Some mortality (<20%) was observed in the contact and oral bee studies at 

100 pglbee. No adverse effects attributable to florasulam were observed in acute and chronic 

studies with fish and aquatic invertebrates. As expected with an herbicide, effects were observed in 

both aquatic and terrestrial plant studies. 

The major degradate, 5-OH-XDE-570, is classified as practically nontoxic to aquatic 

invertebrates and fish based on submitted studies. 5-OH-XDE-570 is considered not toxic to 

earthworms up to 1120 mg ai/kg soil, and is less toxic to aquatic nonvascular plants (by several 

orders of magnitude) than the parent florasulam. The toxicity of 5-OH-XDE-570 to aquatic vascular 

and terrestrial plants is uncertain. A 48-hr study of the toxicity of other degradates revealed no 

adverse effects to daphnids. 

D. Potential Risks to Non-target Organisms 

Based on this screening-level assessment, the use of florasulam according to label direction 

should not result in direct acute or chronic effects to aquatic or terrestrial wildlife. Based on the 

submitted guideline studies, the RQs for direct effects to aquatic vascular and nonvascular plants are 

also below the level of concern (LOC). Adverse effects on sensitive terrestrial plant species cannot 

be precluded at distances of greater than 900 feet from the edge of field. Indirect effects to 

terrestrial or aquatic wildlife cannot be ruled out due to the potential for florasulam to effect changes 

in plant populations which may lead to changes in food supply or habitat. Table 1 summarizes the 

listed taxa potentially at risk from direct andlor indirect effects due to the use of florasulam on 

cereal grains. 
Table 1. Listed species risks associated with potential direct or indirect effects from the proposed 

use of florasulam on cereal grains. 

Listed Taxon 

Terrestrial and semi-aquatic Yes plants - dicots I 

Terrestrial and semi-aquatic 

plants - monocots 

Direct Effects 

Acute 

Yes 

Insects 

Birds 

Direct Effects 

Chronic 

yes' 

Terrestrial-phase amphibians I No 

Indirect Effects 

No 

NO 

Reptiles 

Mammals 

Aquatic plants 

No 

Freshwater fish 

Aquatic-phase amphibians 

Freshwater invertebrates 

E. Data Gaps and Uncertainties 

No 

yes' 

No 

No 

No 

Mollusks 

Marinelestuarine fish 

Marinelestuarine crustaceans 

The environmental fate database is nearly complete and constitutes a strong point in this 

assessment, as both the degradation (type and rate) and mobility of the pesticide have been well 

established. Acceptable studies have been submitted for hydrolysis, photolysis (aqueous and on 

soil), aquatic metabolism (anaerobic and aerobic), mobility in soil, and terrestrial field dissipation 

(one site). Although multiple aerobic soil metabolism studies were submitted, each was classified 

"supplemental" (with the exception of one classified "not acceptable"). The single aerobic soil 

metabolism study conducted with U.S. soils was classified "not acceptable"; none of the 

supplemental studies were conducted with U.S. soils. Because the parent degrades fairly rapidly, 

additional data for use in determining the half-life of the parent would not substantially decrease the 

5 of 44 

yes' 

yes1 

No 

NO 

No 

No 

No 

 onli listed LOC is exceeded for terrestrial plants, therefore there is potential for adverse effects to those species that rely 

either on a specific plant species or multiple plant species. Indirect effects may include general habitat modification, 

host plant loss, and food supply disruption. 

No 

No 

No 

- 

yes' 

yes' 

yes' 

No 

No 

No 

yes1 

yes' 

yes' 

No 

No 

No 

yes1 

yes1 

yes' 
uncertainty associated with the exposure assessment. However, additional aerobic soil metabolism 

data would add to the available information on the degradates, as the submitted studies were 

incomplete in that respect. 

Terrestrial field dissipation data were submitted from only one U.S. site. Although data for 

multiple foreign field sites were submitted, those studies were classified "supplemental" partially 

because the depth of sampling was insufficient to show the extent of leaching that may occur in the 

field for both the parent and 5-OH-XDE-570. For cereal grains use, which covers a wide 

geographic area, data from additional U.S. sites would decrease the uncertainty inherent in using 

data from a single location to determine terrestrial dissipation rates. 

The ecological effects database is largely complete and the effects on guideline taxa of 

exposure to the active ingredient the pesticide have been established. Additional data regarding 

degradates and formulation toxicity have been submitted and reviewed. 

The seedling emergence study was highly variable in some test species which likely 

contributed to a lack of statistical power. While there was no statistically significant effect greater 

than 25% on the emergence, shoot length or biomass of any of the species tested in the seedling 

emergence study, several species (carrot, onion, soybean, cucumber, tomato) exhibited inhibitions 

ranging from 5% to 26% at rates as low as 0.00001 lbs ai/A. For example, at 0.00001 lbs ai/A (the 

lowest dose tested), tomatoes exhibited a mean 26% reduction in biomass relative to the control, but 

at 0.0029 lbs ai/A, a mean 5% increase in biomass relative to the control was observed. The 

replicate coefficients of variance (CV) for the treatments ranged from 12.4% to 80.5%, while the 

control CV was 3.4%. The variability in this study is a source of uncertainty in this assessment, but 

is not thought to appreciably affect the risk conclusions. 

This assessment assumes one growing season per year, based on common agricultural 

practices. However, the number of growing seasons per year is not limited by the label; areas with 

multiple growing seasons could result in greater exposures on an annual basis. 

Given that the parent is short-lived, the application rate is low, only one application is 

needed per season, and that the label has crop rotation restrictions, there may be herbicidal activity 

for longer than is suggested by fate properties of the parent alone. The toxicity of the degradates to 

vascular plants is uncertain. 

11. PROBLEM FORMULATION 

A. Previous Assessments 

Florasulam has not previously been assessed for use in the United States by OPP. Although 

both fate and toxicity studies were reviewed and classified by EPA scientists, EPA, under a 

workshare agreement with Health Canada's Pesticide Management Regulatory Agency (PMRA), 

draws support from a previous environmental risk assessment by PMRA conducted in support of the 

registration of florasulam in Canada (Product Monograph, June, 2001). Overall risk conclusions are 

the same; any differences between the two risk assessments are based primarily on differing 

methods for estimating exposure and risk. 
B. Stressor Source and Distribution 

1. Source and Intensity 

This document evaluates the environmental fate and the potential ecological risk fkom the 

proposed use of florasulam for the postemergent control of broadleaf weeds in wheat, barley, oat, 

rye and triticale crops. Application methods include both aerial and ground spray, at a maximum 

rate of 0.0045 lb ai/A. Because this would be the first time florasularn is registered for use in the 

U.S., the potential extent of use is not known. However, given the widespread distribution of areas 

that grow cereal grains, a nationwide use is assumed. 

2. PhysicaUChernicaUFate and Transport Properties 

Florasulam (XDE-570) is a very mobile compound (all measured Kds are <I) that is not 

persistent in aerobic soil, with laboratory half-lives of 0.7-8.3 days. It is stable to hydrolysis except 

at alkaline pHs, where it hydrolyzes slowly (half-life of 99 days). Florasulam photodegrades slowly 

in water (half-life of 46 days), but is stable to photodegradation on soil. In aquatic environments, 

florasulam degrades readily (half-lives of 3-1 8 days in aerobic systems and 2-1 3 days in anaerobic 

systems). In aquatic systems, florasulam is biotransformed to the major degradate 5-OH-XDE-570, 

which is then slowly biotransformed in some aerobic systems (half-life of 169 days), but stable in 

other aerobic systems and in anaerobic systems. Thus, the degradate is expected to be persistent in 

most aquatic systems. The 5-OH-XDE-570 degradate is also more persistent than florasulam in 

aerobic soil (half-lives of 10-56 days), and is more mobile in soil than the parent compound. 

Persistence and accumulation of the parent compound are not expected in the field based on 

laboratory soil studies and terrestrial field dissipation studies. The persistence and accumulation of 

5-OH-XDE-570 is more variable than that of the parent, indicating that the compound may persist at 

some sites, but not others. Submitted data indicate that the parent compound has a very low 

potential to bioaccumulate in aquatic organisms. 

There is a potential for florasulam to reach surface water through spray drift, as the 

compound may be applied by ground or aerial sprays. Because both the parent compound and 5- 

OH-XDE-570 are very mobile in soil, there is also the potential for them to reach surface water 

through runoff or lateral subsurface flow, although this potential will be somewhat decreased for the 

parent due to its rapid biodegradation in aerobic soil. For 5-OH-XDE-570, the potential to reach 

surface water through runoff is greater than for the parent due to its slower biotransformation in 

aerobic soil and much higher water solubility. For both the parent and the degradate, however, the 

potential to reach surface water through runoff will be reduced by any leaching that occurs in the 

field. 

Based on the results from the laboratory batch equilibrium studies and column leaching 

studies, and supported by the results of multiple terrestrial field dissipation studies in which 

leaching was observed, both florasulam and 5-OH-XDE-570 have the potential to leach to 

groundwater. However, for the parent compound, the potential to leach will be somewhat reduced 

by the fairly rapid biotransformation of the parent in aerobic soil. For 5-OH-XDE-570, the potential 

to leach is greater than for the parent due to its slower biotransformation in aerobic soil and much 

higher water solubility. For either compound, both of which partition mainly to the water phase, 

the potential to leach will be greater when there is excessive rainfall or irrigation, particularly if 

either of these occur close to the time of application. These concerns have also been identified in 
the Canadian and EU risk assessments for florasulam. 

3. Pesticide Type, Class, and Mode of Action 

a) Chemical Profile 

Common name: florasulam 

IUPAC: 2',6',8-trifluoro-5-methoxy[l,2,4]triazolo[l,5-c]pyrimidine-2-sulfonanilide 

CAS name: N-(2,6-difluorophenyl)-8-fluoro-5-methoxy[l,2,4] triazolo[ l,5-clpyrimidine2-sulfonarnide 

CAS NO.: 145701-23-1 

Chemical structure: 

b) Mode of Action 

Florasulam is a sulfonamide herbicide intended to control broadleaf weeds postemergence. 

Sulfonamides are one of several classes of chemicals (with sulfonylureas and imidazolinones) that 

kill plants through the inhibition of acetolactate synthase (ALS), an enzyme critical to the 

biosynthesis of branch-chain amino acids (valine, leucine, and isoleucine). These chemicals 

primarily affect plants or meristematic tissues that are in an active growth stage. Older plants have 

been known to exhibit varied signs of malformation, stunting, and reduced fruitheed production 

when exposed to ALS inhibitors. Weeds can become resistant to individual ALS inhibitors, 

presumably because these herbicides have a single mode of action and because many have long 

residual activity. Generally, grasses (Poaceae) tend to be more resistant to ALS inhibitors as they 

more rapidly metabolize the chemical to nontoxic metabolites than most other plant species. 

4. Usage Overview 

Florasulam is not currently registered for use in the United States; however, the herbicide 

has been registered for use on cereal grains in Canada. The pesticide is proposed for use on wheat, 

barley, oat, rye and triticale crops for postemergent control of broadleaf weeds. 
B. Receptors 

Ecological effect endpoints are derived from registrant-submitted guideline studies as 

required for registration under the Federal Insecticide, Fungicide and Rodenticide Act (FIFRA; 40 

CFR Part 158), as well as a review of data available through acceptable open literature (ECOTOX; 

www.epa.gov/ecotox), when available. The most sensitive endpoints (described below) from 

testing of surrogate species are used to estimate risk to the taxonomic group(s) represented by the 

surrogate tested. Toxicity testing reported in this document is intended to represent all terrestrial 

and aquatic organisms. However, only a few surrogate species are used to represent all freshwater 

fish (2000+), bird (680+) and plant (1 9,000+) species in the United States. In addition, neither 

reptiles nor amphibians are routinely tested. Bird data are used as surrogates for reptiles and 

terrestrial-phase amphibians; fish data are used as surrogates for aquatic-phase amphibians. The 

Norway rat is typically the surrogate for all mammals. 

C. Assessment Endpoints 

Assessment endpoints are defined, per Agency guidelines, as "explicit expressions of the 

actual environmental value that is to be protected" which are "operationally defined by an ecological 

entity and its attributes" (USEPA, 2004). The ecological entity can be a species, a functional group 

of species, a community, an ecosystem, or another entity of importance or concern. An attribute is 

the characteristic of the entity that is important to protect and is potentially at risk. 

Defining an assessment endpoint involves two steps: 1) identifllng the valued attributes of the 

environment that are considered to be at risk, and 2) operationally defining the assessment endpoint 

in terms of an ecological entity (e.g., a community of fish and aquatic invertebrates) and its 

attributes (i.e., growth, survival and reproduction). Therefore, selection of the assessment endpoints 

is based on valued entities (i.e., ecological receptors), the ecosystems potentially at risk and the 

routes by which ecological receptors are exposed to the pesticide. The selection of clearly defined 

assessment endpoints is important because they provide direction and boundaries in the risk 

assessment for addressing risk management issues of concern. 

Typical assessment endpoints for screening-level pesticide ecological risk assessments include 

reduced survival and/or reproductive impairment for both aquatic and terrestrial animal species from 

direct acute or direct chronic exposures. Aquatic animal groups that are typically characterized in 

the risk assessment include: freshwater and estuarine/marine fish and invertebrates. Terrestrial 

animal groups include birds, mammals, and, qualitatively, beneficial insects. All assessment 

endpoints are characterized at the individual level in order to protect threatened and endangered 

species. However, risks to higher biological levels (i.e., populations and communities) can be 

inferred from this approach (e.g., pesticide effects on individual survival and fecundity may impact 

population stability, growth, and/or habitat carrying capacity). A species-specific assessment 

containing characterization of indirect effects to listed species and critical habitat is the next step 

following completion of the screening-level risk assessment. 

For terrestrial and semi-aquatic plants, the baseline assessment endpoint is the perpetuation of 

populations of non-target species (crops and non-crop plant species). Existing test requirements 

only evaluate the seedling emergence and vegetative vigor of annuals. Although it is recognized 

that the endpoints of seedling emergence and vegetative vigor may not address all terrestrial and 

semi-aquatic plant life cycle components, it is assumed that impacts on plant emergence and/or on 
active growth have the potential to impact individual competitive ability and reproductive success, 

from which population effects can be inferred. 

For aquatic plants, the assessment endpoint is the maintenance and growth of standing crop or 

biomass. Measurement endpoints for this assessment focus on nonvascular, e.g., algae, and vascular 

plants, e.g., duckweed (Lemna gibba), growth rates and biomass measurements. 

The ecological relevance of the assessment endpoints assumes that complete exposure 

pathways exist for these receptors, that the receptors may be sensitive to pesticides in affected media 

and/or forage items and that the receptors could potentially inhabit areas where pesticides are 

applied, or areas where runoff andlor spray drift may impact the sites because suitable habitat is 

available. 

Ecological measurement endpoints for this screening-level risk assessment are based on a 

suite of registrant-submitted toxicity studies performed on a limited number of organisms, 

supplemented by the open literature where applicable, in the following broad groupings: 

1. Birds, e.g. Northern bobwhite quail (Colinus virginiana) and mallard duck (Anas 

platyrhynchos), also used as surrogate species for terrestrial-phase amphibians and 

reptiles, 

2. Mammals, e.g. laboratory rat (Rattus nowegicus), 

3. Freshwater fish, e.g. rainbow trout (Oncorhynchus mykiss), also used as a surrogate 

for aquatic-phase amphibians, 

4. Freshwater invertebrates, e.g. waterflea (Daphnia magna), 

5. Estuarinelmarine fish, e.g. silverside (Menidia beryllina) 

6. Estuarinelmarine invertebrates, e.g. Eastern oyster (Crassostrea virginica) 

7. Terrestrial plants, 

8. Algae and aquatic plants. 

Within each of these broad taxonomic groups, an acute and chronic endpoint is selected 

from the available test data. The selection is made from the most sensitive species tested within a 

particular surrogate group. If additional toxicity data are available from other sources, the selection 

of an endpoint may not be limited to the surrogate species listed above, but may be expanded to 

include those data for other groups or species that have been deemed of sufficient quality by the 

Agency for use in the risk assessment. 

D. Conceptual Model 

In order for a chemical to pose an ecological risk, it must reach ecological receptors in 

biologically significant concentrations. Exposure pathways are defined as the means by which a 

contaminant moves in the environment from a source to an ecological receptor. For an ecological 

exposure pathway to be complete, it must have a source, an environmental transport medium, a 

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

Because florasulam's mode of action is the inhibition of branch-chain amino acid synthesis, 

a metabolic pathway not present in animals, florasulam is not expected to result in direct risk to 

terrestrial or aquatic fauna. However, florasulam applied in accordance with the proposed label may 

result in sufficient exposure to nontarget aquatic and terrestrial plants to result in adverse effects 

10 of 44 
(e.g. reduction in growth or survival). Additionally, nontarget species may be indirectly affected by 

florasulam usage due to a loss of food resources and/or changes to ecologically critical habitat 

resulting fi-om labeled uses. 

1. Diagram 

The conceptual model used to depict the potential ecological risk associated with the use of 

florasulam (the stressor) assumes that as a pesticide, florasulam can adversely affect terrestrial and 

aquatic organisms (the receptors) if environmental concentrations exceed toxic thresholds as a result 

of application according to the label directions (Figure 1). Ecological receptors that may potentially 

be exposed to florasulam include terrestrial and semi-aquatic wildlife (e.g., mammals, birds, 

amphibians and reptiles), terrestrial and semi-aquatic plants, terrestrial invertebrates (e.g., honey 

bees), and terrestrial soil and aquatic sediment invertebrates. Additionally, given the mobility of 

florasulam and its primary degradate, aquatic organisms (i.e., ffeshwater and estuarine/marine fish 

and invertebrates, amphibians, and aquatic plants) are potential receptors in adjacent water bodies 

through off-site transport of florasulam from the application site through runoff, erosion and/or 

spray drift. 

Routes of exposure to terrestrial and aquatic organisms can occur fi-om direct application, 

spray drift and/or runoff. Exposure may be through ingestion of contaminated food or water 

sources, dermal contact or absorption, and/or inhalation. 

This assessment does not take into account potential atmospheric transport in estimating 

environmental concentrations or potential exposure via groundwater, nor does it account for 

ingestion of florasulam residues by animals in contaminated grit, ingestion through preening 

activities, or uptake through inhalation or dermal absorption by terrestrial animals. Exposure to 

terrestrial animals is based primarily on dietary consumption of foliar (and insect) residues. Aquatic 

assessments assume that all potential routes of direct exposure are accounted for. 
Stressor Florasulam Applied as Aerial or Ground Spray to Target Crops 

Sourcel 

Transport 

Pathways 

Sourcel 

Exposure 

Media 

Exposure 

Route 

Receptors 

Attribute 

Changes 

I 

Terrestrial Food FoliageiRootslSeeds 

(foliage, 

fruits, insects) 

Terrestrial Phase Amphibians 

Individual Animals 

Reduced survival 

Reduced growth 

Reduced reproduction 

Reduced survival, 

dividual Vertebrates 

and Invertebrates 

Reduced survival 

Reduced growth L Reduced reproduction 

Reduced growth 

Bold lines indicate pathways of primary concern in this risk assessment 

Figure 1. Conceptual Model for a Screening Level Assessment of Florasularn. Dashed lines 

indicate exposure routes not evaluated; bold lines indicate routes of exposure hypothesized to be of 

greatest importance. 

2. Risk Hypothesis 

Based on the mode of action, use ofjlorasulam according to label directions is not expected 

to result in direct adverse effects to non-target animal species; however, its use as directed may 

cause adverse effects to nontarget plant species in the environment. Indirect effects on aquatic and 

terrestrial animal communities may occur due to decreased primary productivity. 

E. Analysis Plan 

The proposed label maximum application rates for the use of florasulam were selected for 

modeling environmental concentrations for this baseline, deterministic (risk-quotient based) 

assessment. The most sensitive toxicity endpoints from surrogate test species are used to estimate 

treatment-related effects on growth and survival assessment endpoints. Estimated environmental 

concentrations (EECs) used in terrestrial and aquatic ecological risk assessments are based on 

florasulam parent compound, as no toxic effects were reported in studies of the degradates. 

However, the toxicity of the primary degradate on terrestrial and aquatic vascular plants remains 

uncertain. 
A risk quotient-based approach is used in this assessment, comparing the ratio of exposure 

concentrations to effects endpoints with predetermined levels of concern (LOCs). The use, 

laboratory environmental fate and laboratory ecological effects data, all of which provide the basis 

for these risk quotients, are characterized in the assessment. Although risk is often defined as the 

likelihood and magnitude of adverse ecological effects, the risk quotient-based approach does not 

provide a quantitative estimate of likelihood and/or magnitude of an adverse effect. 

11. ANALYSIS 

A. Use Characterization 

Florasulam is an active ingredient in four formulated products proposed for the postemergent 

control of broadleaf weeds in wheat, barley, oat, rye and triticale crops. Florasulam is the sole 

active ingredient in formulated product EF-1343 (4.84%; proposed EPA reg. # 62719-LAN), and is 

also formulated in combination with other active ingredients. EF-1383 (62719-LLI) contains 0.58% 

florasulam with 42.33% 2,4-D, GF-184 (62719-LAG) contains 0.25% florasulam with 14.53% 

fluroxypyr and GF-1727 (62719-LAE) contains 0.39% florasulam and 42.25% MCPA. This 

ecological risk assessment considers the potential for risk from florasulam alone. The other active 

ingredients have their own risk assessments; the potential for additive or synergistic effects is not 

quantitatively considered in this document. 

The application rate for florasulam is essentially the same for all four products, but was 

calculated from the proposed label for EF-1343. All four products are labeled for one application of 

0.0045 Ibs ai/A per growing season. Application is limited by the label to one per growing season. 

While some areas may have more than one growing season per year, it would be an uncommon 

cultural practice to follow one of the target crops with another of the target crops in the same year. 

Application can be made by ground or aerial spray. Spray drift reduction practices are included on 

the labels. However, droplet size, an important factor in spray drift, is not limited, although larger 

droplet size is recommended. Chemigation is specifically prohibited by the labels. Warnings 

regarding potential hazard to non-target crop species and crop rotation intervals (0- 12 months, 

depending on crop) are included on the labels. An advisory regarding the potential for the products 

to leach to groundwater is also included on the proposed labels. Application information is 

presented in Table 2. 

Table 2. Summary use information for florasulam, based on EF-1343, GF-1727, EF-1383, and GF184 labels. 

The formulation of the products was not specifically stated on the proposed labels (each 

dated 311 3/06 with the exception of GF-184, dated 3/07/06), but is assumed to be a liquid 

13 of 44 

cereal 

grains 

cereal 

grains 

0.0045 

0.0045 

1 

1 

0.0045 

0.0045 

not 

applicable 

not 

applicable 

ground 

spray 

aerial 

spray 

0 (foliar) 

0 (foliar) 
formulation (possibly a soluble concentrate) for each of the four products. 

Because florasulam is a new chemical not previously registered in the U.S., the potential 

extent of use cannot be estimated. However, the widespread distribution of the target crops can 

serve as an index of potential use. According to the USDA National Agricultural Statistics Service 

(NASS, 2007), wheat is grown in 40 states, 1 1 of which cultivate over one million acres. The most 

acreage planted in wheat is in Kansas (9,100,000 acres) and South Dakota (8,290,000 acres). Barley 

is grown in 23 states, with the most acreage in North Dakota (1,100,000 acres) and Montana 

(770,000 acres). Triticale is planted in 27 states, the most acreage in Kansas (291,269 acres) and 

Oregon (1 40,062 acres). Rye is planted in two states, Oklahoma (3 10,000 acres) and Georgia 

(230,000 acres). 

B. Exposure Characterization 

1. Environmental Fate and Transport Characterization 

Florasulam (XDE-570) does not hydrolyze at acid or neutral pHs, but hydrolyzes slowly 

(half-life of 99 days) at pH 9. The major hydrolysis degradates at pH 9 are N-(2,6-difluorpheny1)-8- 

fluoro-5-hydroxy (1,2,4)triazolo (13) pyrimidine-2-sulphonamide (5-OH-XDE-570) and a second 

hydrolysis product for which the structure was not confirmed. Florasulam photodegrades slowly 

(adjusted half-life of 46 days) in water. The only major degradate is triazolopyrimidine sulphonic 

acid of florasulam (TSPA). Florasulam is stable to photodegradation on soil. Abiotic degradation 

(by hydrolysis or photolysis) is not expected to be a significant route of dissipation in the 

environment. 

Florasulam is not persistent in aerobic soil, degrading rapidly in such, with half-lives of 0.7- 

8.3 days in 1 1 soils. The major degradates are 5-OH-XDE-570; N-(2,6-difluoropheny1)-5- 

aminosulphonyl- 1 H- l,2,4-triazole-3-carboxylic acid (DFP-ASTCA); 5-(aminosulphony1)- 1 H- 1,2,4- 

triazole-3-carboxylic acid (ASTCA); and 1H-1,2,4-triazole-3-sulphonamide (TSA). Based on the 

study results and the chemical structures, florasulam appears to biotransfonn rapidly to 5-OH-XDE570, which is then further biotransformed to DFP-ASTCA, DFP-TSA, and polar compounds, 

eventually forming C02 (range of 5-12%; mean of 9% for 7 soils) and bound residues (range of 15- 

57%, mean of 3 1 % for 1 1 soils). The major degradate 5-OH-XDE-570 degrades more slowly than 

the parent in aerobic soil, with half-lives ranging from 10 to 56 days in 11 soils, and is labile to 

moderately persistent. Biotransformation of florasulam is a significant route of dissipation in 

aerobic soils. Data were not submitted for anaerobic soils. 

In aquatic systems, florasulam degrades with half-lives of 3-1 8 days in aerobic systems and 

2-1 3 days in anaerobic systems. In aerobic aquatic systems, florasulam is biotransformed to 5-OHXDE-570, which is then further biotransformed to DFP-ASTCA and STCA (tentative 

identification). However, 5-OH-XDE-570 degrades much more slowly than the parent, degrading 

with a half-life of 169 days in one aerobic system and remaining stable in another aerobic system. In 

anaerobic aquatic systems, 5-OH-XDE-570 is stable. Thus, 5-OH-XDE-570 is expected to be 

persistent in both aerobic and anaerobic aquatic systems. 

There is a potential for florasulam to reach surface water through spray drift, as the 

compound may be applied by ground or aerial sprays. Because both the parent compound and 5- 
OH-XDE-570 are very mobile in soil, there is also the potential for them to reach surface water 

through runoff, although this potential will be somewhat decreased for the parent due to its rapid 

biodegradation in aerobic soil. For 5-OH-XDE-570, the potential to reach surface water through 

runoff is enhanced (relative to the parent) by slower biotransformation in aerobic soil. For both the 

parent and the degradate, however, the potential to reach surface water through runoff will be 

reduced by any leaching that occurs in the field. 

Based on the results from the laboratory batch equilibrium studies and column leaching 

studies, and supported by the results of multiple terrestrial field dissipation studies in which 

leaching was observed, both florasulam and 5-OH-XDE-570 are very mobile in soil and, thus, have 

the potential to leach to groundwater. In batch equilibrium studies, all measured Kds are less than 1. 

In an unaged column leaching study, most of the applied radioactivity leached through the soil 

columns (67.7 - 92.1 % of applied). The leachates contained 41.4 - 54.3 % of the applied parent 

compound and 21.5 - 39.2% of applied as 5-OH-XDE-570. The parent and the major degradate 

have been observed to leach in the field as well. In multiple terrestrial field dissipation studies, the 

parent compound leached to depths as low as 46 cm and 5-OH-XDE-570 leached as low as 61 cm. 

Greater leaching depths may have occurred, but in several of the studies, the depth of sampling was 

insufficient. For the parent compound, the potential to leach downward and to reach groundwater 

will be somewhat reduced by the fairly rapid biotransformation of the parent in aerobic soil. For 5- 

OH-XDE-570, the potential to leach is enhanced (relative to the parent) by slower biotransformation 

in aerobic soil and by a much higher solubility in water. For either compound, both of which 

partition mainly to the water phase, the potential to leach will be greater when there is excessive 

rainfall or irrigation, particularly if either of these occur close to the time of application. These 

concerns have also been identified in the Canadian and EU risk assessments for florasulam. 

Persistence and resulting accumulation of the parent compound is not expected in the field 

based on laboratory soil studies and terrestrial field dissipation studies. In the seven terrestrial field 

studies reviewed for this risk assessment (an additional 3 are still in review, but show similar 

trends), parent DT5Os were 2-19 days (mean of 8.0 days) and DT90s were 16-61 days (mean of 32.5 

days). At six of the sites, the parent was completely dissipated (to below the LOQ 0.01 -0.05 p/kg) 

from the surface soil by 2 months; at the 7' site it was approximately 20% of the initial 

concentration at 2 months and was completely dissipated by 122 days. 

The persistence and accumulation of 5-OH-XDE-570 is more variable than that of the 

parent, indicating that the compound may persist at some sites, but not others. At two sites in 

Canada, the compound was completely dissipated from the surface soil by 5 months; at the other 

two Canadian sites, 17% and 28% of the applied (in parent equivalents) remained at the end of the 

15-month studies. At two sites in France, the compound dissipated (i.e., fell below limits of 

quantitation) by 60 and 27 days, with respective half-lives of 17 and 9 days. In a study done in the 

United Kingdom, the compound was not completely dissipated until 122 days, with a half-life of 95 

days. 

Based on bioconcentration in fish (BCF) values of 0.9-2.OX, florasulam is not expected to 

bioaccumulate in aquatic organisms. 

Physical/chemical properties of florasulam and the major degradate 5-OH-XDE-570 are 

presented in Tables 3a and 3b. Table 4 lists other major degradates detected in the environmental 
fate studies. More complete information on the submitted environmental fate studies may be found 

in Appendix I. 

CAS: N-(2,6-difluropheny1)-8- 

fluoro-5- 

methoxy[l,2,4]triazolo[1,5- 

clpyrimidine-2 sulfonamide 

Chemical Name 

my in Water (20 

IUPAC: 2N,6N,8-trifluoro-5- 

methoxy-s-triazolo[1,5- 

clpyrimidine-2-sulphonanilide 

I I I 

Hydrolysis Half-life (pH 

Proposed label 

Molecular Weight Product Chemistry 

*H 9: 98-100 days (n=2) at 25 

"C and 2 19-226 days (n=2) at 

20 OC: 

359.3 

12 1 mg/L (unbuffered water) 

@ pH 5 = 0.084 g/L 

@pH 7 = 6.36 g/L 

@, pH 9 = 94.2 g/L 

2.7 x 10'~ Pa 

pH 5, 7: stable 

Aqueous Photolysis Halflife (@ pH 5; in days) 

Soil Photolysis Half-life I (days) 

Product Chemistry 

Product Chemistry 

MRID 46808130 

Half-life (days) 

Very soluble at all 

environmentally relevant 

pHs. 

Relatively non-volatile 

Anaerobic Soil 

Metabolism Half-life 

Metabolism Half-life 

Metabolism Half-life 

Coefficient (Kf or mean 

MRID 46808 132 Study conducted in 

natural light; corrected 

for light intensity, halflife is 46 days (40 ON in 

Stable 

I 46827910. 

Each value is an average 

half-life based on data 

0.7, 1.5, 1.7, 1.7,4.5; 

3.9, 8.3; 

1.0, 1.3; 

4.0, 6.0 

No data 

MRID 46808 134. 

MRIDs 46808 135 

(German and UK soils); 

46808138 (Canadian and 

UK soils); 46808 136 (UK 

soils); 46808 137 (UK 

soils) 

-- 

summer) 

Study conducted in 

natural light 

3 

2, 13 

Mean &: 0.08, 0.14,0.33,0.35, 

0.90,0.94 mL/g (associated Kf 

values: 0.13, 0.22,0.35,0.89, 

MRID 468279 1 1 

MRID 46808 140. 

MRID 46827912. 

1.4, 1.9 d/g) 

Mean &: 0.02,0.07,0.08,0.09, 

0.1,0.13,0.13,0.18,0.33 mL/g 

from two different labels. 

MRID 46808145. 
Table 3b. Physical/chemical properties and environmental fate source data for the 

florasulam major degradate 5-OH-XDE-57( 

Property -% 2, .., . 3. 

. YW4 :* .. . . , , 

Log Kow (pH 7) 

Henry's Law Constant 

PK~ 

Bioconcentration Factor 

in Fish (BCF) 

Chemical Name I N-(2,6difluorphenyl)-8- 

@pH4or5 - 1.00 

@ pH 7 -1.85 

@ pH 9 or 10 -2.06 

2.93 x 10~'~ atm mbol-' 

4.53 (pH 3.0-5.5) 

7.22 (pH 6.0-8.5) 

0.9-2.OX 

Product Chemistry 

Calculated 

Product chemistry 

MRID 46808322 

Molecular Weight 

Calculated from vapor 

pressure, solubility, and 

molecular weight; Nonvolatile from a water or 

moist soil surface. 

Neutral molecule will 

predominate at pH >4.53 

and anionic form will 

predominate at pH >7.22, 

so less adsorption 

expected at higher pHs. 

pyrimidine -2-sulphonamide 

341.3 

Solubility in Water (20 OC) 

Vapor Pressure (25 OC) 1 2.7 x 10.~ Pa 

Hydrolysis Half-life (pH 5, 1 stable 

Anaerobic Soil 

Metabolism Half-life 

Aqueous Photolysis Halflife (@ pH 5; in days) 

Soil Photolysis Half-life 

(days) 

Aerobic Soil Metabolism 

Half-life (days) 

No data 

Not available 

Not available 

10, 24,26, 29, 3 1; 

34, 56; 

(days) 

Aerobic Aquatic 1 169, stable 

~etabolism Half-life 

I (days) 

I 

Reviewer-calculated 

value. 

MFUDs 46808135 

(German and UK soils); 

46808138 (Canadian and 

UK soils); 46808 136 

(UK soils); 46808 137 

(UK soils) 

Product Chemistry. 

assumed 

estimated 

MRID 468279 1 1 In MRID 468279 10, data 

were too variable between 

labels to calculate a half-life I for one s stem, and the 

Very soluble at 

environmentally relevant 

pHs (and much more soluble 

than parent cmpd.). 

Same as parent cmpd. value 

Conservative estimate based 

on data from MRID 

46808 130. Compound 

reached its maximum levels 

(at pH 9) at the end of the 

90-day study. 
Anaerobic Aquatic 

Metabolism Half-life 

(days) 

Soil Adsorption 

Coefficient (Kd) 

Log Kow (pH 7) 

Henry's Law Constant 

PK~ 

Bioconcentration Factor in 

~ Fish (BCF) 

stable 

Kf: 0.07, 0.21,0.24, 0.69, 

1.55, 1.73 mL/g (mean Kds 

0.16, 0.20,0.23, 0.28,0.66, 

0.72 mL/g) 

@ pH 5 = 0.32 

@pH7= -1.85 

@, pH 9 = -2.32 

2.63 x Pa m3 mol-' 

4.53 (pH 3.0-5.5) 

7.22 (pH 6.0-8.5) 

No data 

MRID 46808 140. 

MRID 46827912. 

Product Chemistry 

estimated 

Product chemistry. 

- 

compound was stable in the 

second system. 

Calculated from vapor 

pressure, solub., and mol. 

wt.; non-volatile from a 

water or moist soil surface. 

Neutral molecule will 

predominate at pH ~4.53; 

anionic form will 

predominate at pH >7.22, so 

less adsorption expected at 

higher pHs 

- 
Degradate Structures 

Aerobic 

Aquatic 

Metabolism 

Anaerobic 

Aquatic 

Metabolism 

Terrestrial Field 

Dissipation 

'~e~radate data are included only for compounds which were degradates in the respective studies. 25-~~-~~~-570 = N-(2.6difluorphenyl)-8- 

fluoro-5-hydroxy (1,2,4)triazolo (1.5~) pyrimidine 2-sulphonamide; TPSA = (triazolopyrimidine sulphonic acid) of florasulam; DFP-ASTCA = N-(2.6- 

ditluorophenyl)-5-aminosulphonyl-lH-l.2,4triazole-3-carboxylic acid; ASTCA = 5-(aminosulphonyl)-lH-I,2,4-triazole-3-carboxylic acid; TSA = I H1,2,4-triazole-3-sulphonamide 

90-99% (60-1 00 

d); 77% (10 d) 

83-87% (97 d) 

2.98 uglkg (3 d); 

0.66 uglkg (14 d); 

1.77 uglkg (20 d); 

18-59% of 

applied (14-28 d) 

- 

- 

- 

- 

14.6% (100 d); 

30%(1 yr) 

- 

16-21% 

(1 yr) 

- 

- 

- 

MRIDs 

46827910, 

4680,8143, 

4628791 1 

MRID 

46808 140 

MRIDs 

46808 148, 

46808 149, 

46808 150, 

46808206 
DFP-TSA 

DFP-ASTCA 

ASTCA 

TSA 

2. Aquatic Exposure 

Modeling was conducted to estimate environmental concentrations of florasulam based on 

the proposed cereal grains use. Estimated Environmental Concentrations (EEC) of parent 

florasulam were determined using the Tier 1 screening-level model GENEEC2 (v.2.0; dated 

8/1/2002). 

Input parameter values used in this assessment were selected from the environmental fate 

data submitted by the registrant and in accordance with US EPA-OPP EFED water model parameter 

selection guidelines, Guidance for Selecting Input Parameters in Modeling the Environmental Fate 

and Transport of Pesticides, Version 11, February 28,2002. 

GENEEC2 is a screening-level model designed to estimate the pesticide concentrations 

found in surface water for use in ecological risk assessments. As such, the model provides upper 

bound estimates of the environmental concentrations (acute and longer-term) in surface water that 

might occur following the use of a pesticide. GENEEC2 uses basic environmental fate data ai-ld 

pesticide label use and application information to estimate the EECs following the treatment of a 

10-hectare field with subsequent runoff into an adjacent 1-hectare, 2-meter-deep "standard" pond 

with no outlet. GENEEC2 is a single event model (one runoff event), but can account for spray drift 

from multiple applications. In the model, the single runoff event occurs two days after the last 

application and can move a maximum of 10% of the applied pesticide into the pond, with the 
amount dependent on the degradation and adsorption of the pesticide which occurs in the field prior 

to the event. The model also accounts for degradation which may occur in the pond following the 

runoff event. Spray drift (resulting in direct deposition of the pesticide into the pond) in the model 

is equivalent to 1 % of the applied for ground spray application, and 5% for aerial. 

Tier I screening-level modeling was conducted using the maximum proposed application 

rate of 0.0045 lb ai/A for florasulam, applied once by aerial spray or ground spray application to 

foliage. Modeling input parameters used with the model GENEEC2 are presented in Table 5. The 

EFED defaults were used for droplet size and boom height, and refinements were modeled based on 

information in the "Use Precautions and Restrictions" section of the proposed label. 

Table 5. Input values used for estimating surface water concentrations with the Tier I model 

GENEEC2 based on florasulam use on cereal grains. 

Application Rate (lb a.i./A) 

Number of Applications 

Interval between Applications 

(days) 

Soil Partition Coefficient (b; mL/g) 

Aerobic Soil Metabolism Half-life 

(days) 

Wetted in? 

Depth of Incorporation (inches) 

Method of Application 

Solubility in Water @ 20 OC, 

unbuffered (mg/L or ppm) 

Aerobic Aquatic Metabolism Halflife (days) 

Hydrolysis Half-life @ pH 7 (days) 

0.0045 

1 

Not 

applicable 

0.02 

4.1 

No 

0 

Aerial or 

ground 

spray 

121 

19.3 

stable 

Proposed label. 

Proposed label. 

Not applicable 

MRIDs 

46827912 

46808 145 

MRIDs 

46808135 

46808138 

46808136 

46808137 

Proposed label. 

Proposed label. 

Proposed label. 

Product 

Chemistry. 

MRIDs 

46827910 

468279 10 

MRID 46808130 

- 

Assumed that maximum seasonal application 

was equal to maximum annual application for 

the crops listed on the proposed label. 

- 

Represents the lowest non-sand I& value 

among 9 mean & values ranging from 0.02 to 

0.33 mL/g or 6 mean I& values ranging from 

0.08 to 0.94 (with associated Kf values 

ranging from 0.13 to 1.9). 

Represents the 90' percentile of the upper 

confidence bound on the mean of 1 1 half-life 

values 

- 

- 

- 

- 

- 

Represents the 9oth percentile of the upper 

confidence bound on the mean of 3 half-life 

values 

- 
Tier 1 surface water modeling results for both ground spray and aerial spray applications of 

florasulam to cereal grains are presented in Table 6. Outputs include both estimated environmental 

concentrations (EECs) derived using the EFED default values and the refinements as noted in table 

footnotes and based on label restrictions. Complete output files are presented in Appendix 11. 

Aquatic Photolysis Half-life @ pH 

5 (days) 

Table 6. Maximum Estimated Environmental Concentrations (EECs) in surface water based on 

aerial and ground applications of florasulam to cereal grains. Results are reported in parts per 

46 

Aquatic Exposure Monitoring 

billion (ppb) and were estimated using the model GENEEC2. 

There are no U.S. monitoring data available for florasulam, which is not yet registered for 

use in the U.S. Monitoring data has reportedly been required as a condition of registration by some 

OECD member countries; however, these data are not yet available. 

MRID 46808 132 

Application 

Type 

Ground spray 

(w1EFED 

defaults1) 

Groundspray 

(wlrefinements) 

Aerial spray 

(wlEFED 

defaults2) 

Aerial spray 

(wlrefinements) 

3. Terrestrial Exposure 

Study was conducted in natural light; value is 

corrected for light intensity (40°N in 

summer). 

a) Animals 

Terrestrial wildlife exposure estimates are typically calculated for birds and mammals 

emphasizing a dietary uptake of pesticide through residues on vegetative and insect forage items. 

Avian terrestrial EECs are considered representative of potential exposure for terrestrial-phase 

amphibians and reptiles as well, unless more appropriate data are available through ECOTOX. For 

exposure to terrestrial organisms, pesticide residues on food items are estimated, based on the 

assumption that organisms are exposed to a single pesticide residue in a given exposure scenario. 

Exposure was evaluated using EECs generated from a spreadsheet-based screening model (TREX 

v. 1.3.1) that calculates the dissipation of a chemical applied to foliar surfaces for single or multiple 

 he EFED default for ground spray is "fine droplets"; the refinement is "medium to coarse droplets." 

 he EFED defaults for aerial spray are "high spray boom" and ''fine droplets"; the refinements are "low spray boom" 

and "coarse droplets." Refinements were selected based on proposed label "Use Precautions and Restrictions." 

Acute (ppb) 

0.1937 

0.1751 

0.20 17 

0.1926 

Maximum 4-day 

Concentration 

(PP~) 

0.1882 

0.1700 

0.1963 

0.1874 

Maximum 21- 

day 

Concentration 

(ppb) 

0.1602 

0.1446 

0.1671 

0.1595 

Maximum 60- 

day 

Concentration 

(ppb) 

0.1 145 

0.1033 

0.1 194 

0.1 140 

Maximum 90- 

day 

Concentration 

(ppb) 

0.0913 

0.0823 

0.0952 

0.0909 
applications. The terrestrial animal exposure assessment is based on the methods of Hoerger and 

Kenaga (1 972) as modified by Fletcher et al. (1994). When data are absent, as in this case, EFED 

assumes a 35-day foliar dissipation half-life. However, since only one application is modeled, the 

foliar dissipation half-life is not used in calculations for florasulam. The predicted maximum 

residues of florasulam that may be expected to occur on selected avian or mammalian food items 

immediately following application at the maximum rate for a single growing season are presented in 

Table 7. Since the number of growing seasons per year is not limited by the label, areas with 

multiple growing seasons could result in greater exposures on an annual basis. Further details of the 

model are presented in Appendix IV. 

Table 7. Unadjusted dietary-based estimated environmental concentrations (EECs) on terrestrial 

animal forage items following application of florasulam based on TREX (version 1.3.2). 

I 

Application Rate Food Items Upper-bound EEC Mean EEC 

(PP~)~ (PP~)" 

0.0045 lbs ai/A Short grass 

One application 

Tall grass 

I Broadleaf plants/small insects 0.61 0.20 

I Fruits, pods, seeds, and large insects 0.07 0.03 

a Predicted residues based on Hoerger and Kenaga (1972) as modified by Fletcher et al. (1994). 

b) Plants 

Exposure to upland and wetland plants is estimated using the TerrPlant (v1.2.2) screening 

model. TerrPlant estimates potential exposure from a single application using default assumptions 

for runoff and spray drift (Table 8). For runoff plus drift, TerrPlant incorporates two similar 

conceptual models for depicting dry and semi-aquatic areas of terrestrial habitats. For both models, 

a non-target area is adjacent to the treated field. Pesticide exposures to plants adjacent to the treated 

field are estimated to include runoff and drift from the treated field. For a dry area adjacent to the 

treated field, runoff exposure is estimated as sheet runoff. In the model, sheet runoff is defined as 

the amount of pesticide in water that runs off of the soil surface of a treated field which is equal in 

size to the non-target area (1 : 1 ratio of areas). For semi-aquatic areas, runoff exposure is estimated 

as channelized runoff. In the model, channelized runoff is the amount of pesticide that runs off of a 

treated field 10 times the size of the area adjacent to the treated field (1 0: 1 ratio of areas). The drift 

component is calculated as 1 % of applied mass (for ground spray) or 5% of applied mass (for aerial 

spray). Estimated exposures through runoff plus drift and drift alone are then compared to measures 

of plant survival and growth (e.g. effects to seedling emergence and vegetative vigor) to develop RQ 

values. See Appendix V for more information. 

Table 8. Estimated environmental concentrations (EECs) on plants following label-specified 

applications of florasulam determined using the TerrPlant model (lbs ai1A) - 

I Rate I Application Method I Adjacent Upland I Adjacent Wetland I Drift Only 

0.0045 lbs ai/A 

aLoading is runoff plus drift (lbs aiiA) 

Aerial 

Ground 

Loadings 

0.00045 

0.00027 

Loading 

0.00248 

0.00230 

0.00023 

0.00005 
C. Ecological Effects Characterization 

In screening-level ecological risk assessments, the effects characterization describes the 

types of effects a pesticide can potentially produce in an animal or plant. This characterization is 

typically based on registrant-submitted studies that describe acute and chronic effects information 

for various aquatic and terrestrial animals and plants; however, registrant-submitted data may also 

be supplemented by data reported in ECOTOX that have met Agency criteria for acceptability. 

Toxicity testing reported in this section does not include all species potentially affected by 

florasulam usage. Only a few surrogate species for fish, aquatic invertebrates and birds are used to 

represent all species in the United States. For mammals, effects are typically extrapolated from 

laboratory rat studies. Also, neither reptiles nor amphibians are tested. The risk assessment 

assumes that avian and reptilian and terrestrial-phase amphibian sensitivities to the chemical are 

similar. A similar assumption is made for fish and aquatic-phase amphibians. Terrestrial plant data 

are derived from the vegetative vigor and seedling emergence tests, typically on 10 agricultural crop 

species, and do not account for potential chronic or reproductive effects. Typically, five aquatic 

plant species are used to represent potential toxicity to all aquatic plant species. 

Most of the studies with non-target organisms were conducted with florasulam technical. 

The typical end-use product (TEP), EF-1343, was the test material in the terrestrial plant seedling 

emergence and vegetative vigor studies. These studies provide the effects basis for risk estimation. 

Further characterization is possible due the submission of non-guideline toxicity studies. The TEP 

was tested in a daphnid acute study, a rainbow trout acute study, a green algae biomass study, and 

four qualitative predatory and parasitic arthropod studies. The toxicity of 5-OH-XDE-570 was 

examined in an earthworm acute study, a daphnid acute study, a rainbow trout acute study and a 

green algae acute study. The transformation products DFP-ASTCA, ASTCA, TSA, STA and STCA 

were also tested in an acute earthworm study. None of the degradates demonstrated greater toxicity 

than the parent. The studies are summarized in this section; for more detail see Appendix 111. 

PMRA conducted the primary review of these studies; EFED conducted secondary review. , while 

generally consistent with PMRA, the OPP study classification is used in this document. A summary 

of the most sensitive endpoints in this risk assessment are presented in Table 9. 

Table 9. The most sensitive endpoints used in the florasulam risk estimation. 

Type Type of Environment Taxa Endpoint Units MRID of Risk Endpoint 

Freshwater 

Aquatic Fish Acute LC50 >lo0 mg ai/L 468083-13 

Chronic NOAEC 119 mg ai/L 

Freshwater 

Invertebrates Acute ECSO >292 mg ai/L 468083-1 5 

Chronic NOAEC 38.9 mg ai/L 468083-2 1 

Plants Acute EC5o 1.18 pg ai/L 468083-26 

Listed NOAEC 0.62 UE ai/L 468083-26 

Terrestrial Avian Acute LD5o 1047 mg aikg-bw 468083-05 

Chronic NOAEC 1500 mg aikg-diet 468083-08 

Mammalian Acute LDSO 6000 mg aikg-bw 468082-09 

Chronic NOAEC 100 mg aikg-bw 468082-35 
Type Type of Environment Taxa Endpoint Units of Risk Endpoint MRID 

Plants Acute ECzs 0.00005 lb ai/A 468083-24 

Listed NOAEC 0.000009 lb ai/A 468083-24 

1. Aquatic Effects 

a) Fresh water Fish 

In 96-hour acute static toxicity studies, rainbow trout (Oncorhynchus mykiss) and bluegill 

sunfish (Lepomis macrochirus) were exposed to florasulam at a concentration of 100 mg ai/L. No 

mortality or other adverse effects were observed. The 96-h LCSo and NOAEC values, based on 

mortality and non-lethal adverse effects, were >I00 and 100 mg ai/L, respectively. Florasulam is 

classified as practically non-toxic to freshwater fish on an acute exposure basis. 

The chronic toxicity of florasulam to rainbow trout was assessed in a 28-day fish early life 

stage toxicity study, conducted under flow-through conditions. The fish were exposed to meanmeasured concentrations of 9.6, 14.8,25.9,43.8,70.9 and 119 mg ai/L. Although there were three 

mortalities in the negative control, there were no mortalities or sublethal effects observed at any test 

concentration. The 28-day NOAEC was 1 19 mg ai/L. 

TEP and Transformation Products 

A 96-h acute toxicity study was conducted in which rainbow trout were exposed to the TEP, 

EF-1343, at a concentration of 100 mg EF-1343/L under semi-static conditions. No mortality or 

other adverse reactions were observed. The 96-h and NOAEC values, based on mortality and 

non-lethal adverse effects, were >lo0 and 100 mg EF- 1343/L, respectively. The formulated 

product, EF-1343, is classified as practically non-toxic to rainbow trout. 

In a 96-hour acute static toxicity study, rainbow trout were exposed to 5-hydroxy-XDE-570 

at a concentration of 100 mg ai/L. No mortality or other adverse reactions were observed. The 96- 

hour LCso and NOAEC values were >lo0 and 100 mg/L, respectively. The transformation product 

5-Hydroxy-XDE-570 is practically non-toxic to rainbow trout. 

b) Freshwater Invertebrates 

An acute 48-hour static toxicity study was conducted to determine the effects of florasulam 

on water fleas (Daphnia magna). The mean-measured test concentrations were 0 (control), 38, 63, 

104, 174 and 292 mg ai/L. At 48 hours, there was 20% immobilization observed at the highest 

concentration. No effects were observed at test concentrations of 174 mg ai/L and lower. 

Therefore, the 48-h ECS0 value was >292 and the 48-h NOAEC was 174 mg ai/L. Florasulam is 

classified as practically non-toxic to daphnids on an acute exposure basis. 

A chronic 21 -day (life-cycle) semi-static toxicity study was conducted to determine the 

effects of florasulam on daphnids. The nominal test concentrations were 0 (control), 14,23.3,38.9, 

64.8, 108, and 180 mg ai/L (mean-measured 13.7-1 76 mg ai/L), to which first instars were exposed. 
Ten replicates of one daphnid each were used to evaluate effects on reproduction and growth, and 

three replicates of five daphnids each were used to evaluate effects on mortality. The 21 -day 

NOAEC for the length and weight of adult daphnids was 38.9 mg ai/L. 

TEP and Transformation Products 

An acute 48-hour static toxicity study was conducted to determine the effects of the TEP, 

EF-1343 on daphnids. The daphnids were exposed to a single nominal concentration of 100 mg EF1343lL [(mean measured concentration was 5.5 mg ai/L (1 10% of nominal)]. No immobilization or 

other sub-lethal reactions were observed in the treatment for 48 hours. The 48-h ECSo and NOAEC 

were > 100 and 100 mg EF- 1343/L, respectively. EF- 1343 is classified as practically non-toxic to 

daphnids. 

An acute 48-hour static toxicity study was conducted to determine the effects of 5-hydroxyXDE-570 on daphnids. A single measured concentration of 96.7 mg ai/L was tested. No mortality 

or sublethal effects were observed over 48 hours. The 48-hour ECso and NOAEC values were >96.7 

and 96.7 mg aiIL, respectively. Therefore, 5-Hydroxy-XDE-570 is classified as practically nontoxic to daphnids. In another study, the acute toxicity of five transformation products of florasulam 

to daphnids was assessed over a 48-hour test period. Daphnids were exposed to two nominal 

concentrations of 3 and 30 pg ai/L each of DFP-ASTCA, ASTCA, TSA, STA, and STCA. There 

was no mortality or immobility observed following 48 hours of exposure to either of the two 

concentrations of any of the transformation products tested. The 48-hour ECSOs and NOAECs were 

>30 and 30 pg ai/L, respectively, for each of these transformation products. 

c) Estuarinemarine Fish 

In an acute static toxicity study, silverside (Menidia beryllina) were exposed to florasularn at 

a mean measured concentration of 122 mg ai/L, prepared with filtered natural sea water. No 

mortality or other adverse reactions were observed. The 96-hour LCso and NOAEC values were 

>I22 and 122 mg ai/L, respectively. Florasulam is classified as practically non-toxic to 

estuarinelmarine fish on an acute exposure basis. 

d) Estuarinemarine Invertebrates 

A 96-hour acute toxicity study was conducted under static conditions to determine the effect 

of florasulam on the grass shrimp (Palaemonetes pugio). The shmp were exposed to a mean 

measured concentration of 120 mg ailL prepared using natural sea water. There was no mortality or 

other adverse effects. The 96-hour LCsO and NOAEC were >I20 and 120 mg aiIL, respectively. 

Florasulam is classified as practically non-toxic to estuarinelmarine invertebrates on an acute 

exposure basis. 

e) Aquatic Plants 

In a 72-hour static laboratory toxicity test, the freshwater unicellular green alga, Selenastrum 

capricornutum, was exposed to the end-use product EF-1343 at mean measured concentrations of 0 

(control), 0.458, 0.92, 1.75,3.59, 6.9 and 11.9 pg ai1L. Exposure to EF-1343 at concentrations 

greater than or equal to 3.59 pg ai1L resulted in a significant reduction in both the average growth 

rate and the biomass compared to those of the control. The NOEC and ECSo values, based on 

biomass, were 1.75 and 3.45 pg aiIL, respectively. 

26 of 44 
In a 14-day static toxicity test, duckweed (Lemna gibba) was exposed to florasulam 

technical at measured concentrations of 0 (control), 0.137, 0.306,0.6 16, 1.35,2.3 and 4.59 pg ai/L. 

After 14 days, inhibition of growth ranged from -5.4% at 0.137 pg ai/L to 93.3% at 4.59 pg ai/L 

when compared to the solvent control. The NOEC and ECso values, based on frond number, were 

0.62 and 1 .18 pg aiIL, respectively. 

Transformation Products 

Cultures of the freshwater unicellular green alga, S. capricornutum, were exposed to 5-hydroxyXDE-570 at measured concentrations of 0 (control), 3.48,6.64, 13,25.4,49.5 and 96.1 mg/L under 

static conditions for up to 96 hours. Significant inhibition of growth was evident in cell count data 

at 13 mg/L and above. There were no other compound-related phytotoxic effects. The NOEC, EC2S 

and EC5() values, based on cell count, were 6.64, 1 1.59 and 25.57 mg 5-hydroxy-XDE-570/L, 

respectively. 

2. Terrestrial Effects 

a) Avian Acute Oral, Dietary and Chronic 

The acute oral toxicity of florasulam to 8-week-old Japanese quail (Coturnix japonica) was 

assessed over 14 days. Florasulam was administered to the birds by gavage in corn oil as a single 

oral dose at nominal concentrations of 0 (control), 175,292,486, 810, 1350 and 2250 mg aikg-bw. 

Toxic sublethal effects (lower limb weakness, wing droop, reduced reaction to sound and 

movement) were observed at 292 mg a.i./kg-bw and above, and were more severe at 2250 mg 

a.i./kg-bw. Mortality was 40,60, and 100 % in the 810, 1350, and 2250 mg ailkg treatments, 

respectively. The NOAEL (based on sublethal effects) and LDS0 were 175 and 1047 mg aikg-bw, 

respectively. Florasulam is classified as slightly toxic to Japanese quail on an acute oral exposure 

basis. 

The subacute dietary toxicity of florasulam to 1 1 -day-old Japanese quail and mallard duck 

(Anus platyrhynchos) was assessed over 8 days. Florasulam was administered to the birds in the 

diet at nominal levels of 0 (control), 3 12, 625, 1250,2500 and 5000 mg aikg diet. There were no 

compound-related toxic effects. The NOAEC and LCso were 5000 and >5000 mg aikg diet, 

respectively. Florasulam is classified as practically non-toxic to Japanese quail and mallard duck on 

a subacute dietary exposure basis. 

The chronic toxicity of florasulam to 20-week-old bobwhite quail (Colinus virginianus) and 

28-week-old mallard duck were assessed over 21 and 23 weeks, respectively. The adult bobwhite 

quail and mallard duck were fed diets containing florasulam at nominal concentrations of 0 

(control), 240, 600 and 1500 mg aikg diet prepared with the aid of acetone and corn oil. There 

were no compound-related toxic effects at any of the concentrations tested. The NOAEC for 

chronic toxicity to birds is 1500 mg aikg diet. 
b) Mammalian Acute and Chronic 

Florasulam is classified as practically non-toxic to rats (Rattus nowegicus; MRID 

46808209) with acute oral NOAEL and LDSO values of 6000 mg aikg-bw and >6000 mg aikg-bw, 

respectively. No adverse effects were observed at any of the doses tested. 

A 2-generation reproduction (MRID 46808235) study on rats reported a parental NOAEL of 

100 mg aiikg bwld and a NOAEL of 500 mg ailkg bwld for offspring and reproductive effects. The 

effects on the parental generation were reduced growth (weight loss) at the highest concentration 

tested. However, effects on these parameters were accompanied by an observed reduction in food 

consumption. Whether the reduced feed consumption was a result of a palatability issue or a 

chemical-induced anorexia is uncertain, although other chronic and subchronic studies (dog, rabbit) 

reviewed by the Health Effects division report similar observations. 

c) Nun-target Invertebrates 

Honeybees 

In a 48-hour acute oral toxicity study, honey bees (Apis mellifera) were exposed to 

florasulam via diet at the rate of 100 pg aihee. After 48 hours, 10% mortality was observed in the 

two replicate groups which had consumed the equivalent rate of 100 pg aihee. In the third replicate 

group, bees consumed only 80 pg aihee. Mortality in this group was 20%. The mortalities were 

not dose-related, but a NOAEC could not be estimated from these data. The was >I00 pg 

aihee; therefore, florasulam is classified as practically non-toxic to honeybees on an acute oral 

exposure basis. 

In a 48-hour acute contact toxicity study, honey bees were exposed to florasulam, 

administered topically at the nominal rates of 0 (control), 6.3, 12.5,25, 50 and 100 pg aihee. There 

was 5% mortality in both the negative and positive controls as well as the 100 pg aihee treatment 

level. The mortalities were not considered to be dose-related. The 48-hour NOAEC and LCs0 were, 

therefore, 100 and >I00 pg aihee, respectively. Florasulam is classified as practically non-toxic to 

honey bees on an acute contact exposure basis. 

Degradate and formulation toxicity 

For the major transformation products, two 14-day acute earthworm toxicity studies were 

conducted. In one study, earthworms were exposed to 5-hydroxy-XDE-570 at the measured rates of 

0 (control), 141,225, 399,678, and 1120 mg ailkg artificial soil. In another study, earthworms were 

exposed to each of the transformation products, DFP-ASTCA, ASTCA, TSA, STA, and STCA, at 

concentrations of 0 (control), 10 and 100 yg ailkg artificial soil. For the test with 5-hydroxy-XDE570, no significant mortalities or sub-lethal effects were observed in treatment and control groups 

during the 14-day exposure period. The NOEC and LC50 were 1 120 and >I120 mg aiikg soil, 

respectively. Survival of worms exposed to each of the other five transformation products averaged 

93 to 100% after 14 days. Thel4-day LCSOs were >I00 pg aikg. For sublethal effects, significant 

lethargy was noted at the 100 pg aikg treatment levels of DFP-ASTCA, ASTCA, and TSA at the 

end of the test. Therefore, the NOAEC values were 10 pg aikg for these three transformation 

products and 100 yg aikg for STA and STCA. 

28 of 44 
In addition to the above studies with the technical active, five studies were conducted with 

the TEP (EF-1343) to test the effect of the herbicide product on earthworms (one study) and honey 

bees (four studies). Results of these studies were consistent with the studies conducted with the 

technical florasulam, as no dose-related deleterious effects were noted in these studies. 

Four studies were also conducted to test the effect of the end-use formulation on the 

predatory green lacewing (one study), a predatory phytoseiid mite (one study), a parasitic wasp (one 

study) and a predatory carabid beetle (one study). These supplementary qualitative data did not 

demonstrate toxicity to these beneficial predators or parasites. 

d) Terrestrial Plants 

In a seedling emergence and 2 1 -day vegetative vigor laboratory toxicity test, a total of four 

monocotyledonous species [corn (Zea mays), oat (Avena sativa), onion (Allium cepa) and ryegrass 

(Lolium spp.)] and six dicotyledonous species [carrot (Daucus carota), cucumber (Cucumis sativus), 

radish (Raphanus sativus), soybean (Glycine max), sunflower (Helianthus annuus) and tomato 

(Lycopersicon esculentum)] were exposed to a single application of the TEP, EF-1343. The rates of 

EF-1343 (4.84% a.i.) applied to all species in both tests ranged from 0.00001 lbs ailA to 0.0089 lbs 

ailA (which bracket the proposed application rate of 0.0045 lbs a.i./A) in a natural soil. EF-1343 

demonstrated no statistically significant inhibition on the emergence, length or biomass of any 

species tested, except radish emergence. While the EC25 for radish is >0.0089 lbs aiIA, the NOEC 

is 0.001 1 lbs ai1A; for the remaining species tested, the NOAEC and EC25 are at treatment 

concentrations equivalent to application rates of 0.0089 and >0.0089 lbs a.i/A, respectively, 

In the vegetative vigor test, the most sensitive endpoints, based on an EC25 of 0.00005 lbs 

ai/A, were sunflower and tomato shoot length and carrot shoot weight (biomass). The NOEC, based 

on sunflower and tomato shoot length, was 0.000009 lbs ai1A. The other dicot species had EC25 

values ranging from 0.00006 lbs ai1A (tomato biomass) to 0.0015 lbs ai/A (soybean shoot length). 

Onion, a monocot, had an EC25 for biomass of 0.0006 lbs ailA and a NOEC of 0.0001 lbs ailA. The 

three grass species were unaffected in terms of biomass or shoot length, but all were reported to 

show visual signs of phytotoxicity (chlorosis, stunting) at 0.0089 lbs ailA, the highest treatment rate. 

While the grass species (Family: Poaceace) were tolerant of florasulam treatment, the other 

monocot tested, onion (Family: Liliaceae) was sensitive to florasulam. 

3. ECOTOX 

The Agency's publicly-available ECOTOX database (www) was reviewed 

for toxicological endpoints. There were no data on florasulam in the database when accessed 

0311 312007. 

Four open literature papers characterizing the efficacy and selectivity of florasulam were 

identified by ORD as passing the OPP and EFED ECOTOX relevance screen. In one of two papers 

on efficacy, Paterson et al. (2001) conducted field tests [conducted in four countries] of florasulam's 

effect on Galium aparine, a common weed species. The study found that while most G. aparine 

was controlled with at least 80% effectiveness (EC8O) at application rates between 0.0027 and 

0.0009 lbs ai/A (based on wet weight), four of the 20 test populations required an application rate as 
high as 0.0045 lbs ai/A to achieve control. In the second paper, Paterson et al. (2002) conducted a 

greenhouse study with field poppies (Papaver rhoeas) and reported an ECso range from 0.001 6 to 

0.0077 lbs ai/A, based on visual assessments. Three of the 15 populations studied required 

application rates greater than 0.0045 lbs ai/A. 

In the selectivity studies, Rijckaert and Lepiece (2003) applied florasulam to Festuca rubra 

and ryegrass (Lolium perenne) cultivars intended for grass seed production at 1 X and 2X the 

proposed label rate (0.0045 lbs ai/A) and found no significant difference in seed production or straw 

yield. Additionally, Rijckaert and Lepiece (2001) treated bentgrass (Agrostis stolonifera), fescue (F. 

rubra), prairie Junegrass (Koeleria macrantha) and Italian ryegrass (Lolium multzflorum) with 1X 

and 2X the proposed label rate and concluded that there was no significant difference in seed 

production or straw yield. These are desirable grass species and these studies are intended to 

emphasize that at the proposed application rate, florasulam will not adversely affect these species. 

111. RISK CHARACTERIZATION 

The risk quotient (RQ) approach is used in this assessment, comparing the ratio of exposure 

concentrations to effects endpoints with predetermined levels of concern (LOCs). Laboratory 

environmental fate, laboratory ecological effects, and use data that provide the basis for these risk 

quotients have been discussed previously in the assessment. Although risk is often defined as the 

likelihood and magnitude of adverse ecological effect, the risk quotient-based approach does not 

provide a quantitative estimate of likelihood andlor magnitude of an adverse effect. Estimated 

environmental concentrations (EECs) are divided by acute and chronic toxicity values to calculate 

RQs. If the RQs exceed the LOCs, the Agency presumes potential for risk to the taxa. These LOCs 

(Table 10) are the Agency's interpretive policy and are used to determine the need to consider 

regulatory action by indicating whether a pesticide, used as directed on the label, has the potential to 

cause adverse effects on non-target organisms. 

Table 10. Levels of concern (LOCs) for various taxa. 

Risk Presumption RQ LOC 

Birds 

Acute Risk EEC/LC50 or LDso/sqft or LDsdday 0.5 

Acute Restricted Use EEC/LCSo or LDSO/sqft or LDsdday (or LDsO < 50 mglkg) 0.2 

Acute Endangered Species EEC/LCSo or LD5a/sqft or LDsdday 0.1 

Chronic Risk EECNOAEC 1 

Wild Mammals 

Acute Risk EEC/LCSo or LD5dsqfi or LD,dday 0.5 

Acute Restricted Use EEC/LCSo or LDSdsqft or LD5dday (or LDS0 < 50 mgtkg) 0.2 

Acute Endangered Species EEC/LCSo or LD50/sqft or LD~dday 0.1 

Chronic Risk EECNOAEC 1 

I Aquatic Animals 

30 of 44 
Risk Presumption RQ LOC 

Acute Risk EEC/LCSo or ECsO 0.5 

Acute Restricted Use EEC/LCSo or ECSo 0.1 

Acute Endangered Species EEC/LCSo or ECS0 0.05 

Chronic Risk EEC/NOAEC 1 

Terrestrial and Semi-Aquatic Plants 

Acute Risk EECIEC25 1 

Acute Endangered Species EECNOAEC or ECoS 1 

Aquatic Plants 

Acute Risk EEC/ECSo 1 

Acute Endangered Species EEC/NOAEC or ECos 1 

A. Risk Estimation 

Based on the most sensitive endpoint for each of the taxa evaluated, only the RQ values for 

non-target terrestrial plants exceed the LOC for the proposed uses of florasularn. 

1. Aquatic Species 

a) Freshwater Fish 

Florasulam is classified as practically nontoxic on an acute exposure basis to freshwater fish, 

i.e. the LCso is greater than 100 mg/L, and the potential for acute risk to freshwater fish is presumed 

to be low. An RQ calculated using 100 mglL (the highest dose tested) is several orders of 

magnitude below (calculated RQ <2x10-~) even the acute risk to listed species LOC of 0.05. The 

RQ for chronic effects to freshwater fish is also orders of magnitude below (calculated RQ~lxlo-~) 

the chronic risk LOC of 1 .O. 

b) Fresh water In vertebrates 

Florasulam is classified as practically nontoxic on an acute exposure basis to freshwater 

invertebrates (LCso >292 mg/L), and the potential for acute risk to freshwater invertebrates is 

presumed to be low. RQs calculated from the most sensitive endpoint in the submitted studies are 

several orders of magnitude below (calculated ~~<6.9x1 o-~) even the acute risk to listed species 

LOC of 0.05. The RQ for chronic effects to freshwater invertebrates is also orders of magnitude 

below (calculated RQ<~X~ o-) the chronic risk LOC of 1 .O. 

c) Estuarine/Marine Fish 

Florasulam is classified as practically nontoxic on an acute exposure basis to 

estuarinelmarine fish, i.e. the LCso is greater than 100 mg/L, and the potential for acute risk to 

estuarinelmarine fish is presumed to be low. The RQ calculated using 100 mg/L (the highest dose 

tested) is several orders of magnitude below (calculated RQ<~x~o-~) even the acute risk to listed 

species LOC of 0.05. There are no chronic toxicity data available with which to calculate a chronic 
RQ for estuarinelmarine fish. 

d) Estuarinemarine Invertebrates 

Florasulam is classified as practically nontoxic on an acute exposure basis to 

estuarinelmarine invertebrates, i. e. the LC50 is greater than 100 mg/L, and the potential for acute risk 

to estuarinelrnarine invertebrates is presumed to be low. The RQ calculated using 100 mg/L (the 

highest dose tested) is several orders of magnitude below (calculated RQ<~x~o-~) even the acute 

risk to listed species LOC of 0.05. There are no chronic toxicity data available with which to 

calculate a chronic RQ for estuarinelmarine invertebrates. 

e) Aquatic Plants 

No RQ for aquatic plants exceeds the LOC. Using the highest modeled aquatic EEC (0.202 

ppb) for florasulam, the RQ for listed nonvascular aquatic plants is 0.17 and is well below the acute 

risk to listed species LOC of 1 .O. The RQ for listed vascular aquatic plants is 0.33 and is again 

below the acute risk LOC of 1 .O. Since protections for listed species are greater than for non-listed 

species, the presumption of low risk to listed species extends to non-listed species as well. 

2. Terrestrial 

a) Avian Acute and Chronic 

When both dose-based and dietary-based toxicity estimates are available for birds, acute risk 

quotients are calculated using both a dose-based and dietary-based approach. The dose-based RQs 

are calculated using a body weight-adjusted and consumption-weighted equivalent dose. The 

adjustments account for the fact that smaller-sized animals have to consume more food in terms of 

their body weight than larger animals and that differential amounts of food have to be consumed 

depending on the water content and nutritive value of the food. By expressing the Kenaga 

nomogram (Fletcher et al. 1994) estimated residues in terms of daily equivalent dose, estimated 

environmental concentrations can then be compared to the dose-based LD50. However, florasulam 

is classified as practically nontoxic to birds on a subacute dietary exposure basis; therefore, the 

potential for risk is presumed low. The most vulnerable birds (small birds foraging on short grass) 

with the greatest exposure have RQ values of <0.0002 based on the highest dietary concentration 

tested. While florasulam is classified as slightly toxic to birds on an acute oral exposure basis, the 

highest dose-based RQ is 0.001 6 and is two orders of magnitude lower than the acute risk to listed 

species LOC of 0.1. 

No effects on any adult, offspring or reproductive parameter were observed at the highest 

dose tested in the two submitted avian reproduction studies (NOAEC=l500 mgkg-diet). All 

chronic RQ values are ~0.01 and as such are more than two orders of magnitude below the chronic 

risk LOC of 1 .O. 

b) Mammalian Acute and Chronic 

No adverse effects were seen at the highest dose tested (6000 mg ailkg-bw) in the rat acute 

oral toxicity study, and florasulam is classified as practically nontoxic to mammals on an acute oral 

exposure basis; therefore, risk is presumed to be low. Using the highest dose tested, the highest RQ 

(small mammals foraging on short grass) would be <0.00009 and is well below the acute risk to 

listed species LOC of 0.1. 
Although parental effects were observed at the highest dose tested (500 mg ailkg-bw) in the 

rat reproduction study, no effects on reproductive or growth~survival of offspring were observed. 

Using the parental NOAEL (100 mg aikg-bw), all chronic mammalian RQs are <0.01 and are 

below the chronic risk LOC of 1 .O. 

c) Nontarget Plants 

RQs for upland plants (Table ll), as well as for monocots and unlisted dicots adjacent to the 

application site, are below the non-listed plant species LOC of 1 .O. RQs for listed dicots inhabiting 

wetlands exceed the listed species LOC of 1.0 by more than a factor of two for both aerial and 

ground applications. RQ values for non-listed monocots from drift alone do not exceed the LOC. 

The RQ for listed monocots is 2.25 when florasulam is applied aerially, but does not exceed the 

listed species LOC for ground application. The RQ for non-listed dicot species exposed to 

florasularn drift is 4.5 for aerial application, but the LOC for non-listed dicots is not exceeded for 

ground application. RQ values for listed dicot species from drift alone, 25 for aerial and 5.1 for 

ground, exceed the LOC for listed plant species. 

Table 11. Risk auotients for terrestrial ~lants from Termlant v1.2.2. I Application I Adjacent Upland I Adjacent Wetland 

Method 

Drift Only 

Nonlisted 

"bold indicates RQ exceeds LOC 

Listed 

Nonlisted 

Listed 

Because the use of florasularn indicates risk to plants using the default drift assumptions in 

TerrPlant, A~DRIFT@ was used to refine the drift assumptions and risk estimates. Using the EECs 

derived from the A~DRIFT@ model (v.2.01; default inputs), the RQ (1.1 ; Table 12) exceeds the 

LOC (1 -0) for non-listed species at 900 ft from the site of aerial application. The RQ for listed 

plants exceeds the LOC more than 6-fold. For ground applications, the RQ for non-listed plants 

(0.8; Table 13) is below the LOC at 100 fi from the application site, but the RQ for listed plants 

exceeds the LOC out to 500 ft from the treated field. 

Aerial 

Table 12. Terrestrial Plant RQs at Listed Distance from Site of Aerial Florasulam Application 

abold indicates RQ exceeds LOC 

Ground 

Monocot 

<0.05 

0.05 

c0.03 

0.03 

Dicot 

0.05 

0.41 

c0.03 

0.25 

Monocot 

<0.28 

0.28 

<0.26 

0.26 

Dicot 

c0.28 

2.25" 

c0.26 

2.09 

Monocot 

0.38 

Dicot 

4.50 

2.25 

0.08 

0.45 

25.3 

0.90 

5.06 
Table 13. Terrestrial Plant RQs at Listed Distance from Site of Ground Florasulam Application 

based on A~DRIFT@ Modeling. 

I Unlisted I Listed I - - r Distance EEC RQ RQ 

"bold indicates RQ exceeds LOC 

B. Risk Description 

Florasulam is being proposed for the post-emergent control of broadleaf weeds in wheat, 

barley, rye and triticale crops. The compound is not persistent in aerobic soils and degrades to 5- 

OH-XDE-570. Both florasulam and its primary degradate are very mobile. Florasulam can move to 

surface water through spraydrift. Although florasulam is not persistent in aerobic soils, the 

compound and its degradate can move to surface water through runoff or subsurface lateral flow 

following high rainfall events soon after application, and may leach into groundwater. The potential 

for leaching to groundwater is greater for the degradate, due to its greater persistence in aerobic soils 

and its much higher water solubility. 

Florasulam is practically nontoxic to aquatic and terrestrial animals on an acute exposure 

basis. Toxicity studies with florasulam degradates suggest that they are no more toxic than the 

parent. Consistent with the intended use of the compound as an herbicide, both aquatic and 

terrestrial plants exhibit a range of sensitivities to florasulam. 

In spite of the mobility of florasulam, estimated exposure concentrations combined with low 

toxicity to both terrestrial and aquatic animals result in RQ values below acute and chronic risk 

LOCs. However, the increased sensitivity of plants to florasulam results in RQ values which exceed 

LOCs for plants. Based on this baseline deterministic risk assessment, EFED cannot refute the risk 

hypothesis that the proposed label uses of florasulam may pose risk of adverse effects to non-target 

terrestrial plant species. Consistent with the risk hypothesis, potential direct risk to aquatic and 

terrestrial animals appears to be low. Contrary to the risk hypothesis, the potential for adverse 

effects to aquatic plants also appears to be low. However, indirect risk from potential changes in 

food availability or habitat through effects on plant populations or communities cannot be precluded 

and remains an uncertainty. 

1. Aquatic 

As presumed in the risk hypothesis, the potential for direct effects to aquatic animals from 

the use of florasulam appears to be low. RQs are at least four orders of magnitude below the listed 

species LOC for both acute and chronic effects to fish and invertebrates. However, because of the 

potential for florasulam to alter terrestrial plant communities, aquatic animals could be adversely 

affected through changes in habitat. These changes could include loss of spawning habitat, shelter 

or food sources, or increases in water temperature through reduction in stream-side shade plants. 

RQs for listed aquatic vascular and nonvascular plant species are well below the LOC of 1 .O. 
The application rate would need to be approximately 10X the proposed label rate of 0.0045 lbs ai/A 

for the listed nonvascular plant LOC to be exceeded, and roughly 3X the proposed label rate in order 

for the listed vascular plant LOC to be exceeded. Conversely, the NOAEC for aquatic vascular 

plants would need to be 113 the NOAEC from the Lemna gibba study for the LOC to be exceeded. 

While florasularn is not considered highly toxic to aquatic vascular plants based on the study 

submitted for this assessment, the guideline requirement is limited to a single study evaluating the 

response of Lemna gibba, a small monocot. Although not all monocots share the ability of wheat 

and some other grasses to rapidly degrade ALS inhibitors to less toxic forms, the degree to which 

the sensitivity of Lemna spp. is representative of other aquatic vascular plants is uncertain. 

Fairchild et al. (1 998), in a comparative study of several herbicides, reports that Lemna minor is of 

intermediates sensitivity, as much as five-fold less sensitive than other aquatic vascular plant species 

in the study. However, relative species sensitivity was dependent on the chemical used, and ALS 

inhibitors were not evaluated. If other species of aquatic vascular plants are more sensitive to 

florasulam than Lemna gibba, the potential for risk would be higher then indicated by the RQs 

derived for this assessment. 

2. Terrestrial 

Based on the analysis presented in this risk assessment, the potential for direct risk to listed 

and non-listed terrestrial animal species appears to be low. Calculated acute and chronic RQs, 

based on the upper-bound EECs, are several orders of magnitude below LOCs. The highest RQ for 

terrestrial animal species is 0.001 6 for small (20-g) birds foraging on short grass. While effects, 

including mortality, were observed in the avian acute oral toxicity study and sublethal effects on 

adult weight were observed in the chronic rat study, the EECs for florasulam are well below those 

effect thresholds. 

Toxic effects, including some mortality (20% or less), were observed in the bee studies, the 

effects occurred at the highest dose tested (100 pghee), and the LDS0 was >I00 pghee in both 

studies. However, EFED considers an LDjO > 11 pg/bee to indicate a chemical is practically 

nontoxic to bees; therefore risk to bees appears to be low. 

As expected with an herbicide, there is a potential for risk to listed and unlisted terrestrial 

plant species from the use of florasulam. While the only runoff-based RQs that exceed the LOC are 

for listed dicots in wetland habitats, variability in the seedling emergence study (as discussed below) 

introduces uncertainty as to whether the most sensitive endpoint was defined. Due to the nature of 

exposure in the vegetative vigor study (foliar spray), endpoints derived from that study are 

inappropriate for estimating risk from runoff exposure; only the seedling emergence results are used 

to evaluate potential risk from runoff. Since florasulam is a systemic herbicide, uptake through the 

roots is a potential source of exposure to plants, but current guideline studies do not address 

potential effects from this route of exposure. However, if effects were seen on vegetative vigor at 

the same exposure threshold via root uptake as via foliar spray, RQs would exceed the LOC for 

every category except upland monocots. 

While there was statistically no effect greater than 25% on the emergence, shoot length or 

biomass of any of the species tested in the seedling emergence study, several species (carrot, onion, 

soybean, cucumber, tomato) exhibited inhibitions ranging from 5% to 26% in these parameters at 

rates as low as 0.00001 lbs ai/A. The seedling emergence study was highly variable which likely 

35 of 44 
contributed to a lack of statistical power. Despite the fact that florasulam is not labeled as a preemergent herbicide, ALS inhibitors are typically most effective in actively growing plants, such as 

seedlings. Therefore, there may be potential for deleterious effects on sensitive non-target plant 

populations through decreased seedling emergence and possibly decreased vigor in the young 

seedlings. Because of the high degree of variability in the study, it cannot be definitively 

determined to what degree these effects may occur in the field. For instance, at 0.00001 lbs ai/A 

(the lowest dose tested), tomatoes exhibited a mean 26% reduction in biomass relative to the 

control, but at 0.0029 lbs ai/A, a mean 5% increase in biomass relative to the control was observed. 

The replicate coefficients of variance (CV) for the treatments ranged from 12.4% to 80.5%, while 

the control CV was 3.4%. This suggests that the control data are closely clustered and that the 

variability observed in the treatment groups is related to the chemical treatment. The variability in 

this study is a source of uncertainty in this assessment. 

Using the default assumption of fine-medium (ASTM S572) droplet size in AgDRIFT 

modeling, the LOC for terrestrial plants is exceeded even at 900 ft from the site when florasulam is 

applied aerially. The proposed label recommends that drift can be controlled by the use of larger 

droplet sizes, although it is not directive, stating that applications should be made "with a minimum 

of fine spray droplets." When medium-coarse and coarse-very coarse droplet-size spectra are 

modeled, the RQs are reduced (Table 14). For non-listed plants, increasing the droplet size to 

medium-coarse reduces the RQ below the LOC by 500 ft from the application site. When the 

coarse-very coarse droplet size is modeled, the LOC is not exceeded at 300 ft fiom the treated field. 

The LOC for listed species is exceeded at 900 ft (the limit of the model) from the treated field 

following aerial application regardless of the droplet size modeled, but is reduced by approximately 

half with each increase in droplet size (Table 15). 

Table 14. RQs for non-listed plants at listed distance from aerial application site of florasulam 

using various droplet-size spectra based on AgDRIFT EECs and the vegetative vigor endpoints. 

Droplet Size Spectrum (ASAE S572) 

Coarse-Very I Fine-Medium I Medium-Coarse I coarse 

"bold indicates exceeds LOC 

Distance 

100' 

300' 

Table 15. RQs for listed plants at listed distance from aerial application site of florasularn using 

various droplet-size spectra based on AgDRIFT EECs and the vegetative vigor endpoints. 

Droplet Size Spectrum (ASAE S572) 

Coarse-Very I Fine-Medium I Medium-Coarse I Coarse 

EEC 

0.0004 

0.0001 

RQ 

8.0a 

2.0 

Distance 

100' 

EEC 

0.0003 

0.000068 

EEC 

0.0004 

RQ 

6.0 

1.4 

RQ 

44.4a 

EEC 

0.0002 

0.000041 

EEC I RQ 

0.0003 1 33.3 

RQ 

4.0 

0.8 

EEC 

0.0002 

RQ 

22.2 
For ground applications (Table 16)' the LOC is not exceeded for non-listed plant species. 

The listed species LOC is exceeded out to 500 ft when the default (fine) droplet size is modeled. 

Using the medium-coarse droplet-size spectrum reduces the LOC exceedance to less than 300 ft 

from the treated field. 

-- - 

700' 

900' 

Table 16. RQs for listed and non-listed plants at specified distance from application site using a 

ground application of florasulam with various droplet-size spectra based on AgDRIFT EECs and the 

vegetative vigor endpoints. 

[ Droplet Size Spectrum (ASAE S572) 

abold indicates exceeds LOC 

0.000066 

0.000056 

I I Non-listed I Listed I Listed I 

7.3 

6.2 

"bold indicates exceeds LOC 

Distance 

Because the proposed florasulam label identifies a potential for the chemical to reach 

groundwater, potential risk to other crops irrigated with contaminated groundwater was considered. 

The highest modeled groundwater concentrations (from the Drinking Water Assessment, D332069), 

0.0135 ng/L, assuming 1 acre-inch of water, converts to an application rate of 3~10-~ lbs ai/A 

(Appendix VI). Using the most sensitive endpoint from the vegetative vigor study, the resulting 

RQ would be 0.0001 7; thus, risk to non-target crops from irrigation with contaminated groundwater 

appears to be low. Irrigation with surface water contaminated with florasulam at the EEC derived 

from GENEEC (0.202 ppb; see Aquatic Exposure) results in an RQ for sensitive plant species of 

2.6. Should undiluted irrigation return flow containing the modeled concentration of florasulam be 

used to irrigate sensitive crop species, there is a potential for crop damage. However, due to the 

conservative nature of the model and common agricultural practices regarding the target crops, 

irrigation with contaminated surface water is not likely. 

0.00003 

0.000026 

The PMRA assessment, from which this assessment draws support, uses visual phytotoxicity 

ratings as the most sensitive endpoints for terrestrial plant species. EFED uses visual ratings 

qualitatively for characterization, but not for RQ calculation. Risk estimation is based on growth, or 

occasionally survival, endpoints. Because visual signs of phytotoxicity are commonly apparent at 

lower treatment rates than growth or survival endpoints, the PMRA assessment uses lower EC25 and 

NOEC values in their assessment. Their assessment uses a vegetative vigor EQs of 0.00002 lbs 

ai/A (tomato) and an undefined NOEC of <0.00001 lbs ai/A (converted from 0.02 and <0.014 g 

ailha, respectively). Were non-listed plant RQs to be calculated with the visual phytotoxicity 

endpoint, the drift-only RQs for dicots would increase to 2.25 for ground application (up from 0.90) 

and 1 1.25 for aerial application (up from 4.5), while the listed species RQs would be undefined. 

37 of 44 

Fine-Medium 

EEC I RQ 

3.3 

2.9 

Fine-Medium 

EEC I RQ 

0.000018 

0.000014 

Medium-Coarse 

EEC I RQ 

2.0 

1.6 
While the PMRA assessment also uses lower endpoints for the seedling emergence study, RQs 

calculated with those endpoints are well below the LOC. 

Endocrine Disruption Screening 

The EPA is required under the FFDCA, as amended by FQPA, to develop a screening 

program to determine whether certain substances (including all pesticide active and other 

ingredients) "may have an effect in humans that is similar to an effectproduced by a naturally 

occurring estrogen, or other such endocrine effects as the Administrator may designate." 

Following the recommendations of its Endocrine Disruptor Screening and Testing Advisory 

Committee (EDSTAC), EPA determined that there was scientific basis for including, as part of the 

program, the androgen and thyroid hormone systems, in addition to the estrogen hormone system. 

EPA also adopted EDSTAC's recommendation that the Program include evaluations of potential 

effects in wildlife. For pesticide chemicals, EPA will use FIFRA and, to the extent that effects in 

wildlife may help determine whether a substance may have an effect in humans, FFDCA authority 

to require the wildlife evaluations. As the science develops and resources allow, screening of 

additional hormone systems may be added to the Endocrine Disruptor Screening Program (EDSP). 

When the appropriate screening andlor testing protocols being considered under the Agency's EDSP 

have been developed, florasulam may be subjected to additional screening and/or testing to better 

characterize effects related to endocrine disruption. 

Based on the available data, there are no indications that exposure to florasulam results in 

any effect on endocrine-mediated processes. 

C. Uncertainties and Data Gaps 

Environmental Fate Database 

The environmental fate database is relatively complete and constitutes a strong point in this 

assessment, as both the degradation (type and rate) and mobility of the pesticide have been well 

established. Acceptable studies have been submitted for hydrolysis, photolysis (aqueous and on 

soil), aquatic metabolism (anaerobic and aerobic), mobility in soil, and terrestrial field dissipation 

(one site). Although multiple aerobic soil metabolism studies were submitted, each was classified 

"supplemental" (with the exception of one classified "not acceptable"). The single aerobic soil 

metabolism study conducted with U.S. soils was classified "not acceptable;" none of the 

supplemental studies were conducted with U.S. soils. Because the parent degrades fairly rapidly, 

additional data for use in determining the half-life of the parent would not be likely to significantly 

decrease the uncertainty of the exposure assessment. However, additional aerobic soil metabolism 

data would add to the available information on the degradates, as the submitted studies were 

incomplete in that respect. 

Terrestrial field dissipation data were submitted from only one U.S. site. Although data for 

multiple foreign field sites were submitted, those studies were classified "supplemental" partially 

because the depth of sampling was insufficient to show the extent of leaching that may occur in the 

field for both the parent and 5-OH-XDE-570. Although the field dissipation studies conducted in 

the past were not necessarily designed to show the extent of leaching, newer guidelines allow for 

38 of 44 
separate modules to help distinguish between routes of dissipation such as leaching or runoff. For a 

cereal grains use, which covers a wide geographic area, data from additional U.S. sites would 

decrease the uncertainty inherent in using data from a single location to determine terrestrial 

dissipation rates. 

Environmental Effects 

The environmental effects database is largely complete and the effects on guideline taxa of 

exposure to the active ingredient the pesticide have been established. Additional data regarding 

degradates and formulation toxicity have been submitted. 

As discussed in the Risk Description, the seedling emergence study was highly variable 

which likely contributed to a lack of statistical power, adding uncertainty to the seedling emergence 

endpoints. The uncertainty is not thought to appreciably change the risk conclusions. 

There appears to be a range of sensitivities to florasulam across the plant species tested. 

While the guideline vegetative vigor study demonstrates variable sensitivity across a diverse set of 

species, the two Paterson et al. papers on efficacy show up to five-fold sensitivity within the species 

field poppies and over a three-fold difference in sensitivity within the weed species G. aparine. 

Neither species was more sensitive than the most sensitive species in the vegetative vigor study, as 

the studies were based on the EC8O. However, if the same variability in sensitivity is present in 

other species, it is possible that the endpoints used in this risk assessment do not represent the most 

sensitive ECZ5 values of the species tested. 

The toxicity of the degradates, especially 5-OH-XDE-570, to aquatic and terrestrial vascular 

plants is uncertain. Given that the parent is short-lived, the application rate is low, only one 

application is needed per season, and that the label has appreciable crop rotation restrictions, there 

may be herbicidal activity for longer than is suggested by fate properties of the parent alone. While 

submitted data indicate 5-OH-XDE-570 is less phytotoxic to unicellular algae than the parent, the 

parent is also less phytotoxic to unicellular algae than it is to Lemna gibba. There are no data 

submitted regarding the phytotoxicity of 5-OH-XDE-570 to terrestrial plants. Data submitted 

regarding the phytotoxicity of 5-OH-XDE-570 would reduce some of the uncertainty in this 

assessment. 

Although synergistic effects of tank mixes of active ingredients are not typically evaluated, it 

is possible that florasulam can exhibit greater phytotoxicity mixed with other herbicides than that 

evaluated in this assessment. Three of the four labels proposed for registration are for formulations 

containing other herbicides, and tank mixing is allowed on all the labels. In a patent application for 

an unrelated herbicide (US Patent 62971 97), Dow AgroSciences LLC states that one of the 

preferred tank mix chemicals for their new product is florasulam because there may be synergistic 

effects (httv://www.~atentstorm.us/~atents/6297 197-descriwtion.html; accessed 04.19.2007). 

General 

This assessment assumes one growing season per year, based on common agricultural 

practices. However, the number of growing seasons per year is not limited by the label; areas with 

multiple growing seasons could result in greater exposures on an annual basis. 

39 of 44 
IV. CONCLUSION 

This baseline risk assessment for the proposed use of florasulam on cereal grains indicates 

potential risk to terrestrial plants. There is a low potential for direct risk to aquatic plants, and 

aquatic and terrestrial animals, but there is a potential for indirect effects on these taxa based on 

florasulam's potential effect on primary productivity and habitat. 

V. THREATENED AND ENDANGERED SPECIES 

Levels of concern for threatened and endangered species are exceeded for terrestrial plants. 

Exceedance of LOCs for plants indicates concern for indirect effects on Federally-listed terrestrial 

animal species reliant on susceptible plant populations or communities, or those solely dependent on 

a sensitive plant for some portion of their life cycle (obligate relationships). 

The Overview of Ecological Risk Assessment Process in the Office of Pesticide Programs, 

U.S. Environmental Protection Agency (USEPA 2004, the 'Overview Document') discusses 

methods for providing the U.S. Fish and Wildlife Service (USFWS) and the National Marine 

Fisheries Service (NMFS), collectively 'the Services,' with additional information regarding the 

listed animal species acute levels of concern (LOCs). A tool has been developed by EFED in 

consultation with the Services to evaluate the chance of an individual organism being affected given 

the toxicity of the chemical to the organism and the dose-response curve (see Appendix VII for 

more detail). For the present time, the Excel spreadsheet tool IEC vl. 1 allows for such calculations 

by entering the mean slope estimate and the 95 percent confidence bounds of that estimate as the 

slope parameter for the spreadsheet. In cases where dose-response curves are unavailable, event 

probabilities are calculated for the listed species LOC based on a default slope assumption of 4.5 as 

per original Agency assumptions of typical slope cited in Urban and Cook (1986). 

The only animal toxicity study used in this risk assessment that reports mortality is the acute 

avian oral study. Since the only other mortality was observed in the acute oral bee study, which is 

not quantitatively evaluated by the Agency at this time, IEC modeling was only done for birds. For 

birds, the acute risk to listed species LOC is 0.1. The chance of one individual being affected at an 

RQ equal to the LOC is 1 in 294,000 (assuming the default slope). For birds, the highest acute RQ 

in this assessment is 0.001 6, for small-sized birds foraging on short grass. If listed birds are as 

sensitive to florasulam as the endpoint used in the model indicates, and exposed to the concentration 

modeled, the chance of an individual being affected is approximately 1 in 7.5~10"' or less. 

The screening-level risk assessment indicates that the acute risk LOC for terrestrial plants is 

exceeded. The Agency considers this to be indicative of a potential for adverse effects to those 

listed species that rely either on a specific plant species (plant species obligate) or multiple plant 

species (plant dependant) for some important aspect of their life cycle (indirect effects). Indirect 

effects may include general habitat modification, host plant loss, and food supply disruption. 

Further analysis regarding the overlap of individual species with each use site is required prior to 

determining the likelihood of potential impact to listed species. Such a refinement is outlined in the 

following sections. 

40 of 44 
A. Action Area 

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

directly or indirectly by the Federal action and not merely the immediate area involved in the action. 

At the initial screening level, the risk assessment considers broadly described taxonomic groups 

and so conservatively assumes that listed species within those broad groups are 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. 

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 could be 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 upon listed species that depend upon the taxonomic group covered by the RQ as a resource. 

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

LOCs for a given taxonomic group, a "may affect" designation cannot be precluded 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 need to be considered along with available information on the fate and 

transport properties of the pesticide to determine the extent to which screening assumptions 

regarding an action area apply to a particular listed organism. These subsequent refinement steps 

could delineate how this information would impact the action area for a particular listed organism 

and may potentially include areas of exposure that are downwind and downstream of the pesticide 

use site. 

B. Taxonomic Groups Potentially at Risk 

The RQs calculated based on the ratio of EECs to toxicity endpoints, in this case the 

NOAEC from terrestrial plant toxicity studies, exceed the LOC. Should estimated exposure levels 

occur in proximity to listed resources, direct risk to listed plant species and indirect effects on 

animal species (aquatic and terrestrial; Table 17) is possible. Appendix VIII provides a tabulation 

of species for each taxon that may be affected by this action. This Level I screening assessment is 

based on the initial assumption that listed species within the taxonomic groups of concern are 

actually present in areas for which the estimated exposure levels used for RQ calculation can be 

expected to occur. A specific determination of "may affect" for any RQ in excess of listed species 

LOCs cannot be made until a determination of the co-occurrence of the listed species with the action 

area has been determined. This was not done for this assessment. 

Table 17. Listed species risks associated with potential direct or indirect effects from to the 

proposed use of florasulam on cereal grains. 

Listed Taxon 

Terrestrial and semi-aquatic 

plants - monocots 

Direct Effects 

Acute 

Yes 

Direct Effects 

Chronic 

yes1 

Indirect Effects 
Terrestrial and semi-aquatic Yes plants - dicots I 

Insects 

Birds 

Terrestrial-phase amphibians 

Reptiles 

Mammals 

Aquatic plants 

Freshwater fish 

modification, host plant loss, and food supply disruption. 

No 

No 

No 

Aquatic-phase amphibians 

Freshwater invertebrates 

Mollusks 

Marinelestuarine fish 

Marinelestuarine crustaceans 

C. Indirect Effects Analysis 

No 

No 

No 

No 

Because terrestrial plant RQs are above risk to non-endangered species LOCs, the Agency 

considers this to be indicative of a potential for adverse effects to those listed species that are plant 

species obligates or plant dependant for some important aspect of their life cycle. The extent to that 

the new uses of florasulam will indirectly affect listed animal species will require identification of 

listed species that co-occur in areas of florasularn use and an evaluation of critical habit as described 

below. Because of the potential extent of the use of florasulam, EFED cannot preclude the 

possibility of a 'may affect' designation for listed species based on this assessment. 

No 

No 

 onli listed LOC exceeded for terrestrial plants, therefore there is potential for adverse effects to those species that rely 

either on a specific plant species or multiple plant species. Plant indirect effects may include general habitat 

No 

No 

No 

No 

No 

D. Critical Habitat 

yes' 

yes' 

yes' 

No 

No 

No 

No 

The screening-level risk assessment has identified potential concerns for direct and indirect 

effects on listed species associated with action areas where florasularn is used. In light of the 

potential for effects on listed species, the next step for EPA and the Services is to identi@ which 

listed species and critical habitat are potentially implicated. Analytically, the identification of such 

species and critical habitat can occur in either of two ways. First, the agencies could determine 

whether the action area overlaps critical habitat or the occupied range of each listed species. If so, 

42 of 44 

- 

yes' 

yes' 

yes' 

yes' 

No 

No 

No 

No 

No 

yes' 

yes' 

yes' 

yes' 

yes' 
EPA would examine the potential impact of the use of florasulam on listed species and whether 

impacts on non-endangered species would affect the listed species indirectly or directly affect a 

constituent element of the critical habitat. Then EPA would determine whether use of the pesticide 

overlaps the critical habitat or the occupied range of those listed species. At present, the 

information reviewed by EPA does not permit use of either analytical approach to make a definitive 

identification of species that are potentially impacted indirectly or critical habitats that are 

potentially impacted directly by the use of the pesticide. EPA and the Services will work together to 

conduct the necessary analysis. 

E. Co-occurrence Analysis 

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. At the screening level, this 

analysis is accomplished using the Agency's LOCATES (v. 2.10.3) database. The database uses 

location information for listed species at the county level and compares it to agricultural census data 

for crop production at the same county level of resolution. The database contains Federally-listed 

species that are located within states known to produce the crop upon which the pesticide will be 

used. Because the Level-I screening assessment considers both direct and indirect effects across 

generic taxonomic groupings, it is not possible to exclude any taxonomic group from a LOCATES 

database query for a screening-level risk assessment. 

Because the registration of florasulam would be the first in the U.S., the extent of its 

potential use has not yet been determined. As noted previously, at the screening level, it is not 

possible to evaluate all the potential direct and indirect effects that could impact endangered 

animals. Therefore, a 'may affect' designation cannot be precluded for listed animals based on this 

assessment. 
VI. REFERENCES 

Fairchild J. E., D. S. Ruessler, A. R. Carlson. 1998. Comparative sensitivity of five species of 

macrophytes and six species of algae to atrazine, metribuzin, alachlor, and metolachlor. Environ. 

toxicol. chem. 17:9, pp. 1830-1 834 

Fletcher, J.S., J.E. Nellessen, and T.G. Pfleeger. 1994. Literature review and evaluation of the EPA 

food-chain (Kenaga) nomogram, an instrument for estimating pesticide residues on plants. Environ. 

Toxicol. Chem. 13: 1383-1391. 

Hoerger, F. and E.E. Kenaga. 1972. Pesticide residues on plants: correlation of representative data 

as a basis for estimation of their magnitude in the environment. Environmental Quality and Safety. 

1 : 9-28. 

NASS. 2006. 2002 Census of Agriculture. U.S. Department of Agriculture, National Agricultural 

Statistics Service. Online at: http://www.nass.usda.gov/Census~~f~Agriculture/index.asp. Accessed 

on March 3,2007. 

Urban D.J. and N.J. Cook. 1986. Hazard Evaluation Division Standard Evaluation Procedure 

Ecological Risk Assessment. EPA 54019-85-001. U.S. Environmental Protection Agency, Office of 

Pesticide Programs, Washington, DC. 

USEPA. 2002. Guidance for Selecting Input Parameters in Modeling the Environmental Fate and 

Transport of Pesticides. U.S. Environmental Protection Agency, Office of Prevention, Pesticides 

and Toxic Substances, Office of Pesticide Programs, Environmental Fate and Effects Division. Feb. 

28, 2002. Online at: http://www.epa.gov/oppefed1/models/water/input_guidance2~28~02.htm/. 

USEPA. 2004. Overview of Ecological Risk Assessment Process in the Office of Pesticide 

Programs, U.S. Environmental Protection Agency. Office of Prevention, Pesticides and Toxic 

Substances, Office of Pesticide Programs, Washington, DC. 

USEPA. 2006. Water Models. U.S. Environmental Protection Agency, Pesticides: Science and 

Policy. Last updated May 2,2006. Online at: http://www.epa.gov/oppefedl/models/water/. 

Willis, Guye H., and Les1ie.L. McDowell. 1987. Pesticide Persistence on Foliage. in Reviews of 

Environmental Contamination and Toxicology. 100:23-73