1

UNITED STATES ENVIRONMENTAL PROTECTION AGENCY

WASHINGTON, D.C. 20460

OFFICE OF

CHEMICAL SAFETY AND

POLLUTION PREVENTION

Environmental Fate and Ecological Risk Assessment 

for the Proposed New Use of Spinosad

as a Commercial Seed Treatment

To control: seedcorn maggot and onion maggot in bulb vegetables, dried shelled pea and bean, 

cucurbit vegetables, and leaves of legume vegetables, 

Date: 09/13/2010

United States Environmental Protection Agency

Office of Pesticide Programs

Environmental Fate and Effects Division

Environmental Risk Branch V

1200 Pennsylvania Ave., NW 

Mail Code 7507P

Washington, DC 20460

Prepared by:

Joseph DeCant, 

Ecologist/Team Leader

Larry Liu, Chemist

Secondary Revision by: Mah 

Shamim

Approved by:

Mah T. Shamim, Chief

Environmental Risk Branch V
2

Table of Contents

1. Executive Summary................................................................................................................ 4

1.1 Nature of Chemical Stressor........................................................................................... 4

1.2 Potential Risk to Non-Target Organisms........................................................................ 4

1.3 Exposure Characterization.............................................................................................. 5

1.4 Effects Characterization.................................................................................................. 5

1.5 Data Gaps and Uncertainties........................................................................................... 6

2 Problem Formulation .............................................................................................................. 7

2.1 Nature of Regulatory Action........................................................................................... 7

2.2 Stressor Source and Distribution .................................................................................... 7

2.2.1 Nature of the Chemical Stressor ............................................................................. 7

2.2.2 Overview of Spinosad Usage................................................................................ 10

2.3 Receptors....................................................................................................................... 11

2.3.1 Aquatic and Terrestrial Receptors and Effects ..................................................... 11

2.3.2 Ecosystems Potentially at Risk ............................................................................. 12

2.4 Assessment Endpoints .................................................................................................. 12

2.5 Conceptual Model......................................................................................................... 13

2.5.1 Risk Hypothesis.................................................................................................... 13

2.5.2 Conceptual Diagram ............................................................................................. 14

2.6 Analysis Plan ................................................................................................................ 15

2.6.1 Methods of Conducting Ecological Risk Assessment and Identification of Data 

Gaps 15

2.6.2 Measures of Effect and Exposure ......................................................................... 19

3 Exposure Assessment............................................................................................................ 19

3.1 Aquatic Exposure Estimates......................................................................................... 22

3.2 Terrestrial Exposure Estimates..................................................................................... 23

4 Ecological Effects Assessment ............................................................................................. 24

4.1 Aquatic Effects Summary............................................................................................. 24

4.2 Terrestrial Effects Summary......................................................................................... 24

4.2.1 Toxicity Effects on Terrestrial animals................................................................. 24

4.2.2 Toxicity Effects on Invertebrates.......................................................................... 25

4.3 Incident Database Review............................................................................................. 26

5 Risk Characterization............................................................................................................ 26

5.1 Risk Estimation............................................................................................................. 27

5.1.1 Summary of Aquatic Risk Quotients.................................................................... 27

5.1.2 Summary of Terrestrial Risk Quotients................................................................ 27

5.2 Risk Description............................................................................................................ 29

5.2.1 Risk to Aquatic Organisms................................................................................... 29

5.2.2 Risk to Terrestrial Organisms............................................................................... 29

5.3 Endangered Species Assessment .................................................................................. 31

5.3.1 Probit Slope Analysis............................................................................................ 31

5.3.2 Direct and Indirect Effects.................................................................................... 32

5.4 Endocrine Disruption.................................................................................................... 32

5.5 Uncertainties................................................................................................................. 33
3

5.5.1 Exposure and Effects Assessment ........................................................................ 33

6 Bibliography ......................................................................................................................... 34

List of Tables

Table 1. Summary of physicochemical properties of spinosad. .................................................... 7

Table 2. Use information for the proposed use of spinosad on seeds as an insecticide................ 10

Table 3. Test Species Evaluated for Assessing Potential Ecological Effects of Spinosad.......... 11

Table 4. Environmental Fate Data Requirements for Spinosad................................................... 15

Table 5. Ecological Effects Data Requirements for Spinosad..................................................... 17

Table 6. Measures of Effect and Exposure for spinosad. ............................................................ 19

Table 7. EECs for the proposed use of spinosad as a seed treatment. .......................................... 22

Table 8. Toxic Effects in Terrestrial Animals Due to Acute and Chronic Exposure to Spinosad.

....................................................................................................................................................... 25

Table 9. Toxic Effects in Terrestrial Invertebrates. ...................................................................... 25

Table 10. Toxic Effects in Terrestrial Invertebrates in the Rhizosphere Due to Acute Exposure to 

Spinosad........................................................................................................................................ 26

Table 11. Ecological Incident Results as Listed by EIIS............................................................. 26

Table 12. Summary of Terrestrial Acute and Chronic Risk Quotients. Values in bold represent 

an exceedence of the respective LOC........................................................................................... 28

Table 13. Listed Species Risks Associated with the Proposed New Uses of Spinosad............... 32

List of Figures

Figure 1. Conceptual Diagram Depicting Potential Risks to Terrestrial and Aquatic Animals 

from the Use of Spinosad as a Seed-Treatment Insecticide.......................................................... 14

List of Appendices

Appendix A. TREX Methodology to Calculated Nagy Doses (EECs) and Risk Quotients for 

Birds and Mammals...................................................................................................................... 36

Appendix B. The Risk Quotient Method and Levels of Concern................................................. 37

Appendix C. Ecological Effects Data ........................................................................................... 38

Appendix D: Modeling Results for Aquatic Exposure ................................................................. 44

Appendix E. LOCATES Database Run for Endangered Species.Error! Bookmark not defined.
4

1. Executive Summary

The Environmental Fate and Effects Division (EFED) has completed its ecological risk 

assessment in support of the proposed new uses of Entrust® Naturalyte® (Spinosad as the active 

ingredient) to be used as a seed treatment to control seedcorn maggot and onion maggot in bulb 

vegetables, dried shelled pea and bean, cantaloupe, cucurbit vegetables (excluding cantaloupe, 

pumpkin, watermelon, winter squash), leaves of legume vegetables, pumpkin, winter squash, and 

watermelon.

1.1 Nature of Chemical Stressor

Spinosad is a mixture of spinosad Factor A and Factor D. Factor A and D are very similar in 

chemical structure as well as in fate properties. The difference between A and D is that Factor D 

contains an extra methyl group at carbon 4 on the central ring. Although the ratio between 

Factors A and D in spinosad could vary (50-95% vs. 50-5%, respectively), Factor A is the major 

component in spinosad. Since Factors A and D are very similar in nature and the registrant had 

submitted more information on Factor A than Factor D, EFED selected Factor A to represent 

spinosad in the ecological risk assessment. 

1.2 Potential Risk to Non-Target Organisms

The results of this screening-level risk assessment suggest that the proposed use of spinosad can 

pose acute and chronic risk to non-endangered, endangered, and threatened species of terrestrial 

organisms including birds and mammals, as well as to freshwater free-swimming and benthic 

sediment organisms. 

Risk to other aquatic animals, as well as terrestrial and aquatic plants, is based on previous risk 

assessments for mint and green onion as well as turf. The aquatic EEC’s in the current

assessment were similar to or lower than the previous assessment for turf (DP279684+), but 

higher than those for mint and green onion (DP310860+). In both assessments, chronic risk was 

found for freshwater free-swimming and benthic sediment dwelling invertebrates, but no risk 

was found for aquatic plants. Therefore, the proposed spinosad seed treatment would also pose 

risk to these freshwater animals and not to aquatic plants. No risk is present for terrestrial plants 

due to the low toxicity of spinosad to these organisms.

Acute risk was found in this assessment for small birds and mammals. However, there is 

uncertainty regarding the acute risk to birds due to the lack of definitive endpoints with avian 

species. For some crop uses, the lack of definitive endpoints means that the presumed risk is 

low. However, for bulb vegetables (crop group 3), foliage of legume vegetables (excluding 

soybean) (subgroup 7A), cantaloupe, cucurbit vegetables (crop group 9), pumpkin, winter 

squash, and watermelon, the EECs are greater than the highest dose tested in the acute toxicity 

studies for avian wildlife. The hazard of the chemical has not been evaluated at exposure levels 

above the highest dose tested in the acute toxicity study. While risk may be considered low for 

those uses that result in EECs less than the highest dose tested in the toxicity studies, risk cannot 

be precluded for these other uses. Therefore, acute risk to listed and non-listed birds cannot be 

precluded for bulb vegetables (crop group 3), foliage of legume vegetables (excluding soybean) 

(subgroup 7A), cantaloupe, cucurbit vegetables (crop group 9), pumpkin, winter squash, and 

watermelon. Acute risk to non-listed mammals was found for bulb vegetables (crop group 3),
5

cantaloupe, and cucurbit vegetables (crop group 9; excluding pumpkin, watermelon, winter 

squash), while acute risk to listed mammals was found for all uses except dried bean and shelled 

pea. All of the proposed uses pose a chronic risk to both birds and mammals, for which 

definitive endpoints are available.

The analysis shows that the proposed a.i./acre could be applied to a field at the maximum 

application rate per acre to pose a risk to endangered and threatened birds, so slightly lower 

application rates per acre would reduce the risk to these species. The application rate per seed, 

however, drives most of these risk conclusions and suggests that alternative rates could be 

explored to reduce the level of risk to birds and mammals on an acute and chronic basis. 

1.3 Exposure Characterization

Spinosad is proposed for a variety of crops as a seed treatment. Spinosad Factors A and D convert 

into transformation products that are very similar to the parent. in aerobic laboratory soil with 

half-lives of approximately 9-17 days. Under photolytic conditions, the parent readily forms 

transformation products in water with a half life of <1 day (pH 7) and on soil with a half life of 

about 10 days. The fate of the transformation products could not be determined due to 

termination of the study in 48 hours. Spinosad Factor A has a low to moderate water solubility 

and a low to slight mobility in sandy soils, and is immobile in silt loam and clay loam soils. 

Although no mobility data are available for Spinosad Factor D, it is 180x less soluble than Factor 

A and therefore would be expected to be less likely to leach in the soil. In terrestrial field 

dissipation studies with Spinosad Factor A on bareground plots, the half-life was <1 day, no 

leaching was observed, and 3.1% of the applied was recovered in runoff. The study did not 

follow the formation and decline of the transformation products and the half life may reflect the 

conversion of parent to transformation products or distribution of the parent and its residues in 

different environments. 

Spinosad has a high affinity for sediment and moves rapidly from the water to the sediment 

phases where it is highly persistent. In anaerobic aquatic metabolism studies, spinosad had a 

half-life of 161-250 days. In an aquatic microcosm dissipation outdoor study, spinosad residues 

in the sediment peaked at 8 days and had an observed half-life of >>25 days. Spinosad has a 

relatively low bio-concentration factor (BCF’s of the parent 7.5X, 28.8X, and 21.1X for muscle, 

viscera, and whole fish, respectively), and a relatively rapid rate of depuration (half-life of about 

one day). These factors generally would prevent substantial bio-concentration of the material in 

the food web.

1.4 Effects Characterization

Spinosad did not produce a definitive LC50 or LD50 in avian acute oral or dietary studies, with 

little mortality in the Bobwhite quail acute oral study and no mortality in the Mallard duck acute 

oral study. However, avian chronic effects included reductions in reproductive parameters (eggs 

laid, live 3-week embryos, normal hatchlings, 14 day-old survivors). The mammalian acute 

LD50 is 3738 mg/kg. Effects in chronic mammalian studies included reduced litter size, 

offspring body weights and survival of F2 generation. Developmental studies with rats and 

rabbits showed no evidence of toxicity. There was also no toxicity to earthworms in soil. Acute 

contact toxicity tests showed that spinosad is highly toxic toward honey bees when exposed to 

the TGAI. Tier I studies were submitted for seedling emergence and vegetative vigor testing. 
6

The TGAI or formulated product caused no phytotoxic effects to terrestrial plants greater than 

25%, thus no further plant testing is required. 

Spinosad is slightly toxic to rainbow trout and moderately toxic to bluegill sunfish on an acute 

basis. Data were submitted for the freshwater fish early life-stage test using rainbow trout. 

Significant reductions occurred in mean hatch, survival, and length and weight. Spinosad is 

categorized as moderately toxic to estuarine fish on an acute basis. Spinosad reduced growth in 

estuarine fish early life-stage testing. Spinosad is slightly toxic to freshwater invertebrates on an 

acute basis. Spinosad Factor B (the major transformation product of Factor A), is moderately 

toxic to daphnids on an acute basis. Data were submitted for a chronic test with Daphnia magna. 

Spinosad reduced daphnid growth and reproduction. Spinosad is categorized as highly toxic to 

mollusks on an acute basis. Spinosad reduced the number of young per female after 28 days of 

exposure in estuarine invertebrate life-cycle testing. Spinosad reduced adult emergence in 

sediment testing to chironomid larvae. The freshwater diatom is the most sensitive nonvascular 

aquatic species and the duckweed the most sensitive vascular species in aquatic plant tests. 

1.5 Data Gaps and Uncertainties

850.1735: Whole Sediment Acute Toxicity Invertebrates, Freshwater. This test measures 

survival, growth and emergence of Chironomus riparius that have been exposed to pesticide 

spiked sediment. EFED is not requesting this study at this time. Rather, EFED places this study 

in reserve.

850.1740: Whole Sediment Acute Toxicity Invertebrates, Estuarine and Marine - Testing 

with estuarine/marine invertebrates using the TGAI is required for spinosad because it is toxic to 

aquatic invertebrates, persistent in the environment, binds to sediment over time and the end-use 

product is expected to reach the marine/estuarine environment because of it use in coastal 

counties. A study to fulfill this guideline has recently been submitted but was found to be 

supplemental because it did not establish a definitive LC50. Data on a definitive endpoint to 

estuarine and marine invertebrates in sediment therefore remains and uncertainty.

850.2100: Acute Toxicity for Birds - For bulb vegetables (crop group 3), foliage of legume 

vegetables (excluding soybean) (subgroup 7A), cantaloupe, cucurbit vegetables (crop group 9), 

pumpkin, winter squash, and watermelon, the EECs are greater than the highest dose tested in 

the acute toxicity studies for avian wildlife. The hazard of the chemical has not been evaluated 

at exposure levels above the highest dose tested in the acute toxicity studies, which represents an 

uncertainty.

835.4200: Anaerobic Soil Metabolism - According to 40CFR Part 158 issued on 10/26/07, the 

registrant should submit an anaerobic soil metabolism (835.4200) study to support the terrestrial 

use.

Environmental Chemistry Method (ECM) and Independent Laboratory Validation (ILV) - 

According to 40CFR Part 158 issued on 10/26/07, the registrant should submit these studies to 

support terrestrial and aquatic filed dissipation studies.
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2 Problem Formulation

The purpose of this problem formulation is to provide the foundation for the environmental fate 

and ecological effects risk assessment being conducted for the seed treatment insecticide 

spinosad. Additionally, this problem formulation is intended to identify data gaps, uncertainties, 

and potential assumptions to address those uncertainties relative to characterizing the risk 

associated with the registered uses of spinosad, which is a synthetic pyrethroid with current uses 

as a foliar application. 

2.1 Nature of Regulatory Action

Under the authority of the Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA), Dow 

AgroSciences is seeking registration for the new uses of Spinosad as a seed-treatment insecticide 

in bulb vegetables, dried shelled pea and bean, cantaloupe, cucurbit vegetables (excluding 

cantaloupe, pumpkin, watermelon, winter squash), leaves of legume vegetables, pumpkin, winter 

squash, and watermelon. 

2.2 Stressor Source and Distribution

2.2.1 Nature of the Chemical Stressor

Spinosad belongs to the class of microbial insecticides. It is a secondary metabolite from the 

aerobic fermentation of S. spinosa on nutrient media. Spinosad is a mixture of two active 

naturally occurring metabolites (Spinosad Factors A and D) produced by the actinomycetes 

Saccharopolyspora spinosa. The IUPAC chemical name of Spinosad Factor A is: 

(2R,3aS,5aR,5bS,9S,13S,14R,16aS,16bR)-2-(6-deoxy-2,3,4-tri-O-methyl-∝-Lmannopyranosyloxy)-13-(4-dimethylamino-2,3,4,6-tetradeoxy-β-D-erythropyranosyloxy)-9-

ethyl-2,3,3a,5a,6,7,9,10,11,12,13,14,15,16a,16b-hexadecahydro-14-methyl-1H-8-

oxacyclododeca[b]as-indacene-7,15-dione. The IUPAC chemical name of Spinosad Factor D is: 

(2R,3aS,5aR,5bS,9S,13S,14R,16aS,16bR)-2-(6-deoxy-2,3,4-tri-O-methyl-∝-Lmannopyranosyloxy)-13-(4-dimethylamino-2,3,4,6-tetradeoxy-β-D-erythropyranosyloxy)-9-

ethyl-2,3,3a,5a,6,7,9,10,11,12,13,14,15,16a,16b-hexadecahydro-4,14-dimethyl-1H-8-

oxacyclododeca[b]as-indacene-7,15-dione. Trade names include Tracer, Naturalyte, and 

SpinTor.

Table 1. Summary of physicochemical properties of spinosad.

Spinosad A Spinosad D

CAS Registry Number 131929-60-7 131929-63-0

Emperical Formula C41H65NO10 C42H67NO10

Molecular Weight 731.976 745.988

Odor Slightly stale water or earthy

Relative Density (20°C) 0.512
8

Melting Point 84-99.5°C 161.5-170°C

Vapor Pressure (25°C) 2.4E-10 mmHg

3E-11 kPa

1.6E-10 mm Hg

2E-11 kPa

Octanol/Water Partition Coefficient 

(log Kow)

pH 5

pH 7

pH 9

Distilled water

2.78

4.01

5.16

3.91

3.23

4.53

5.21

4.38

Dissociaton Constant (pKa) (20°C) 8.10 7.87

Water Solubility (20°C)

pH 5

pH 7

pH 9

Distilled water

290 mg/L

235 mg/L

16 mg/L

89.4 mg/L

28.7 mg/l

0.332 mg/L

0.053 mg/L

0.495 mg/L

Solvent Solubility

Acetone

Acetonitrile

Dichloromethane

Methanol

Toluene

168.0 g/L

134.0 g/L

525.0 g/L

190.0 g/L

457 g/L

10.1 g/L

2.6 g/L

448.0 g/L

2.5 g/L

152 g/L

Spinosad is a mixture of spinosad Factor A and Factor D. The difference between A and D is 

that Factor D contains an extra methyl group at carbon 4 on the central ring. Although the ratio 

between spinosad A and D in spinosad varies (50-95% vs. 50-5%, respectively), the major 

component in spinosad is spinosad Factor A. Since spinosad Factor A and Factor D have very 

similar fate properties and the registrant had submitted more information on spinosad Factor A 

than spinosad Factor D, EFED selected spinosad Factor A to represent spinosad in the eco risk 

assessment. 

The primary mode of action of spinosad is the excitation of the neurons in the central nervous 

system (Salgado, 1998). Spinosad causes involuntary muscle contractions and tremors by 

widespread excitation of motor neurons. The prolonged hyperexcitation causes neuromuscular 

fatigue, resulting in paralysis. Within minutes of field application, insects are paralyzed and 

feeding ceases. Spinosad has limited translaminar movement in leaf tissue; however, the 

addition of a penetrating surfactant increases translaminar movement and activity on pests that 

forage leaves.

Aqueous photolysis (MRID 43507302)

At the end of the study (i.e., two days), approximately 75% of the applied dose was identified as 

the parent compound and transformation products 1, 2, and 3. Although the decline of the 

parent compound was established, the formation and decline of these three transformation 
9

products were not established because the study was terminated in two days. According to the 

report, transformation product 1 is the beta isomer of the 13,14-dihydro of the pseudoaglycone of 

the parent compound. Transformation product 2 is a rearrangement of the parent compound 

whereas transformation product 3 appears to be the parent compound with a water molecule 

added. The material balance at the end of the study was nearly 100% and a volatile trap was not 

used, EFED estimated nearly 25% of the material in the test system was not characterized at the 

end of the study. Therefore, the half-life for the total residues could not be calculated with 

confidence. 

Aerobic soil metabolism (MRID 43507305)

The extractability of spinosad residues in soil by the acetone/methanol system used in the study 

became less during the duration of the study, with non-extractable residues increasing to 43% 

after one year. At the end of the study, only 27% of the applied was tentatively identified or 

characterized as the parent compound as well as eight transformation products. Although these 

transformation products were not fully characterized or identified, the report suggested that they 

are likely to be of a similar nature to the parent compound. Due to the concerns on the 

effectiveness of the solvent system used, EFED was unable to estimate the half-life of the total 

residues based on their detections. However, based on the recovery of the volatile radioactivity, 

EFED estimated that the half-live for the residues in the soil could range 2-3 years.

Anaerobic aquatic metabolism (MRID 43507304)

Although the extractability of spinosad residues in soil by the acetone/methanol system used in 

the study became less during the duration of the study, the level of decrease is not as significant 

as that in the aerobic soil metabolism study mentioned above. The non-extractable residues in 

the sediment increased to 17% after one year in the anaerobic aquatic metabolism study as 

compared to 43% at the same time in the aerobic soil metabolism study. No explanation was 

provided in the reports regarding the differences in the extractability between the aerobic soil and 

the anaerobic aquatic metabolism studies. Four transformation products were tentatively 

identified or characterized whereas two were not identified in the anaerobic aquatic metabolism 

study. Since the report only provided information on the maximum concentrations found for 

these transformation products during the duration of the study and no detailed information on 

their detections at each sampling was provided, EFED was unable to calculate the half-life for 

the total residues. However, based on the residues recovered in the aqueous phase and the 

extracts in the sediment, EFED believes that the half-life for the total residues could be greater 

than three years.

Properties of Spinosad (Factor A and Factor D)

Below are the general fate properties of the parent compound only (spinosad Factor A and 

spinosad Factor D). This part was described in the eco risk assessment completed in 2002.

Spinosad Factors A and D convert into transformation products that are very similar to the parent

in aerobic laboratory soil with half-lives of approximately 9-17 days. Under photolytic 

conditions, the parent readily forms transformation products in water with a half life of <1 day 

(pH 7) and on soil with a half life of about 10 days. The fate of the transformation products 

could not be determined due to termination of the study in 48 hours. Spinosad Factor A has a 

low to moderate water solubility and a low to slight mobility in sandy soils, and is immobile in 

silt loam and clay loam soils. Although no mobility data are available for Spinosad Factor D, it 
10

is 180 times less soluble than Factor A and therefore would be expected to be less likely to leach 

in the soil. In terrestrial field dissipation studies with Spinosad Factor A on bareground plots, the 

half-life was <1 day, no leaching was observed, and 3.1% of the applied was recovered in runoff. 

The study did not follow the formation and decline of the transformation products and the half 

life may reflect the conversion of parent to transformation products or distribution of the parent 

and its residues in different environments. 

Spinosad has a high affinity for sediment and moves rapidly from the water to the sediment 

phases where it is highly persistent. In anaerobic aquatic metabolism studies, spinosad had a 

half-life of 161-250 days. In an aquatic microcosm dissipation outdoor study, spinosad residues 

in the sediment peaked at 8 days and had an observed half-life of >>25 days. Spinosad has a 

relatively low bio-concentration factor (BCF’s of the parent 7.5X, 28.8X, and 21.1X for muscle, 

viscera, and whole fish, respectively), and a relatively rapid rate of depuration (half-life of about 

one day). These factors generally would prevent substantial bio-concentration of the material in 

the food web.

2.2.2 Overview of Spinosad Usage

This assessment is intended to address the proposed new use of spinosad as a seed treatment for 

various crops. Entrust is a Naturalyte insect product for control of seedcorn maggot and onion 

maggot. This product may be applied as a seed treatment at a rate of 0.1-0.75 mg ai/seed or 0.02

-8.82 lb ai/100 lb seed. The proposed new registration includes use on a number of different 

crops.

The registrant is seeking a FIFRA Section 3 for the use of spinosad as a seed treatment. It serves 

as an insecticide in seed coating to protect the germinating seeds and seedlings. The crop, target 

pests, and relevant application information are summarized in Table 2. 

Table 2. Use information for the proposed use of spinosad on seeds as an insecticide.

Crop (Seeds) Pests

Entrust

(mg 

ai/seed)

Entrust

(lb ai/100 lb 

seed)

Maximum 

Seasonal 

Application 

Rate

(lb ai/acre)5

bulb vegetables (crop group 

3)1

onion maggot

seedcorn 

maggot

0.2 6.82 – 8.82 0.45

dried shelled pea and bean 

(except soybean) (subgroup 

6C)2 (excluding cowpea, 

lentils)

0.1 – 0.5 0.03 – 0.2 0.19

cantaloupe 0.5 – 0.75 2.31 – 3.47 0.45

cucurbit vegetables (crop 

group 9)3 (excluding 

cantaloupe, pumpkin, 

watermelon, winter squash)

0.70 – 3.77

foliage of legume vegetables 0.17 – 0.41
11

(excluding soybean) 

(subgroup 7A)4

pumpkin 0.83 – 1.24

Winter squash 0.55 – 0.83

watermelon 1.10 – 1.65 1

Bulb vegetables (crop group 3) including dry bulb onion, garlic, great-headed (elephant) garlic, green onion, leek, 

shallot, welch onion 2

Dried shelled pea and bean (except soybean) (subgroup 6C) including dried cultivars of bean Lupinus spp. (includes 

grain lupin, sweet lupin, white lupin, white sweet lupin), Phaseolus spp. (includes field bean, kidney bean, lima 

bean (dry), navy bean, pinto bean, tepary bean), bean Vigna spp. (includes adzuki bean, blackeyed pea, catjang, 

cowpea, crowder pea, moth bean, mung bean, rice bean, southern pea, urd bean), broad bean (dry), chickpea, guar, 

lablab bean, lentil, pea Pisum spp. (includes field pea), pigeon pea 3

Cucurbit vegetables (crop group 9) including cucumber, edible gourds, muskmelons (cantaloupe, honeydew, etc.), 

pumpkin, summer squash, watermelon, winter squash

4

Foliage of legume vegetables (subgroup 7A) including any cultivar of bean and field pea (except soybean) 5

The maximum seasonal application rate is the total of all methods of application – soil, foliar, and seed treatment.

2.3 Receptors 

2.3.1 Aquatic and Terrestrial Receptors and Effects

The receptor is a biological entity that is exposed to the stressor (US Environmental Protection 

Agency, 1998). As described in the risk assessment Overview Document (US EPA, 2004), this 

risk assessment uses a surrogate species approach in its evaluation of spinosad. Toxicological 

data generated from surrogate test species, which are intended to be representative of broad 

taxonomic groups, are used to extrapolate the potential effects on a variety of species (receptors) 

included under these taxonomic groupings. For example, the mallard duck and bobwhite quail 

are the preferred species in avian toxicity tests (acute and chronic) to represent toxicity for the 

entire class of bird species. 

Acute and chronic toxicity data from studies submitted by the registrant along with the available 

open literature are used to evaluate potential direct effects of pesticides to aquatic and terrestrial

receptors. These data include toxicity studies on the technical grade active ingredient (TGAI). 

The open literature are indentified through EPA’s ECOTOX database 

(http://cfpub.epa.gov/ecotox/), which employs a literature search engine for locating chemical 

toxicity data for aquatic and terrestrial floral and fauna. The evaluation of both sources of data 

provides insight into the direct and indirect effects of pesticides on biotic communities from the 

loss of species that are sensitive to the spinosad, and changes in structural and functional 

characteristics of the affected communities. A search of the ECOTOX database did not yield any 

relevant studies additional to those submitted by the registrant that would support this action. 

Table 3 provides examples of taxonomic groups and the surrogate species tested to help 

understand potential ecological effects of spinosad on these non-target taxonomic groups. 

Table 3. Test Species Evaluated for Assessing Potential Ecological Effects of Spinosad.

Taxonomic Group Example(s) of Surrogate 

Species Acute Toxicity Classification

Birds1 Mallard duck (Anas 

platyrhynchos)

Practically non-toxic on a dietary basis

to slightly toxic on a dose basis
12

Taxonomic Group Example(s) of Surrogate 

Species Acute Toxicity Classification

Bobwhite quail (Colinus 

virginianus)

Mammals Rat (Rattus norvegicus) Practically non-toxic

Freshwater Fish2

Bluegill sunfish (Lepomis 

macrochirus)

Rainbow trout 

(Oncorhynchus mykiss)

Fathead minnow 

(Pimephales promelas)

Moderately toxic

Freshwater 

Invertebrate Water flea (Daphnia magna) Slightly to moderately toxic

Estuarine/marine fish Sheepshead minnow 

(Cyprinodon variegates) Moderately toxic

Estuarine/marine 

invertebrates

Mysid shrimp (Mysidopsis 

bahia) Moderately toxic

Estuarine/marine 

mollusks

Eastern oyster (Crassotrea 

virginica) Very highly toxic

Terrestrial 

invertebrates Honey bees (Apis mellifera) Highly toxic

1

Birds represent surrogates for terrestrial-phase amphibians and reptiles 2

Freshwater fish serve as surrogates for aquatic-phase amphibians

2.3.2 Ecosystems Potentially at Risk

The ecosystems at risk from a stressor are often exclusive in scope, and as a result it may not be 

possible to indentify specific ecosystems at the baseline level. However, in general terms, 

terrestrial ecosystems potentially at risk could include the treated field and areas immediately 

adjacent to the treated field that may receive drift or runoff. Areas adjacent to the treated field 

could include other cultivated fields, fencerows, hedgerows, meadows, fallow fields or 

grasslands, woodlands, riparian habitats, and other uncultivated areas. 

Aquatic ecosystems potentially at risk from a stressor include water bodies adjacent to, or down 

stream from the treated field and might include impounded bodies such as ponds, lakes, and 

reservoirs, or flowing waterways such as streams or rivers. For uses in coastal areas, aquatic 

habitat also includes marine ecosystems, including estuaries. 

For spinosad, the terrestrial ecosystem primarily at risk is the rhizosphere zone in which treated 

seeds are planted on the crop field or due to the seed left (accidental spillage or otherwise) on 

soil surface at the time of planting. Seed-bound spinosad may pose risk to aquatic ecosystems 

through leaching, runoff, or erosion from the crop field. It is noted that for soil incorporated 

chemicals, or seed treatments, drift is usually a minor component.

2.4 Assessment Endpoints

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

an ecological entity (species, community, or other entity) and its attribute or characteristics (US 
13

Environmental Protection Agency 1998 and 2005). For spinosad, the ecological entities include 

the following: birds, mammals, terrestrial plants, insects, freshwater fish and invertebrates, 

estuarine/marine fish and invertebrates, aquatic plants, and algae. The assessment endpoints for 

each of these entities include survival, growth, and/or reproduction. This assessment will use the 

most sensitive toxicity measures of effect from surrogate test species to estimate treatmentrelated direct effects on acute mortality and chronic reproductive, growth, and survival 

assessment endpoints. 

2.5 Conceptual Model

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

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

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

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

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

A conceptual model is intended to provide a written description and visual representation of the 

predicted relationships between the stressor, potential routes of exposure, and the predicted 

effects for the assessment endpoint. A conceptual model consists of two major components: the 

risk hypothesis and the conceptual diagram (US Environmental Protection Agency 1998 and 

2005). 

2.5.1 Risk Hypothesis

Risk hypotheses are specific assumptions about potential adverse effects and may be based on 

theory and logic, empirical data, and mathematical models. For this assessment, the risk is 

stressor initiated where the stressor is the release of spinosad into the environment. The 

following risk hypothesis is presumed for this screening-level assessment:

The proposed new use of spinosad on bulb vegetables, dried shelled pea and bean, 

cantaloupe, cucurbit vegetables (excluding cantaloupe, pumpkin, watermelon, winter 

squash), leaves of legume vegetables, pumpkin, winter squash, and watermelon will likely 

involve situations where terrestrial and aquatic animals will be exposed to the chemical 

and or its transformation products. Based on information on environmental fate, mode of 

action, direct toxicity, and potential indirect effects, EFED assumes that spinosad may 

have the potential to cause reduced survival, growth, and reproduction to terrestrial and 

aquatic animals as a result of the proposed uses of the pesticide. 

The seedling emergence and vegetative vigor of non-target terrestrial plants and growth with 

biomass accumulation of aquatic plants adjacent to the site of spinosad application could be 

affected. The potential, however, is low as spinosad is not an herbicide and showed low toxicity 

to terrestrial plants. The previous assessment on turf with a higher application rate (DP279684+) 

also showed no risk concerns to aquatic and terrestrial plants. Furthermore, this new use 

addresses spinosad as a seed treatment, and therefore the risk to non-target plants is further 

mitigated through a decrease in exposure (i.e. reduction in drift and run-off). Risk to non-target 

plants is therefore not evaluated in this assessment, which relies instead on the results of the 

previous assessment on turf (DP279684+). 
14

2.5.2 Conceptual Diagram

The potential exposure pathways and effects of spinosad on terrestrial and aquatic environments 

are depicted in Figure 1. Solid arrows represent the most likely routes of exposure and effects 

for spinosad. 

Figure 1. Conceptual Diagram Depicting Potential Risks to Terrestrial and Aquatic 

Animals from the Use of Spinosad as a Seed-Treatment Insecticide.

Since spinosad is a seed treatment insecticide, ingestion of treated seed placed in soil and seed 

dropped on soil surface at the time of planting is the primary pathway through which exposure 

may occur for terrestrial wildlife (birds, mammals, and invertebrates). Other exposure routes 

such as dermal contact with treated seed and soil, inhalation of pesticide vapors, and ingestion of 

contaminated soil and drinking water are not evaluated in this assessment. Potential pathways of 

exposure to aquatic animals include dermal contact, uptake though gills, and/or dermal uptake 

through integument due to the offsite movement of spinosad to nearby water bodies. In view of 

the high tendency for spinosad to persist and accumulate in aquatic sediments, potential does 

exist for prolonged exposures to both aquatic and terrestrial organisms.

Stressor

Source/ 

Transport

Pathway

Source/ 

Exposure

Media

Exposure 

Method

Receptors

Direct

Effects: 

NonEndangered 

Species

Indirect

Effects

Food Web 

Dynamics

Perturbed Forage or 

Prey Availability

Habitat Alteration: impacts on nesting 

ability, ability to seek cover, etc.

Individual Terrestrial 

Animals

Reduced Survival

Reduced Growth

Reduced Reproduction

Individual Terrestrial 

Plants

Seedling Emergence

Vegetative Vigor

Individual Aquatic 

Vertebrates and 

Invertebrates

Reduced Survival

Reduced Growth

Reduced Reproduction

Aquatic Plant 

Population

Reduced

Growth Rates 

and Biomass

Terrestrial Animals

(Birds, Mammals, 

Reptiles, Terrestrialphase Amphibians, Bees)

Terrestrial 

Upland Plants

Wetland/ 

Riparian 

Plants

Runoff and Erosion

Upland 

Foliage/ 

Soil

Riparian/

Wetland 

Foliage/Soil

Surface 

Water, 

Sediment

Direct Contact/ 

Root Uptake

Gill/ Integument 

Uptake

Direct Contact/ 

Root Uptake

Ground

water

Direct 

Ingestion

Aquatic Invertebrates

Aquatic Vertebrates 

Aquatic Plants

Leaching

(Infiltration/ 

Percolation)

Terrestrial Food 

Residues 

(foliage, fruit, 

insects)/Soil

Dietary 

uptake

Seed Treated with Spinosad and Planted in Soil or Left on Soil Surface
15

This assessment to terrestrial animals considers environmental exposure resulting from treated 

seed only and is not based on root uptake of spinosad by plants. Data on the movement and 

accumulation of spinosad in plants is not available. Even if spinosad translocates and 

accumulates in plants, its concentrations will be lower than those available on the seed. 

Furthermore, spinosad is not classified as an herbicide so its toxic effects to plants are likely 

minimal. Therefore, the most conservative exposure estimate will result from ingestion of the 

treated seed rather than movement to foliage and within the plant. 

2.6 Analysis Plan

2.6.1 Methods of Conducting Ecological Risk Assessment and 

Identification of Data Gaps

This document characterizes the environmental fate and effects of spinosad to assess whether the 

proposed label new use of the compound results in risk to non-target organisms at levels above 

the Agency’s LOCs. The primary method used to assess risk in this screening-level assessment 

is the risk quotient (RQ). The RQ is the result of comparing measures of exposure to measures 

of effect. A commonly used measure of exposure is the estimated exposure concentration (EEC) 

and commonly used measures of effect include toxicity values such as LD50 or NOAEC. The 

resulting RQ is then compared to a specified level of concern (LOC), which represents a point of 

departure for concern, i.e. if the RQ exceeds the LOC, then risks are triggered. Although not 

necessarily a true estimate of risk since there is no estimated probability of effect, in general, the 

higher the RQ, the more certain the potential risks. 

The registrant has submitted additional information for terrestrial field dissipation, fish 

accumulation, aerobic aquatic metabolism, and aquatic dissipation studies. These data are under 

review. According to 40CFR Part 158 issued on 10/26/07, the registrant should submit the 

following studies: (1) anaerobic soil metabolismat (835.4200) study; (2) Environmental 

chemistry method (ECM) for soil and water; and (3) Independent laboratory validation (ILV) to 

support the terrestrial and aquatic uses.

Whole sediment acute toxicity testing for freshwater and estuarine/marine invertebrates is 

needed due to toxicity concerns for benthic organisms, persistence in aquatic environments, 

binding to sediment.

Table 4 summarizes the environmental fate data requirements for spinosad according to 40 CFR 

Part 158 Subpart N. Studies that have been received or not yet received will be noted as such in 

the table.

Table 4. Environmental Fate Data Requirements for Spinosad.

Guideline Number Data Requirement MRID Study Classification Is more data needed?

161-1 835.2120 Hydrolysis 43507301 ACCEPTABLE No

161-2 835.2240 Photodegradation in 

Water

43507302 ACCEPTABLE No

161-2 835.2240 Photodegradation in 

Water

44597735 ACCEPTABLE No
16

Guideline Number Data Requirement MRID Study Classification Is more data needed?

161-3 835.2410 Photodegradation on 

Soil

43507302 ACCEPTABLE No

161-3 835.2410 Photodegradation on 

Soil

43507303 ACCEPTABLE No

161-4 835.2370 Photodegradation in Air --- WAIVED No162-1 835.4100 Aerobic Soil 

Metabolism

43507304 ACCEPTABLE No

162-2 835.4200 Anaerobic Soil 

Metabolism

--- No data Yes

162-3 835.4400 Anaerobic Aquatic 

Metabolism

43507305 ACCEPTABLE No

162-4 835.4300 Aerobic Aquatic 

Metabolism

46642701

47908501

Unacceptable

Under review

Pending on the review

163-1 835.1240 Adsorption/Desorption 43507306 ACCEPTABLE No

163-1 835.1240 Adsorption/Desorption 43816602 ACCEPTABLE No

163-2 835.1410 Volatility (Lab) --- Waived No 

163-3 835.8100 Volatility (Field) --- Waived No

164-1 835.6100 Terrestrial Field 

Dissipation

43714301 SUPPLEMENTAL

Additional data were 

submitted and they are 

under review

Pending on the review

164-2 835.6200 Aquatic Field 

Dissipation

47420102 Under review Pending on the review

164-3 835.6300 Forestry Dissipation --- N/A No

164-4 835.6400 Combination and tank 

mixes Dissipation

--- Waived No

165-4 850.1730 Fish BCF 43557601 SUPPLEMENTAL

Additional data were 

submitted and they are 

under review 

Pending on the review 

165-4 850.1730 Fish BCF 44537734 SUPPLEMENTAL

Additional data were 

submitted and they are 

under review 

Pending on the review

165-5 850.1950 Accumulation - Aquatic 

Nontarget

--- Waived No

166-1 835.7100 Ground Water 

Monitoring Prospective

--- Waived No

201-1 840.1100 Droplet Size Spectrum --- Waived No

202-1 840.1200 Drift Field Evaluation --- Waived No

-- -- Environmental 

chemistry method 

(ECM)

--- No data Yes

-- -- Independent laboratory 

validation (ILV) --- No data Yes
17

Guideline Number Data Requirement MRID Study Classification Is more data needed?

Non-guideline Aquatic microcosm 

dissipation

43848803 SUPPLEMENTAL Spinosad (480 g/L suspension concentrate, 

ratio of A:D about 85:15) was surfaceapplied at 100g/ha to surface to outdoor tanks 

containing pond water. Parent spinosad 

dissipated from the water with a half-life of 

1.5 days. Total spinosad residues dissipated 

from the water with half-life of 4 days. In the 

clay loam sediment, spinosad Factors A and 

B were maximum averages of 14.9 ppb (4 

days) and 11.1 ppb (15 days), respectively; 

Spinosad Factor D was ≤4.2 ppb and Factor 

B of D was not detected. Maximum total 

spinosad residues in sediment were 56.0 ppb 

(8 days). 

Table 5 summarizes the data requirements for spinosad according to 40 CFR Part 158 Subpart 

G. Studies that have been received or not yet received will be noted as such in the table.

Table 5. Ecological Effects Data Requirements for Spinosad.

OPPTS 

Guideline # 

Data Requirement MRID # Classification Is more data needed?

850.2100 Avian acute oral LD50

(mallard duck)

(bobwhite quail)

434145-29

434145-28

Supplemental

Supplemental

No

No

850.2200 Avian subacute dietary LC50

(bobwhite quail)

(mallard duck)

434145-31

434145-30

Acceptable

Acceptable

No

No

850.2300 Avian reproduction 

(bobwhite quail)

(mallard duck)

434145-33

434145-32

Acceptable

Acceptable

No 

No

850.1075 Freshwater fish acute LC500

(rainbow trout)

TGAI

DEG

(bluegill sunfish)

TGAI

434441-03

434145-34

Acceptable

Acceptable

No

No

850.1010 Freshwater invertebrate acute EC50

(daphnia)

TGAI

DEG

434145-37

445977-31

465053-12

465053-04

465053-07

465053-09

Acceptable

Supplemental

Acceptable

Acceptable

Acceptable

Acceptable

No

No

No

No

No

No

850.1735 

Freshwater Invertebrate Sediment 

ToxicityTGAI N/A N/A Yes

850.1740 Marine Invertebrate Sediment 

ToxicityTGAI

47702901 Supplemental No

850.1075 Estuarine/marine fish acute LC50

(sheepshead minnow) 434145-40 Acceptable No
18

OPPTS 

Guideline # 

Data Requirement MRID # Classification Is more data needed?

850.1025

850.1035

Estuarine/marine invertebrate acute EC50

(eastern oyster)

(mysid)

(other)

434441-04/435712-03

434145-39

Acceptable

Supplemental

No

No

850.1400 Freshwater fish early life stage 434145-41 Acceptable No

850.1300 Freshwater invertebrate life cycle 

(daphnia)

DEG

465053-03

465053-06

465053-01

465053-11

Supplemental

Supplemental

Invalid

Invalid

No

No

No

No

850.1400 Estuarine/marine fish early life stage 444206-01 Acceptable No

850.1350 Estuarine/marine life cycle

(mysid) 444206-02 Acceptable No

850.1950 Aquatic Field Study N/A N/A N/A

870.1100 Acute mammalian oral LD50

(rat)

(rat)

437707-01

434145-15

Acceptable

Acceptable

No

No

870.4100 Mammalian Chronic

(rat) 437015-06 Acceptable No

850.4100 Seedling Emergence - Tier I 438488-02 Acceptable No

850.4150 Vegetative Vigor - Tier I 445977-32 Acceptable No

850.5400 Aquatic plant algae

TGAI

434145-42

434145-43

434145-44

434145-45

434145-46

Acceptable

Acceptable

Acceptable

Acceptable

Acceptable

No

No

No

No

No

850.4400 Aquatic plant acute EC50

DEG

465053-10

465053-08

465053-05

465053-02

Supplemental

Supplemental

Supplemental

Supplemental

No

No

No

No

850.3020 Acute honey bee contact LD50 434145-47

453408-01

Acceptable

Invalid

No

No

850.3030 Honey Bee Residue on Foliage 450077-01

450077-02

450077-03

Acceptable

Supplemental

Invalid

No

No

No

850.3040 Honey Bee Field Testing for Pollinators 457082-01

457088-01

Supplemental

Supplemental

No

No

Non-guideline 

Earthworm Chronic

Midge Chronic 

21 day tox to Rainbow trout (DEG)

28 day Midge Sediment Chronic (DEG)

28 day Midge Sediment Chronic (DEG)

28 day Midge Sediment Chronic (DEG)

28 day Midge Sediment Chronic (DEG)

434145-48

448284-02

465053-13

465053-14

465053-15

465053-16

465053-17

Supplemental

Supplemental

Supplemental

Supplemental

Supplemental

Supplemental

Supplemental

No

No

No

No

No

No

No
19

2.6.2 Measures of Effect and Exposure

Table 6 lists the measures of environmental exposure and ecological effects used to assess the 

potential risks of spinosad to non-target organisms in this assessment based on the concerns in 

the problem formulation. The methods used to assess the risk are consistent with those outlined 

in the document “Overview of the Ecological Risk Assessment Process in the Office of Pesticide 

Programs.” (2004)

Table 6. Measures of Effect and Exposure for spinosad.

Assessment Endpoint

Surrogate Species and 

Measures of Ecological 

Effect1

Measures of Exposure

Birds2

Survival

- Mallard duck acute oral LD50

- Bobwhite quail and mallard duck 

subacute dietary LC50

Maximum residues on seed and 

soil

Reproduction 

and growth

Mallard duck and bobwhite quail 

chronic reproduction NOAEL

Mammals

Survival Laboratory rat acute oral LD50

Reproduction 

and growth

Laboratory rat chronic 

reproduction NOAEL 1

If species listed in this table represent most commonly encountered species from registrant-submitted studies, risk 

assessment guidance indicates most sensitive tested within taxonomic group are to be used for baseline risk 

assessments

2

Birds represent surrogates for terrestrial phase amphibians and reptiles

3 Exposure Assessment

Environmental fate data and modeling results indicate that spinosad residues can be expected to 

dissipate very slowly in the environment. A total residue method was used in estimating the 

water concentrations in the eco risk assessment. This is because the main ring structures in the 

transformation products which were tentatively identified or characterized in the fate studies 

remain unchanged (almost the same as the parent compound). In the modeling, EFED assumed 

spinosad and its transformation products are stable under the aqueous photolysis, aerobic soil 

metabolism, and anaerobic aquatic metabolism conditions. In conclusion, spinosad residues are 

expected to be very stable in the aquatic environment. Below are the general fate properties for 

spinosad Factor A and Factor D. 

Spinosad Factors A and D converted in an aerobic soil metabolism study to transformation 

products very similar to the parent with half-lives of approximately 9-17 days. Similar 

transformation products are formed under photolytic conditions with a half-life of less than one 

day at pH 7 in sterile water and about 10 days in soil. The photodegradation half-life is assumed 

to be stable because the study was not conducted long enough to provide formation and decline 

information on the transformation products. Spinosad Factor A has a low to moderate water 

solubility and a low to slight mobility in sandy soils, and is immobile in silt loam and clay loam 

soils. Although no mobility data are available for Spinosad Factor D, it is 180x less soluble than 

Factor A and therefore would be expected to be less likely to leach in the soil. In terrestrial field 

dissipation studies with Spinosad Factor A on bareground plots, the half-life was <1 day, no 

leaching was observed, and 3.1% of the applied was recovered in runoff.
20

Spinosad has a high affinity for sediment and moves rapidly from the water to the sediment 

phases where it is highly persistent. In anaerobic aquatic metabolism studies, spinosad had a 

half-life of 161-250 days. In an aquatic microcosm dissipation outdoor study, spinosad residues 

in the sediment peaked at 8 days and had an observed half-life of >>25 days. Spinosad has a

relatively low bio-concentration factor (BCF’s of the parent 7.5X, 28.8X, and 21.1X for muscle, 

viscera, and whole fish, respectively), and a relatively rapid rate of depuration (half-life of about 

one day). These factors generally would prevent substantial bio-concentration of the material in 

the food web. 

Degradation and Metabolism

Spinosad Factors A and D were relatively stable in pH 5, 7, and 9 sterile aqueous buffer 

solutions that were incubated in the dark at 25°C. 

In sterile buffered (pH 7) solutions, spinosad Factors A and D phototransformed with half-lives

of 0.8-0.9 days. The β-isomers of the 13,14-dihydro of the pseudoaglycone of Factor A and of 

Factor D were detected at a maximum of 20.2-24.9% of the applied at 48 hours (study 

termination). In alkaline (pH 9.2) pond water, Factors A and D phototransformed rapidly with 

half-lives of 0.54-0.55 days. On soil, Factors A and D had photodegradation half-life of 8.68-

9.71 days. The only transformation present at >5 % of the applied was Factor B (N–

demethylated Factor A), which reached 14.8% of the applied at 18 days post-treatment. These 

studies were not long enough to determined the fate of the transformation products

In aerobic silt loam soil, Spinosad Factors A and D converted to transformation products with 

initial half-lives of 17.3 and 14.5 days, respectively. Factor A converted to transformation 

products with a half-life of 9.4 days in sandy loam soil incubated under similar conditions. 

Approximately 75-90% of the applied spinosad converted to transformation products by 28 days. 

The major degradate of Factor A was Factor B (N-demethylated Factor A), which accumulated 

to a maximum 51-61% of the applied at 14-28 days post-treatment, then decreased to 12.27-

21.72% at 9 months and 2.77-5.96% at 1 year. The major transformation product of Factor D 

was N-demethylated Factor D (the Factor D analogue of Factor B), which accumulated to a 

maximum 68% of the applied at 28 days post-treatment and approximately 50% at 6 months. 

Several minor transformation products, each <10% of the applied, were isolated but not 

conclusively identified.

In anaerobic flooded clay sediment, Factors A and D converted to transformation products with 

half-lives of 161 and 250 days. By 7 days post-treatment, >90% of the applied radioactivity was 

associated with the sediment fraction. Three major transformation products of Factor A, each 

present at a maximum 8-12% of the applied chemical, were identified: Factor B (N-demethylated 

Factor A), reversepseudoaglycone (806643), and ketoreversepseudoaglycone (814426). One 

major transformation products of Factor D, N-demethylated Factor D (the Factor D analogue of 

Factor B), was present at a maximum 6.5% of the applied. 

The fate of spinosad under the aerobic aquatic environment is unknown. This is because the 

submitted study (MRID 46642701) is classified as unacceptable and is scientifically invalid 

because significant variability in the results between sampling intervals and between systems at 
21

the same sampling interval prevents any confident interpretation of the study results. Because of 

poor results in the initial experiment, the data presented in this MRID are a compilation of 

analyses of selected test systems from four separate experimental sets for each test substance and 

system. In addition, transformation products comprising ≥10% of the applied may have been 

present and not identified.

Soil sorption and mobility

The mobility of Factor A, at nominal concentrations of 0.04-5.0 μg/mL, was investigated in 

sand, loamy sand, sandy loam, silt loam, and clay loam soils. Koc values were 2,862, 831, 4,237, 

134,583, and 21,938, respectively. Freundlich Kdes values for both desorption phases for the 

sand, loamy sand, sandy loam, and silt loam soils were 8.4-9.2, 6.6-8.2, 27-30, 288-357 and 292-

296, respectively; corresponding 1/n values ranged from 0.826-0.921. The reviewer-calculated 

coefficients of determination (r2) for the relationships Kads vs. organic matter, Kads vs. pH and 

Kads vs. clay content were 0.0647, 0.0498, and 0.8114, respectively.

The mobility of Factor B, the major degradate of Factor A, was investigated at 0.05-5.0 μg/mL 

in sand, loamy sand, sandy loam, and silt loam soils. Koc values were 2,138, 662, 2,881, and 

74,583, respectively. Freundlich Kdes values for both desorption phases for the sand, loamy sand, 

sandy loam, and silt loam soils were 6.3-6.5, 5.3-6.3, 19-20, and 171-179, respectively; 

corresponding 1/n values ranged from 0.775-0.880. The reviewer-calculated coefficients of 

determination (r2) for the relationships Kads vs. organic matter, Kads vs. pH and Kads vs. clay 

content were 0.425, 0.235 and 0.957, respectively.

Factors A and D are not volatile; vapor pressures (25°C) are 2.0 to 3.0 x 10-11 kPa. CO2 was the 

only volatile compound detected in metabolism studies.

Field dissipation

Factor A, formulated as an emulsifiable concentrate, degraded with half-lives of 0.5 days in 

bareground plots of silt loam soil in Mississippi and 0.3 days in loam soil in California. 

Approximately 2-3% remained after 3-5 days. No degradates were identified. Spinosad Factor 

A and its degradates were not detected below the 6-inch soil depth. Unextracted [14C] residues 

increased to a maximum of 34-58% by 38-40 days. At the Mississippi site, total radioactivity in 

the runoff accounted for 3.1% of the applied radioactivity. 

Pond water (pH 7.6, ca. surface area 2.2 m2, depth 47.5-50 cm) and clay loam sediment (ca. 

depth 5.5-6 cm) maintained in outdoor tanks were treated once with a broadcast-spray 

application of the suspension concentrate at 100 g/ha to the water surface. Spinosad (Factors A 

+ D) dissipated rapidly from the water with a calculated half-life of 1.5 days, and total spinosad 

residues dissipated from the water with a calculated half-life of 4 days. In the water, the 

degradates Factors B and B of D were detected at maximums of 2.3 ppb (8 hours) and 3.6 ppb (0 

hour), respectively, and were <0.5 ppb at 15 days. In the sediment, Factor A was detected at a 

maximum average 14.9 ppb at 4 days and was 14.3 ppb at 35 days. Factor B was detected at a 

maximum average 11.1 at 15 days and was ≤9.4 ppb at 35 days. Factors D was ≤4.2 ppb and B 

of D was not detected (LOD 11.3 ppb) at any interval in the sediment. Total spinosad residues in 
22

the water had an observed half-life of <1 days. Total spinosad residues in the sediment reached a 

maximum concentration at 8 days post-treatment and had decreased by approximately 25% by 

35 days. These field studies need to be re-evaluated because the half-lives may reflect the 

transformation of the parent to other transformation products similar to the parent. Also the 

dissipation half-lives reflect the movement of the parent and transformation products from one 

media to another and do not show degradation of the product.

Accumulation

[

14C]Factors A and D accumulated in rainbow trout held under laboratory flow-through 

conditions for up to 28 days. In the high concentration experiments (19.0 ng/L for Factor A and 

33.0 ng/L for Factor D), maximum BCFs for Factor A were 28.8 mL/g (at Day 28) for the 

nonedible tissue, 7.5 mL/g (at Day 25) for the edible tissue, and 21.1 mL/g (at Day 7) for the 

whole fish tissue; and for Factor D were 42 mL/g (at Day 11) for the nonedible tissue, 20.5 mL/g 

(at Day 11) for the edible tissue, and 41.9 mL/g (at Day 7) for the whole fish tissue. Registrantcalculated BCFs for total [14C]residues were 103-152, 16-47, and 84-115 mL/g for the nonedible, 

edible, and whole fish tissues, respectively. 

In fish exposed to Factor A, parent accounted for 68.34% of the HPLC distribution in whole fish 

extracts on exposure day 1, and ≤29.74% at later sampling intervals. Spinosad Factor J was 

present at 125 ng/g in day 25 nonedible extracts and day 28 whole fish extracts; all other 

degradates were each <50 ng/g. In fish exposed to Factor D, parent accounted for 83.43% of the 

HPLC distribution in whole fish tissue on exposure day 1, 48.80% on day 7, 42.19% on day 14, 

and 35.44% on day 28. In the whole fish tissues, 15-Pk4 and 20-Pk4 [N-monomethylated, Odemethylated Spinosad Factor D] was a maximum of 134 ng/g; 15-Pk6 and 20-Pk6 [Nmonomethylated, O-demethylated Spinosad Factor D] was a maximum of 230 ng/g; Spinosad 

Factor L was a maximum of 229 ng/g; Spinosad Factor O was a maximum of 173 ng/g; and 

Spinosad Factor B of D was a maximum of 544 ng/g. All other metabolites were <50 ng/g.

3.1 Aquatic Exposure Estimates

An aquatic exposure analysis was provided in previous risk assessments for spinosad use on turf

(DP279684+) and bulb onion and mint (DP310860+). The current risk assessment evaluated the 

EECs (total residues) based on the proposed uses (Table 7). PRZM/EXAMS output is given in 

Appendix D. The resulting EECs were less than or similar to the turf use but greater than the 

bulb onion and mint uses. Therefore, this assessment relies on the aquatic analyses performed in 

the previous assessments due to lower use rates in the bulb onion and mint assessment and 

similar or higher rates in the turf assessment.

Table 7. EECs for the proposed use of spinosad as a seed treatment.

PRIZM/EXAMS EECs for Spinosad Seed Treatment Use

Crop Portion

Application 

Rate 

lb a.i./A

Number of 

Application 

Acute 

Conc.

ppm

21 Day

Conc.

ppm

60 Day

Conc.

ppm
23

Onions 

for Seed

Water 

Column

0.45 1 0.004 0.004 0.004

Pore 

Water

0.45 1 0.004 0.004 0.004

3.2 Terrestrial Exposure Estimates

Consumption of spinosad-treated seed is the most likely exposure route for terrestrial animals. 

The Terrestrial Exposure Model (Version 1.4.1), was used to estimate the dietary exposure to 

terrestrial birds and mammals. Because of the differences in foliar application and seed 

treatment uses of pesticides, the seed treatment worksheet of TREX was used as a “stand-alone” 

tool for estimating the avian and mammalian exposure concentrations for various crops. 

The seed treatment worksheet of TREX assesses dietary exposure in two different ways. The 

first approach estimates the dietary dose assuming that an organism has been eating only treated 

seed. Using this assumption, the seed treatment worksheet calculates the food consumed by 

birds and mammals using Nagy’s allometric food consumption equations. Food consumption is 

calculated for the smallest avian (20-gram weight) and mammalian (15-gram weight) species 

(Appendix A). Using a scaling factor approach, which adjusts food intake and toxicity values to 

account for the differences in the size of the animal assessed compared with the size of the 

animal used in the toxicity tests, daily doses or Nagy doses are calculated. Avian and

mammalian Nagy doses for spinosad were calculated using the equation – (daily food intake 

g/day * 0.001 kg/g * maximum seed application rate mg/kg-seed) / body weight of animal (kg). 

The second method calculates the available concentration of pesticide on the basis of pesticide 

applied per square foot. Maximum spinosad application for each crop is converted to mg a.i./sq 

ft in order to derive an estimate of the pesticide exposure per square foot. 

Typical input values (for foliar treatments) for TREX include application rate, time interval 

between two applications, total number of applications and foliar half-life periods. Since 

spinosad is a seed-treatment insecticide, terrestrial EECs were derived using 1 application for the 

maximum proposed use rates for each crop. The default seeding rates contained in the TREX 

model were used when available for the various crops. When assessing the maximum 

application rate per acre, the default seeding rates provided in TREX were used for the following 

crops: onion - bulb vegetables (crop group 3), dried beans - dried shelled pea and bean (except 

soybean)(subgroup 6C)(excluding lentils, cowpea), field pea – leaves of legume vegetables 

(subgroup 7A) (excluding cowpea, lentils). Seeding rates for Seeding rates for watermelon, 

pumpkin, cantaloupe, and cucumber (cucurbits crop group 9; excluding cantaloupe, pumpkin, 

watermelon, and winter squash) were obtained from Granberry et al. 2008. Seeding rates for 

winter squash were obtained from Kemble et al., 2000. When the application rate per acre in 

TREX based on default seeding rates exceeded the maximum labeled seasonal amount, the 

seeding rates in TREX were adjusted to achieve the maximum labeled seasonal application rate. 

The TREX model assumes a default density of 8.33 lb/gal, and the spinosad label only indicates 

that the formulated product contains 80% active ingredient by weight. This density was 
24

therefore used in the TREX model. Also, as spinosad is a seed-treatment, foliar half-life periods 

are irrelevant for this analysis. 

4 Ecological Effects Assessment 

The short-term and long-term exposure effects of spinosad on terrestrial organisms were 

characterized based on the studies submitted by the registrant only as the ECOTOX database 

review did not reveal any open literature studies for spinosad that were relevant. Toxicity studies 

available for this risk-assessment and the measurement endpoints selected for each taxonomic 

group are included in Appendix C of this document. 

4.1 Aquatic Effects Summary

An aquatic effects analysis was provided in the previous risk assessments for spinosad on bulb 

onion and mint (DP310860+) as well as on turf (DP279684+). The current risk assessment relies 

on the aquatic analyses performed in these assessments.

4.2 Terrestrial Effects Summary

The registrant submitted eight studies to document spinosad’s effects on terrestrial birds and 

mammals. One study from the registrant examined the effects of spinosad on earthworms. At 

this time the Agency does not have an established method to assess risk to beneficial terrestrial 

invertebrates. Therefore this study can only be qualitatively to characterize risk from spinosad to 

terrestrial invertebrates.

4.2.1 Toxicity Effects on Terrestrial animals

Spinosad is categorized as slightly toxic to avian species on an acute oral basis (Table 8). Both 

the mallard duck and the bobwhite quail LD50's are >1333 mg/kg (MRIDs 434145-28 and 

434145-29). Spinosad is categorized as practically nontoxic to avian species on a subacute 

dietary basis. Both the mallard duck and the bobwhite quail LC50 are >5156 ppm (MRIDs 

434145-28 and 434145-29). Reproductive parameters (eggs laid, live 3-week embryos, normal 

hatchlings, 14 day-old survivors, etc.) were significantly reduced in both mallard ducks and 

bobwhite quail at 1100 ppm (MRIDs 434145-32 and 434145-33). The NOAEC for both species 

is 550 ppm.

Based on mammalian data in the Hazard Evaluation Division’s toxicity database, the rat acute 

oral LD50 is 3738 mg/kg, categorizing spinosad as practically non-toxic to small mammals. A 

reproductive study with rats identified a NOAEC of 10 mg/kg/day, based on reproductive 

toxicity (in young: reduced litter size, offspring body weights, and survival of F2 generation).

Developmental studies with rats and rabbits showed no evidence of toxicity. The NOAEC in the 

rat study (MRID 435575-05) was ≥4000 ppm or ≥200 mg/kg/day, the highest dose tested. The 

NOAEC in the rabbit study (MRID 434145-21) was ≥1000 ppm or ≥50 mg/kg/day.
25

Table 8. Toxic Effects in Terrestrial Animals Due to Acute and Chronic Exposure to 

Spinosad.

Selection of Terrestrial Toxicological Endpoints Used to Calculate Risk Quotients for Spinosad

Type Of 

Toxicity

Organism Species Toxicological 

Endpoint

MRID #

Oral Acute

 Bird

Bobwhite/Mallard LD50 >1333 mg/kg 434145-29/ 434145-

28

Dietary Bobwhite/Mallard LC50 >5156 ppm 434145-31/ 434145-

30

Chronic Bobwhite/Mallard NOAEC = 550 ppm 434145-33/ 434145-

32

Oral Acute

 Mammal

Rat LD50 3738 ppm 437707-01/434145-

15

Chronic Rat NOAEC >10 ppm 437015-06

4.2.2 Toxicity Effects on Invertebrates

Effects to terrestrial invertebrates are summarized below in Tables 9 and 10. Only one study has 

been submitted that examines the effects of spinosad on terrestrial invertebrates in the 

rhizosphere, which is based on effects to the earthworm. No toxicity was shown to earthworms 

in soil (based on reduction in biomass). The 14-day LC50 was >970 mg/kg (MRID 434145-48). 

However, the chemical is highly toxic to the honey bee.

Table 9. Toxic Effects in Terrestrial Invertebrates.

Non-target insect toxicity

Species

% ai Results Toxicity 

Category/effects

MRID

Study 

Classification

Honey bee

(Apis mellifera)

88% 0.0029ugai/b

ee

Highly Toxic 434145-47 Acceptable

Honey bee

(Apis mellifera)

0.02 N/A N/A 453408-01 Invalid

Honey bee

(Apis mellifera)

22.8% N/A N/A 450077-04 Invalid

Honey bee

(Apis mellifera)

24% RT 25 = 3hrs Mortality 450077-02 Supplemental

Honey bee

(Apis mellifera)

22.8% N/A N/A 450077-03 Invalid

Honey bee (residue)

(Apis mellifera)

23.5% RT 25 = 3hrs Mortality 450077-01 Acceptable
26

Honey bee (field 

trail)

(Apis mellifera)

GF-120 

Succes

s fruit 

fly

No adverse 

effects at use 

rates

N/A 457082-01/457088-01 Supplemental

Table 10. Toxic Effects in Terrestrial Invertebrates in the Rhizosphere Due to Acute

Exposure to Spinosad.

Earthworm Toxicity

Species % ai

LC50

(mg/kg)

NOAEC 

(mg/kg)

Endpoints 

Affected MRID Study 

Classification

*Earthworm 88 >970 970 weight 

decreases

434145-48 Supplemental

4.3 Incident Database Review

EPA maintains an incident database system called Ecological Incident Information System 

(EIIS), to track and evaluate accidental kills associated with pesticide use. Based on the 

information contained in the incident report, the likelihood of a particular pesticide causing the 

incident is listed as highly probable, probable, possible, or unlikely. If there are incident, this 

information will be reviewed and considered in conjunction with the degree to which the LOCs 

were exceeded, information on sales, local use practices, and monitored levels in the 

environment to determine whether the predicted effect based on labeled use of the product, is 

likely to occur or not. 

A review of the Ecological Incident Information System (EIIS), maintained by the Agency’s 

Office of Pesticide Programs (OPP) indicates several reported ecological incidents reported with 

the use of spinosad (Table 11). 

There were 4 incidents reported in the EIIS database. All incidents reported were plant related. 

No residue analysis was reported for any incidents.

Table 11. Ecological Incident Results as Listed by EIIS.

Incident # Date Crop State Certainty Legality Application Magnitude

IO13636-036 3.15.02 Orange CA 2 -possible RU Broadcast 21 acres

IO12366-001 9.10.01 Corn CA 2- possible UN UN 9000 acres

IO13550-002 6.22.01 Potato DE 2- possible RU Spray 65 acres

IO10927-029 4.15.00 Tobacco TN 1- unlikely RU Spray 45 acres

5 Risk Characterization

Risk characterization is the integration of exposure and effects to determine the ecological risk 

from the use of such stressors as spinosad. The risk characterization provides estimations and 
27

descriptions of the risk; articulates risk assessment assumptions, limitations, and uncertainties; 

synthesizes an overall conclusion; and provides the risk managers with information to make 

regulatory decisions. 

5.1 Risk Estimation

The risk quotient (RQ) method was used to provide a metric for potential adverse ecological 

risks from the proposed uses of spinosad. The risk quotient, a comparison of exposure estimates 

and toxicity endpoints, is estimated by dividing exposure concentrations by acute or chronic 

toxicity values (Appendix B). The resulting unitless RQs are compared to the Agency’s levels 

of concern (LOC) to determine the need for regulatory action.

These LOCs are criteria used by OPP to indicate potential risk to non-target organisms and the 

need to consider regulatory action. The criteria indicate that a pesticide used as directed has the 

potential to cause adverse effects on non-target organisms. LOCs currently address the 

following risk presumption categories: (1) acute – potential for acute risk is high, regulatory 

action may be warranted in addition to restricted use classification (2) acute restricted use -

potential for acute risk is high, but this may be mitigated through restricted use classification (3) 

acute endangered species – the potential for acute risk to endangered species is high, regulatory 

action may be warranted, and (4) chronic risk - the potential for chronic risk high, regulatory 

action may be warranted. Currently, EFED does not perform assessment for chronic risk to 

plants, acute or chronic risks to non-target insects or chronic risks from granular/bait 

formulations to mammalian or avian species. 

The ecotoxicity test values (i.e., measurement endpoints) used in the acute and chronic risk 

quotients are derived from the results of required studies. Examples of ecotoxicity values 

derived from results of short-term laboratory studies that assess acute effects are (1) LC50 (fish 

and birds), (2) LD50 (birds and mammals), (3) EC50 (aquatic plants and aquatic invertebrates, and 

(4) EC25 (terrestrial plants). An example of a toxicity test effect level derived from the results of 

a long-term laboratory study that assesses chronic effects is (1) NOAEC (birds, fish, and aquatic 

invertebrates). Risk presumptions, along with corresponding RQs and LOCs are tabulated in 

Appendix B. 

5.1.1 Summary of Aquatic Risk Quotients

An aquatic assessment was provided in previous risk assessments for spinosad (DP310860+ and 

DP279684+). The current risk assessment relies on the aquatic analyses performed in these

assessments.

5.1.2 Summary of Terrestrial Risk Quotients

Table 12 summarizes the acute and chronic avian and mammalian RQs. Due to the lack of a 

definitive LD50 for both mammalian and avian acute toxicity, all of the acute RQs are less than 

the number reported. The acute RQs ranged from <0.02 to <23.24 for birds (20-gram weight) 

and 0.00 to 4.25 for mammals (15-gram weight), where many of the uses exceeded the 

endangered species LOC of 0.1. 
28

Table 12. Summary of Terrestrial Acute and Chronic Risk Quotients. Values in bold 

represent an exceedence of the respective LOC.

Crop

Acute Dose-Based RQs Chronic RQs3

Avian RQs Mammalian RQs Avian RQs Mammalian RQs RQ11 RQ22 RQ11 RQ22

Onion: Bulb 

vegetables <23.244 <0.245 2.274 0.04 160.36 441.00

Watermelon <4.354 <0.02 0.435 0.00 30.00 82.50

Pumpkin <3.274 <0.02 0.325 0.00 22.55 62.00

Winter 

Squash <2.194 <0.02 0.215 0.00 15.09 41.50

Cantaloupe <9.144 <0.04 0.895 0.01 63.09 173.50

Cucumber:

Cucurbit 

vegetables 

(crop group 

9; excluding 

cantaloupe, 

pumpkin, 

watermelon, 

winter 

squash)

<9.944 <0.06 0.974 0.01 68.55 188.50

Dried bean

and shelled 

pea 

<0.534 <0.07 0.05 0.01 3.64 10.00

Field pea:

Leaves of 

legume 

vegetables

(subgroup

7A)

(excluding 

cowpea, 

lentils)

<2.484 <0.565 0.245 0.09 17.09 47.00

1

Acute RQs for birds and mammals are determined by dividing the estimated dietary intakes 

(mg/kg-bw/day) by a body weight adjusted avian LD50 of 1333 mg/kg-bw for Bobwhite quail

and a body weight adjusted mammalian LD50 of 2000 mg/kg-bw for the rat. 

2

Acute RQs were based on pesticide applied per square foot (mg a.i./ft2/LD50*bw)

3

Chronic RQs were based on spinosad seed application rate (mg a.i./kg seed) divided by a 

dietary-based NOAEC (550 mg/kg-diet for the mallard duck and a 200 mg/kg-diet for the rat).

4

RQ exceeds the LOCs of 0.5 and 0.1 for non-listed and listed species, respectively.

5

RQ exceeds the LOC of 0.1 for listed species.

An analysis of the results shows that the acute avian RQs exceeded the listed and non-listed 

species LOC for the proposed use of spinosad on a dose basis (RQ1) for every crop use. Acute 

mammalian RQs also exceeded the listed species LOC on a dose basis (RQ1) for all of the uses
29

except for dried bean and shelled pea and the non-listed species LOC for the following crops: 

bulb vegetables (crop group 3), cantaloupe, and cucurbits (crop group 9, as listed in Table 12). 

Avian chronic RQs exceeded the LOC for every crop group. Mammalian chronic RQs exceeded 

the LOC for every crop group as well.

Currently, EFED does not assess risk to non-target insects. Results of acceptable studies are 

used for recommending appropriate label precautions. The study results show that spinosad is 

highly toxic to honeybees, but shows low toxicity to earthworms. 

5.2 Risk Description

The results of this baseline risk assessment indicate that the proposed uses for spinosad pose risk

to both non-listed and listed mammalian and avian taxa. Therefore, the hypothesis that spinosad

has the potential to compromise survival and cause sub-lethal effects in non-target species is 

supported.

5.2.1 Risk to Aquatic Organisms

An aquatic effects analysis was provided in the previous risk assessments for spinosad on bulb 

onion and mint (DP310860+) as well as on turf (DP279684+). The current risk assessment relies 

on the aquatic analyses performed in these assessments. The aquatic EEC’s in this assessment

were similar to or lower than the previous assessment for turf (DP279684+), but higher than 

those for mint and green onion (DP310860+). In both assessments, chronic risk was found for 

freshwater free-swimming and benthic sediment dwelling invertebrates, but no risk was found 

for aquatic plants. Therefore, the proposed spinosad seed treatment would also pose risk to these 

freshwater animals and not to aquatic plants. 

5.2.2 Risk to Terrestrial Organisms

Many of the crop uses pose acute and chronic risk to small birds and mammals (Table 12). 

Based on the application rate per acre per season (RQ2), there are no bird or mammal acute risks 

that appear for non-listed species. However, there is acute risk based on this method (RQ2) to 

listed birds for the following uses: bulb vegetables (crop group 3) and leaves of legume 

vegetables (subgroup 7A; excluding cowpea, lentils). There is no acute risk to any listed or nonlisted mammal species, however, based on the RQ2 method. The risk picture is very different 

based on the application rate per seed (RQ1). There is acute risk to both listed and non-listed 

birds for every use. There is also acute risk to listed mammals for all of the crop uses except for 

dried bean and shelled pea, and acute risk to non-listed mammals for the following crop uses: 

bulb vegetables (crop group 3), cantaloupe, and cucurbits (crop group 9, as listed in Table 12). 

Similarly, the proposed applications for every crop use pose a chronic risk concern to avian and 

mammalian wildlife.

The differences between the RQs based on an area basis (RQ2, LD50/ft2

) versus the oral dose

(RQ1, ingestion of seeds) suggest that the application rate per seed drives most of the risk 

conclusions for this assessment. For example, the maximum application rate in lbs a.i. per 100 

lbs of seed is 8.8 lbs for bulb onions. This rate is high enough to trigger an acute and chronic

risk concern for non-listed and listed birds and mammals. Yet the risk based on application rate 

per acre results in only acute risk to listed species. The amount of a.i. per seed appears to be 

triggering most of the acute and chronic concern for risk, at least for non-listed species. Note 
30

however, that three of the uses pose a risk concern to listed avian species, even based on the 

application rate per acre. This suggests that enough a.i. could be applied to a field at the 

maximum application rate per acre to pose a risk to endangered and threatened birds, so slightly 

lower application rates per acre would reduce the risk to these taxa. However, the maximum 

application rate for most of the crops per seed would need to be substantially reduced to 

eliminate acute risk to listed and non-listed birds and mammals.

The non-definitive endpoints derived from the acute toxicity studies to birds affect the risk 

conclusions in this assessment. Though this risk assessment shows that acute risk is present for 

both birds and mammals based on the application rate per seed, the avian acute RQ’s are 

undefined and there is uncertainty regarding this risk due to the lack of definitive endpoints. For 

some crop uses, the lack of effects in the acute studies means that the presumed risk is low. 

However, for bulb vegetables (crop group 3), foliage of legume vegetables (excluding soybean) 

(subgroup 7A), cantaloupe, cucurbit vegetables (crop group 9), pumpkin, winter squash, and 

watermelon, the EECs are greater than the highest dose tested in the acute toxicity studies for 

avian wildlife. The hazard of the chemical has not been evaluated at exposure levels above the 

highest dose tested in the acute toxicity studies. Therefore, while risk may be considered low for

those uses that result in EECs less than the highest dose tested in the toxicity studies, risk cannot 

be precluded for these other uses, considering that mortality was found in the acute avian study 

with Bobwhite quail. Based on the results of TREX, the maximum application rate per seed 

would need to be ≤ 0.38 lbs a.i./cwt to eliminate this uncertainty for birds.

TREX evaluates chronic risk based on the feeding rates of birds and mammals and incorporates 

the amount of a.i. per seed to establish exposure. For both birds and mammals, definitive 

NOAEC values have been derived from studies submitted by the registrant. All of the uses pose 

a chronic risk to birds and mammals. The application rate per seed drives this risk conclusion 

and suggests that alternative rates could be explored to reduce the level of risk to birds and 

mammals on a chronic basis. 

It is highly likely that the spinosad use period in the United States will coincide with the time 

when birds and mammals seek crop fields in which spinosad-treated seeds are planted for food 

and cover. The peak usage period could also overlap with the reproductive cycles of birds and 

mammals. Typically, peak spinosad-seed treatment use would occur around planting time. 

Depending on the crop and the state in which it is planted, the planting time could span the entire 

year. 

The current assessment assumes that spinosad-treated seed represents 100% of the dietary needs 

for birds and mammals. In reality, birds and mammals may not feed on spinosad-treated seed for 

extended periods of time. While this assumption is conservative, the registrant submitted data 

are derived from a limited number of species that is then extrapolated to all mammalian and 

avian species. This extrapolation has uncertainty associated with it due to differences in species 

sensitivity. So at this screening level, the assumption of 100% of dietary needs being met 

through spinosad treated seed is used to be protective of all avian and mammalian species, and 

those species for which birds serve as a surrogate.

In summary, acute risk to listed and non-listed birds cannot be precluded for bulb vegetables 

(crop group 3), foliage of legume vegetables (excluding soybean) (subgroup 7A), cantaloupe, 
31

cucurbit vegetables (crop group 9), pumpkin, winter squash, and watermelon. Acute risk to nonlisted mammals was found for bulb vegetables (crop group 3), cantaloupe, and cucurbit 

vegetables (crop group 9; excluding pumpkin, watermelon, winter squash), while acute risk to 

listed mammals was found for all uses except dried bean and shelled pea. All of the proposed 

uses pose chronic risk to both birds and mammals. Based on previous assessments, chronic risk 

was found for freshwater free-swimming and benthic sediment dwelling invertebrates, but no 

risk was found for aquatic plants. Therefore, the proposed spinosad seed treatment would also 

pose risk to these freshwater animals and not to aquatic plants. No risk is present for terrestrial 

plants due to the low toxicity of spinosad to these organisms.

5.3 Endangered Species Assessment 

For the purposes of this screening level assessment listed plants and wildlife are assumed to be 

located on or adjacent to the treated field and aquatic organisms are assumed to be located in a 

surface water body adjacent to the treated field. This places the listed species within an assumed 

area of high potential exposure to the chemical.

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

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

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

situations where the screening assumptions lead to RQs in excess of the listed species LOCs for a 

given taxonomic group, there exists a potential for a “may affect,” conclusion that may be 

associated with direct effects on listed species or may extend to indirect effects upon listed 

species that depend on that taxonomic group as a resource. 

Avian and mammalian acute RQs exceeded the acute endangered species LOC 0.1. The chronic 

LOC was also exceeded for birds and mammals. These taxa therefore are at risk for direct 

effects under acute and chronic exposure to spinosad. 

To determine whether spinosad use sites are geographically associated with known locations of 

endangered species, a baseline level search of LOCATES (version 2.10.4) database was 

conducted. The database uses location information for endangered species at the state and 

county level and compares it to 2002 agricultural census data for crop production at the same 

level of resolution. Preliminary LOCATES analysis indicated that the proposed new use patterns 

for spinosad could potentially overlap with areas frequented by endangered avian and 

mammalian wildlife. Appendix E lists the species on which indirect effects could potentially 

occur due to new uses of spinosad. 

5.3.1 Probit Slope Analysis

The probit slope response relationship is evaluated to calculate the chance of an individual event 

corresponding to the listed species acute LOCs. If information is unavailable to estimate a slope 

for a particular study, a default slope assumption of 4.5 is used as per original Agency 

assumptions of a typical slope cited in Urban and Cook (1986). 

A. Terrestrial Species
32

Data from avian and mammalian terrestrial acute toxicity studies for spinosad did not provide an 

estimate of slope. 

5.3.2 Direct and Indirect Effects

Based on acute and chronic exceedances for birds and mammals, potential does exist for direct 

toxic effects to these endangered and threatened species, if exposure occurs. Given the potential 

direct effects of spinosad on birds and mammals (Table 13), indirect effects to animals (e.g. 

terrestrial phase amphibians, larger mammals) that rely on them for resources critical to their life 

cycle is possible. For example, non-listed and listed animals such as foxes, coyotes, and hawks 

feed on small animals such as mice, rabbits, and other rodents. Terrestrial phase amphibians 

such as salamanders depend on mice and other small mammals for food. Predators that feed on 

birds may also be affected by food chain transfer. Overall, reduced food/prey availability could 

result if reductions in populations of small mammals or bird populations occur due to acute and 

chronic exposure to spinosad. Potential chronic impacts on birds could also lead to reduced plant 

pollination and dispersal. If that were to happen, the effects of spinosad may cascade through the 

entire food web affecting several taxa. 

Table 13. Listed Species Risks Associated with the Proposed New Uses of Spinosad.

Listed Taxa Potential Direct Effects Potential Indirect Effects

Terrestrial and semi-aquatic 

plants – monocots No Yes

Terrestrial and semi-aquatic 

plants – dicots No Yes

Insects* Yes No

Birds Yes Yes

Terrestrial phase amphibians Yes Yes

Reptiles Yes Yes

Mammals Yes Yes

Aquatic phase amphibians No No

Aquatic plants No No

Freshwater fish No No

Freshwater crustaceans No No

Mollusks No No

Marine/estuarine fish No No

Marine/estuarine crustaceans No No

*Aquatic invertebrates only

5.4 Endocrine Disruption

As required under FFDCA section 408(p), EPA has developed the Endocrine Disruptor 

Screening Program (EDSP) to determine whether certain substances (including pesticide active 

and other ingredients) may have an effect in humans or wildlife similar to an effect produced by 

a “naturally occurring estrogen, or other such endocrine effects as the Administrator may 
33

designate.” The EDSP employs a two-tiered approach to making the statutorily required 

determinations. Tier 1 consists of a battery of 11 screening assays to identify the potential of a 

chemical substance to interact with the estrogen, androgen, or thyroid (E, A, or T) hormonal 

systems. Chemicals that go through Tier 1 screening and are found to have the potential to 

interact with E, A, or T hormonal systems will proceed to the next stage of the EDSP where EPA 

will determine which, if any, of the Tier 2 tests are necessary based on the available data. Tier 2 

testing is designed to identify any adverse endocrine related effects caused by the substance, and 

establish a dose-response relationship between the dose and the E, A, or T effect.

Between October 2009 and February 2010, EPA issued test orders/data call-ins for the first 

group of 67 chemicals, which contains 58 pesticide active ingredients and 9 inert ingredients. 

This list of chemicals was selected based on the potential for human exposure through pathways 

such as food and water, residential activity, and certain post-application agricultural scenarios. 

This list should not be construed as a list of known or likely endocrine disruptors.

Possible endocrine mediated effects were found in a chronic freshwater invertebrate study with 

Daphnia magna, where a NOAEC of 0.62 ppb was established based on a statistically significant 

reduction in egg production at the highest concentration tested (2.19 ppb). Egg production is an 

endocrine-mediated process. Also, there were increases in thyroid weights as well as increased 

thyroid, parathyroid and pituitary gland cell vacuolation in mammalian studies.

Spinosad is not among the group of 58 pesticide active ingredients on the initial list to be 

screened under the EDSP. Under FFDCA sec. 408(p) the Agency must screen all pesticide 

chemicals. Accordingly, EPA anticipates issuing future EDSP test orders/data call-ins for all 

pesticide active ingredients. 

For further information on the status of the EDSP, the policies and procedures, the list of 67 

chemicals, the test guidelines and the Tier 1 screening battery, please visit: 

http://www.epa.gov/endo/ .

5.5 Uncertainties

5.5.1 Exposure and Effects Assessment

- Variability in Species Sensitivity: Although the screening risk assessment relies on a 

selected toxicity endpoint from the most sensitive species tested, it does not necessarily 

mean that the selected toxicity endpoints reflect sensitivity of the most sensitive species 

existing in a given environment. The relative position of the most sensitive species tested in 

the distribution of all possible species is a function of overall variability among species to a 

particular chemical. For terrestrial animals, uncertainty associated with the limited 

quantification of interspecies variability in sensitivity to spinosad would probably not impact 

the risk assessment result substantially, given that spinosad is practically non-toxic to 

slightly toxic to terrestrial animals. 

- Effects of Pesticide Mixtures: This assessment considered only exposure to the active 

ingredient spinosad. However, simultaneous exposures to multiple chemical and physical 

stressors are likely to occur in the environment. No acceptable data was found that 
34

evaluated potential additive, synergistic, or antagonistic interactions between spinosad and 

other chemical stressors. If such interactions occur, then risks could be under or overestimated. 

- Acute Toxicity for Birds: For bulb vegetables (crop group 3), foliage of legume vegetables 

(excluding soybean) (subgroup 7A), cantaloupe, cucurbit vegetables (crop group 9), 

pumpkin, winter squash, and watermelon, the EECs are greater than the highest dose tested 

in the acute toxicity studies for avian wildlife. The hazard of the chemical has not been 

evaluated at exposure levels above the highest dose tested in the acute toxicity studies,

which represents an uncertainty given the mortality found in the Bobwhite quail acute oral 

toxicity study.

- Data Gaps: The data gaps that were outlined in Section 2.6.1 were either required or 

conditionally required for spinosad and still have to be submitted. Acceptable data from 

these studies will aid in reducing some of the uncertainty associated with this assessment. 

6 Bibliography

Granberry, D.M., T. Kelly, G. Boyhan. 2008. Seeding Rates for Vegetable Crops. University of 

Georgia Cooperative Extension. Bulletin 1128. Accessed from 

http://www.caes.uga.edu/publications/pubDetail.cfm?pk_id=6961

Kemble, J.M., E.J. Sikora, G.W. Zehnder, E. Bauske. 2000. Guide to Commercial Pumpkin and 

Winter Squash Production. Alabama Cooperative Extension System. ANR-1041. Accessed from

http://www.aces.edu/pubs/docs/A/ANR-1041/ANR-1041.pdf

Nagy, K. A. 1987. Field metabolic rate and food requirement scaling in mammals and birds. 

Ecological Monographs. 57:111-128.

U.S. Environmental Protection Agency. 1998. Guidelines for Ecological Risk 

Assessment. Risk Assessment Forum, Office of Research and Development, 

Washington, D.C. EPA/630/R-95/002F. April 1998. 

U.S. Environmental Protection Agency. 2004. Overview of the Ecological Risk 

Assessment Process in the Office of Pesticide Programs, U.S. Environmental Protection 

Agency. Endangered and Threatened Species Effects Determinations. Office of 

Prevention, Pesticides and Toxic Substances, Office of Pesticide Programs, Washington,

D.C. January 23, 2004.

U.S. Environmental Protection Agency. 2005. Generic Format and Guidance for the 

Level I Screening Ecological Risk Assessments Conducted in the Environmental Fate 

and Effects Division. Office of Pesticide Programs, Washington, D.C. January 24, 2005. 

U.S. Environmental Protection Agency. 2004. Overview of the Ecological Risk Assessment 

Process in the Office of Pesticide Programs. http://www.epa.gov/oppfead1/ 
35

endanger/consultation/ecorisk-overview.pdf

USDA-NASS. Multiple years. Crop Production. Accessed from http://www.nass.usda. gov 

/Statistics_by_Subject/index.asp
36

Appendix A. TREX Methodology to Calculated Nagy Doses (EECs) 

and Risk Quotients for Birds and Mammals

The seed treatment worksheet of TREX calculates the avian and mammalian doses or exposure 

concentrations using two approaches: Nagy doses (mg a.i./kg-bw day-1) and pesticide available 

on unit soil surface area (mg a.i. ft2

). Nagy doses are used in the calculation of both acute and 

chronic RQs for birds and mammals. Only acute RQs are calculated using the pesticide available 

on unit soil area.

Nagy doses for seed treatment applications are calculated using the scaling factor approach for a 

20-gram bird and 15-gram mammal. The scaling factor approach adjusts the food intake and 

toxicity values to account for the differences in the size of the animal assessed compared with the 

size of the animal used in the toxicity tests. The Agency calculates the avian and mammalian 

Nagy doses using the equation below:

Avian and Mammalian Nagy Doses (mg a.i./kg-bw) = (daily food intake g/day *0.001 kg/g * 

maximum seed application (mg/kg-seed) / (body weight of animal (kg)

In the second approach, the amount of pesticide available on unit soil surface area is calculated 

by converting the maximum application rate from lb acre-1 to mg a.i./ft2. The equation used for 

this calculation is presented below:

Available a.i.(mg a.i./ft2) = (Maximum application rate (lbs/Acre) * 106 mg/kg) / (43,560 square 

feet/acre * 2.2 lb/kg)

Calculation of Risk Quotients (RQs) for Seed Treatment Applications

Acute risk quotients are calculated using the adjusted LD50 value for the smallest weight class of 

animal (20g for birds and 15g for mammals). Acute RQs are calculated using the two methods:

Method 1 or EEC/LD50 method

Acute RQ = mg a.i./kg-1 day-1/adjusted LD50

Method 2 or EEC/LD50 ft-2 method

Acute RQ = mg/kg-1 a.i. ft2 / (adjusted LD50 * body weight (kg)

Chronic RQs, which are not adjusted to different weight classes of birds or mammals, are 

calculated using the following equation:

Chronic RQ = mg a.i. kg-1 seed / NOAEC (mg/kg-diet)
37

Appendix B. The Risk Quotient Method and Levels of Concern

The Risk Quotient Method is the means by which the Environmental Fate and Effects Division (EFED) 

integrates the results of exposure and ecotoxicity data. In this method, both acute and chronic risk 

quotients (RQs) are calculated by dividing exposure estimates by the most sensitive ecotoxicity values or 

toxicity endpoints derived from the studies. Calculated RQs are then compared to OPP's levels of concern 

(LOCs). The LOCs are the criteria used by OPP to indicate potential risk to non-target organisms and the 

need to consider regulatory action. EFED has defined LOCs for acute risk, potential restricted use, and for 

endangered species. Risk presumptions, along with the corresponding RQs and LOCs are summarized in 

the table below.

Risk Presumption RQ LOC

Birds

Acute Risk EEC/LC50 or LD50/sqft or LD50/day 0.5

Acute Restricted Use EEC/LC50 or LD50/sqft or LD50/day (or LD50 < 

50 mg/kg)

0.2

Acute Endangered Species EEC/LC50 or LD50/sqft or LD50/day 0.1

Chronic Risk EEC/NOAEC 1

Mammals

Acute Risk EEC/LC50 or LD50/sqft or LD50/day 0.5

Acute Restricted Use EEC/LC50 or LD50/sqft or LD50/day (or LD50 < 

50 mg/kg)

0.2

Acute Endangered Species EEC/LC50 or LD50/sqft or LD50/day 0.1

Chronic Risk EEC/NOAEC 1

Aquatic Animals

Acute Risk EEC/LC50 or EC50 0.5

Acute Restricted Use EEC/LC50 or EC50 0.1

Acute Endangered Species EEC/LC50 or EC50 0.05

Chronic Risk EEC/NOAEC 1

Terrestrial and Semi-Aquatic Plants 

Acute Risk EEC/EC25 1

Acute Endangered Species EEC/EC05 or NOAEC 1

Aquatic Plants

Acute Risk EEC/EC50 1

Acute Endangered Species EEC/EC05 or NOAEC 1
38

Appendix C. Ecological Effects Data

Summary:

This insecticide was practically non-toxic to avian species-(subacutely) and mammals (acutely 

and chronically). However, Spinosad was slightly toxic to avian species-(acutely), cold-water 

fish, and freshwater aquatic invertebrates. Spinosad was moderately toxic to warm-water fish, 

estuarine/marine fish(acutely) and estuarine shrimp. Furthermore, this insecticide was found to 

be highly toxic to estuarine/marine oysters and honey bees(acute studies)

Toxicity to Terrestrial Animals

The results of acute/subacute toxicity testing indicate that Spinosad is practically nontoxic to 

avian species on a subacute dietary basis and slightly toxic on an acute oral basis. Results of 

avian toxicity testing with spinosad are tabulated below.

Avian Acute/Subacute Toxicity

 

Species

 % 

ai

LC50 (ppm)/ 

LD50 (ppm)

 

Toxicity Category

MRID No.

Author/Year

 

Study Classification

Northern bobwhite quail 

(Colinus virginianus)

88 LD50 >1333 slightly toxic 43414529

A.G. Murray 

et al (1992)

Supplemental1

Mallard duck

(Anas platyrhynchus)

88 LD50 >1333 slightly toxic 43414528

A.G. Murray 

et al (1992)

Supplemental1

Northern bobwhite quail 

(Colinus virginianus)

88 LC50 >5156 practically non-toxic 43414531

A.G. Murray 

et al (1992)

Core

Mallard duck

(Anas platyrhynchus)

88 LC50 >5156 practically non-toxic 43414530

A.G. Murray 

et al (1992)

Core

1 Study is classified supplemental, but does not need to be repeated (refer to Data Evaluation for details). Study is adequate for risk assessment 

purposes. 

 

Avian Reproduction

Species % ai

NOAEC/LOAEC 

(ppm) Endpoints Affected

MRID No.

Author/Year

Study 

Classification

Northern bobwhite quail

(Colinus virginianus)

88 550/1100 eggs laid, live 3-wk 

embryos, normal 

hatchlings, 14-day old 

survivors, hatchling 

weight 

43414533

J. B. Beavers et al

(1994) 

Core 

Mallard duck

(Anas platyrhynchus)

88 550/1100 eggs laid, eggshell 

thickness, viable 

embryos, live 3-wk 

embryos, normal 

hatchlings, 14-day old 

survivors, terminal 

female body weight

43414532

J. B. Beavers et al

(1994)

Core
39

Mammals, Acute and Chronic

Wild mammal testing is required on a case-by-case basis, depending on the results of lower tier 

laboratory mammalian studies, intended use pattern and pertinent environmental fate 

characteristics. In most cases, rat or mouse toxicity values obtained from the Agency's Health 

Effects Division (HED) substitute for wild mammal testing. Based on a laboratory rat LD50

value of >5000 mg/kg, spinosad is practically nontoxic to small mammals on an acute oral basis. 

These toxicity values are reported below.

Mammalian acute toxicity

Species % ai Test Type 

Toxicity

Value

Affected

Endpoints MRID 

Rat

(Rattus norvegicus)

Tech oral LD50 3738 mg/kg Male mortality 437707-01

434145-15

Mammalian chronic toxicity

Species % ai Test Type 

Toxicity

Value

Affected

Endpoints MRID 

Laboratory rat

(Rattus norvegicus)

88 Rat Reproduction 10 mg/kg-bw None 437015-06

Terrestrial Invertebrates

Earthworm Toxicity

Species % ai

LC50

(mg/kg)

NOAEC 

(mg/kg)

Endpoints 

Affected MRID Study 

Classification

Earthworm 88 >970 970 weight 

decreases

434145-48 Supplemental

Insects

Based on a honey bee acute contact test LD50 of 0.0029 ug ai/bee, Spinosad is highly toxic to 

bees on an acute contact basis (43414547; K.A. Hoxter et al 1992). The results of spinosad 

testing using the honeybee are tabulated below:

Non-target insect toxicity

Species

% ai Results Toxicity Category/effects MRID

Study 

Classification

Honey bee

(Apis mellifera)

88% 0.0029ugai/bee Highly Toxic 434145-47 Core

Honey bee

(Apis mellifera)

0.02 N/A N/A 453408-01 Invalid

Honey bee

(Apis mellifera)

22.8% N/A N/A 450077-04 Invalid

Honey bee

(Apis mellifera)

24% RT 25 = 3hrs Mortality 450077-02 Supplemental

Honey bee

(Apis mellifera)

22.8% N/A N/A 450077-03 Invalid

Honey bee (residue)

(Apis mellifera)

23.5% RT 25 = 3hrs Mortality 450077-01 Core

Honey bee (field trail)

(Apis mellifera)

GF-120 

Success 

fruit fly

No adverse 

effects at use 

rates

N/A 457082-01/457088-01 Supplemental
40

Toxicity to Aquatic Animals

The results of acute testing show that Spinosad is categorized as slightly toxic to cold-water 

freshwater fish and freshwater invertebrates, and moderately toxic to warm-water freshwater 

fish. Results of freshwater animal acute toxicity testing are tabulated below.

Freshwater Animal Acute Toxicity

Species % ai

EC50/

LC50 (ppm) Toxicity Category

MRID No.

Author/Year

Study 

Classification

Waterflea

(Daphnia magna)

88 EC50= 14

Slope=N/A

slightly toxic 434145-37

D.P. Milazzo et al

(1994)

Core

Waterflea

(Daphnia magna)

100 Factor D 

Static

66.8 Slightly toxic 465053-04 Acceptable

Waterflea

(Daphnia magna)

96 Factor D 

static

3.8

Slope=1.62

moderately toxic 465053-09 Acceptable

Waterflea

(Daphnia magna)

99 Factor A >197 practically non-toxic 465053-07 Acceptable

Waterflea

(Daphnia magna)

94 Factor B 6.5 moderately toxic 465053-12 Acceptable

Waterflea

(Daphnia magna)

94 Factor B 6.39/21.4

Slope=1.78

moderately toxic 445977-31 Supplemental

Rainbow trout

(Oncorhynchus mykiss)

88 LC50= 30 

Slope=4.39

slightly toxic 434441-03

J.T. Weinberg et al

(1993)

Core

Bluegill sunfish 

(Lepomis macrochirus)

88 LC50= 5.94

Slope=N/A

moderately toxic 434145-34

J.L. Newsted and 

D.E. Brock (1992)

Core

Based on results above, technical Spinosad and its metabolites are considered slightly to 

moderately toxic to freshwater aquatic invertebrates on an acute toxicity basis. Studies with 

Spinosad Factors resulted in limited solubility.

Technical Spinosad impacted reproduction in fish at 0.49 ppm and in invertebrates at the 0.0006 

ppm. The results of freshwater fish and invertebrate chronic testing are tabulated below.

Freshwater Aquatic Invertebrate Life-Cycle Toxicity and Fish Early Life-Stage Toxicity

Species % ai

NOAEC/LOAEC 

(ppm)

MATC 

(ppm)

Endpoints 

Affected MRID No.

Study 

Classification

Waterflea

(Daphnia magna)

88 0.0006/0.0012 0.0008 growth and 

reproductive

capacity

43848801 Core

Waterflea

(Daphnia magna)

96 Factor D

Flow-through

1.0/1.7 ppb survival, 

reproduction 

and growth

465053-01 Invalid

Waterflea

(Daphnia magna)

100 Factor D

Static renewal

4.85/9.32 length 465053-03 Supplemental

Waterflea

(Daphnia magna)

99 Factor A 1.59/3.24 (21 da) length 465053-06 Supplemental

Waterflea

(Daphnia magna)

93 Factor B

Flow-through

0.95/2.1 ppb survival/growth 465053-11 Invalid
41

Freshwater Aquatic Invertebrate Life-Cycle Toxicity and Fish Early Life-Stage Toxicity

Species % ai

NOAEC/LOAEC 

(ppm)

MATC 

(ppm)

Endpoints 

Affected MRID No.

Study 

Classification

Midge (Chironomus 

riparius)

Factor A & D 0.622/1.328 ppb 0.909 

ppb

% emergence 448284-02 Supplemental

Midge (Chironomus 

riparius)

Dihydropsuedoaglycon

e of Spinosad 99%

0.252/>0.252

0.0734/>0.0734

(28 da)

% emergence,

M & F 

developmental 

rates

465053-14 Supplemental

Rainbow trout 

(Oncorhynchus 

mykiss)

Factor A & D

Flow-through

1.2/2.1(21 da)

LC50=4.9

Signs of 

toxicity

mortality

465053-13 Supplemental

Rainbow trout 

(Oncorhynchus 

mykiss)

88 0.498/0.962 0.692 growth, 

survival, day to 

mean hatch

434145-41

J.T. Weinberg 

et al (1993)

Core

The results show that Spinosad is categorized as moderately toxic to estuarine/marine fish and 

moderately to very highly toxic to estuarine/marine invertebrates on an acute basis. The results 

of acute toxicity testing with estuarine/marine species are tabulated below.

Estuarine/Marine Acute Toxicity

Species % ai. LC50/EC50 (ppm) Toxicity Category

MRID No.

Author/Year

Study 

Classification

Sheepshead minnow

(Cypridon variegatus)

87.9 LC50 =7.87

Slope=7.62

moderately toxic 434145-40 Core

Eastern oyster (shell 

deposition or embryo-larvae)

(Crassostrea virginica)

87.9 EC50 = 0.3

Slope=2.2

very highly toxic 434441-04/435712-03 Core

Grass Shrimp (Palaemonetes 

pugio)

87.9 LC50>9.76

Slope=N/A

moderately toxic 434145-39 Supplemental

Mysid 

(Americamysis bahia)

87.9 LC50 >7.87 moderately toxic 434145-39 Supplemental1

1 Although the mysid shrimp study was classified as supplemental (organisms should have been fed during the study), the study does not have to 

be repeated because the oyster was found to be the most sensitive invertebrate species tested, and will be used for risk assessment purposes in lieu 

of the mysid shrimp.

 

Spinosad reduced growth of sheepshead minnow with a MATC of 1.65 ppm. Reproduction is 

impacted at concentrations as low as 0.17 ppm in mysid shrimp. The results of estuarine animal 

chronic testing are tabulated below.

Estuarine/ Marine Chronic Toxicity

Species % ai

NOAEC/LOAEC 

(ppm)

MATC 

(ppm)

Endpoints 

Affected

MRID No.

Author/Year

Study 

Classification

Sheepshead Minnow, 

(Cyprinodon 

variegatus)

88 1.15/2.38 1.65 growth (length 

and weight)

444206-01

R.L. Boeri et al (1997)

Core

Mysid

(Mysidopsis bahia)

88 0.0842/0.173 0.121 number of 

young.female 

after 28 days of 

exposure

444206-02

R.L. Boeri et al (1997)

Core
42

Estuarine/ Marine Chronic Toxicity

Species % ai

NOAEC/LOAEC 

(ppm)

MATC 

(ppm)

Endpoints 

Affected

MRID No.

Author/Year

Study 

Classification

Leptocheirus 

plumulosus

88 Pore water: 1.38 

mg TRR/L

Overlying water: 

0.327 mg TRR/L

N/A No effect on 

survival

47702901

J. Aufderheide (2009)

Supplemental

Toxicity to Terrestrial and Aquatic Plants

Radish was shown to be the most sensitive Dicot for the Tier I toxicity test. The results of Tier 1 

toxicity tests are tabulated below. 

Nontarget Terrestrial Plant Seedling Emergence/Vegetative Vigor Toxicity (Tier I)

Species % ai

Dose

(lb ai/A)

% Response 

and 

Endpoint

Affected

MRID No.

Author/Year

Study 

Classification

6 Dicots/4 monocots 44.2% 0.5 No phytotoxic or other effects 445977-32

D. Schwab 

(1997)

Core

Monocots- corn, oat, 

wheat, onion

Dicots- carrot, cucumber, 

radish, soybean, 

sunflower, tomato

88% 200 grams 

ai/Hectare

(0.18 lb/ai/A)

<25% 438488-02

D. Schwab 

(1994)

Core

The Tier II results indicate that the freshwater diatom is the most sensitive non-vascular aquatic 

plant. Aquatic plant testing (Tier II) results are tabulated below.

Nontarget Aquatic Plant Toxicity (Tier II)

Species % ai EC50 (ppm)

NOAEC

(ppm)

MRID No.

Author/Year

Study 

Classification

Vascular Plants

Duckweed 

Lemna gibba

88 10.6

Slope=1.2

1.86 434145-46

D. P. Milazzo et 

al (1994)

Core

Nonvascular Plants

Green algae

Kirchneria subcapitata

88.2 >105.5

Slope=N/A

4.3 434145-42

D.E. Brock 

(1992)

Core 

Marine diatom

Skeletonema costatum

88 0.227

Slope=4.03

0.167 434145-45

J.S. Hughes and 

M.M. Alexander 

(1993)

Core

Freshwater diatom

Navicula pelliculosa 

88 0.09

Slope=2.59

0.05 434145-43

J.S. Hughes and 

M.M. Alexander 

(1994)

Core

Freshwater diatom

Navicula pelliculosa 

99 Spinosin 

A

31 biomass 8.34 cell density 465053-05 Supplemental
43

Nontarget Aquatic Plant Toxicity (Tier II)

Species % ai EC50 (ppm)

NOAEC

(ppm)

MRID No.

Author/Year

Study 

Classification

Freshwater diatom

Navicula pelliculosa 

94 Factor B 0.16 cell density <0.019 465053-10 Supplemental

Freshwater diatom

Navicula pelliculosa 

96 Factor D 0.22 cell density 0.17 465053-08 Supplemental

Freshwater diatom

Navicula pelliculosa 

100 Spinosin 

D

19 biomass 14.2 465053-02 Supplemental

Blue-green algae

Anabaena flos-aquae 

88 8.9

Slope=4.05

3.9 43414544

J.S. Hughes and 

M.M. Alexander 

(1993)

Core
44

Appendix D: Modeling Results for Aquatic Exposure 

These exposure concentrations were calculated using PRIZM/EXAMS pe5. The assessment is 

conservative in that it assumes the maximum application rate (0.45 lbs ai/A), no flow through the 

field and no dilution from rainfall.

Spinosad Environmental Fate Input Parameters for PRIZM/EXAMS

Parameter Spinosad A Value Source

PC Code 110003 N/A

Water Solubility 

(20 C, distilled water)

89.4 mg/L

Molecular Weight 732 g/mole

Hydrolysis Half-Life (pH 5,7,9) Stable MRID 43507301

Aerobic Soil Metabolism (days) Stable MRID 43507305

Anaerobic Aquatic Metabolism 

(days)

Stable MRID 43507304

Aqueous Photolysis Half-Life (days) Stable MRID 43507302

Soil Water Partition Coefficient 

(Lowest non-sand Koc)

4237 MRID 43507306

Vapor Pressure (torr) 2.4e-10 Product Chemistry

Application Information

Crop Label Rate 

(lbs/ac)

Input

Rate (lbs/ac)

Max App /

Year

Max lb 

a.i./A/ 

season

Min 

Interval 

(days)

Onions for 

seed

0.45 0.45 1 0.45 0

Maximum Exposure Values 

Water Column 

Concentration (ppm)

Sediment Pore Water 

Concentration (ppm)

Peak Value 0.004 0.004

21 Day 0.004 0.004

60 Day 0.004 0.004
45

stored as Onions.out

Chemical: spinosad

PRZM environment: WAonionsNMC.txt modified Thuday, 14 June 2007 at 11:18:44

EXAMS environment: pond298.exv modified Tueday, 26 August 2008 at 06:14:08

Metfile: w24243.dvf modified Tueday, 26 August 2008 at 06:15:56

Water segment concentrations (ppb)

Year Peak 96 hr 21 Day60 Day90 DayYearly

1961 0.2474 0.2137 0.1316 0.09524 0.08153 0.04979

1962 0.6032 0.5363 0.3736 0.2655 0.2341 0.1432

1963 0.4746 0.4406 0.3722 0.3295 0.3133 0.2801

1964 2.115 1.89 0.9444 0.5422 0.4703 0.3588

1965 1.317 1.231 0.9476 0.8608 0.808 0.7619

1966 1.28 1.206 1.111 0.9645 0.941 0.9189

1967 1.175 1.141 1.059 1.004 0.9913 0.9627

1968 1.593 1.522 1.353 1.247 1.228 1.138

1969 1.44 1.406 1.324 1.269 1.257 1.23

1970 2.126 2.061 1.782 1.552 1.53 1.447

1971 1.955 1.883 1.709 1.606 1.603 1.578

1972 1.828 1.794 1.712 1.657 1.644 1.618

1973 2.264 2.194 2.05 1.911 1.835 1.715

1974 2.792 2.663 2.357 2.155 2.109 1.998

1975 2.877 2.767 2.5 2.33 2.291 2.161

1976 2.464 2.431 2.348 2.293 2.28 2.251

1977 3.719 3.508 2.961 2.524 2.447 2.329

1978 2.762 2.729 2.647 2.591 2.579 2.56

1979 2.825 2.791 2.709 2.654 2.641 2.616

1980 3.111 3.047 2.901 2.782 2.754 2.712

1981 3.21 3.15 3.002 2.917 2.9 2.815

1982 3.47 3.395 3.227 3.118 3.085 3.007

1983 3.677 3.59 3.408 3.28 3.221 3.128

1984 3.482 3.443 3.361 3.289 3.275 3.252

1985 3.524 3.491 3.409 3.353 3.341 3.314

1986 4.442 4.294 3.925 3.723 3.699 3.62

1987 5.086 4.873 4.354 3.942 3.86 3.735

1988 4.725 4.61 4.334 4.159 4.119 4.02

1989 4.304 4.27 4.19 4.135 4.123 4.096

1990 5.935 5.672 5.051 4.674 4.589 4.306

Sorted results

Prob. Peak 96 hr 21 Day60 Day90 DayYearly

0.032258064516129 5.935 5.672 5.051 4.674 4.589 4.306

0.0645161290322581 5.086 4.873 4.354 4.159 4.123 4.096

0.0967741935483871 4.725 4.61 4.334 4.135 4.119 4.02

0.129032258064516 4.442 4.294 4.19 3.942 3.86 3.735

0.161290322580645 4.304 4.27 3.925 3.723 3.699 3.62

0.193548387096774 3.719 3.59 3.409 3.353 3.341 3.314
46

0.225806451612903 3.677 3.508 3.408 3.289 3.275 3.252

0.258064516129032 3.524 3.491 3.361 3.28 3.221 3.128

0.290322580645161 3.482 3.443 3.227 3.118 3.085 3.007

0.32258064516129 3.47 3.395 3.002 2.917 2.9 2.815

0.354838709677419 3.21 3.15 2.961 2.782 2.754 2.712

0.387096774193548 3.111 3.047 2.901 2.654 2.641 2.616

0.419354838709677 2.877 2.791 2.709 2.591 2.579 2.56

0.451612903225806 2.825 2.767 2.647 2.524 2.447 2.329

0.483870967741936 2.792 2.729 2.5 2.33 2.291 2.251

0.516129032258065 2.762 2.663 2.357 2.293 2.28 2.161

0.548387096774194 2.464 2.431 2.348 2.155 2.109 1.998

0.580645161290323 2.264 2.194 2.05 1.911 1.835 1.715

0.612903225806452 2.126 2.061 1.782 1.657 1.644 1.618

0.645161290322581 2.115 1.89 1.712 1.606 1.603 1.578

0.67741935483871 1.955 1.883 1.709 1.552 1.53 1.447

0.709677419354839 1.828 1.794 1.353 1.269 1.257 1.23

0.741935483870968 1.593 1.522 1.324 1.247 1.228 1.138

0.774193548387097 1.44 1.406 1.111 1.004 0.9913 0.9627

0.806451612903226 1.317 1.231 1.059 0.9645 0.941 0.9189

0.838709677419355 1.28 1.206 0.9476 0.8608 0.808 0.7619

0.870967741935484 1.175 1.141 0.9444 0.5422 0.4703 0.3588

0.903225806451613 0.6032 0.5363 0.3736 0.3295 0.3133 0.2801

0.935483870967742 0.4746 0.4406 0.3722 0.2655 0.2341 0.1432

0.967741935483871 0.2474 0.2137 0.1316 0.09524 0.08153 0.04979

0.1 4.6967 4.5784 4.3196 4.1157 4.0931 3.9915

Average of yearly averages: 2.13737966666667

Inputs generated by pe5.pl - Novemeber 2006

Data used for this run:

Output File: Onions

Metfile: w24243.dvf

PRZM scenario: WAonionsNMC.txt

EXAMS environment file: pond298.exv

Chemical Name: spinosad

Description Variable Name Value Units Comments

Molecular weight mwt 732 g/mol

Henry's Law Const. henry atm-m^3/mol

Vapor Pressure vapr 2.4e-10 torr

Solubility sol 89.4 mg/L

Kd Kd mg/L

Koc Koc 4237 mg/L

Photolysis half-life kdp 0 days Half-life

Aerobic Aquatic Metabolism kbacw 0 days Halfife

Anaerobic Aquatic Metabolism kbacs 0 days Halfife

Aerobic Soil Metabolism asm 0 days Halfife
47

Hydrolysis: pH 7 0 days Half-life

Method: CAM 4 integer See PRZM manual

Incorporation Depth: DEPI 2.5 cm

Application Rate: TAPP 0.5 kg/ha

Application Efficiency: APPEFF .99 fraction

Spray Drift DRFT 0.01 fraction of application rate applied to pond

Application Date Date 01-04 dd/mm or dd/mmm or dd-mm or dd-mmm

Record 17: FILTRA

IPSCND 1

UPTKF

Record 18: PLVKRT

PLDKRT

FEXTRC 0.5

Flag for Index Res. Run IR EPA Pond

Flag for runoff calc. RUNOFF none, monthly or total(average of entire run)

****************************************************************************

stored as Onionsben.out

Chemical: spinosad

PRZM environment: WAonionsNMC.txt modified Thuday, 14 June 2007 at 11:18:44

EXAMS environment: pond298.exv modified Tueday, 26 August 2008 at 06:14:08

Metfile: w24243.dvf modified Tueday, 26 August 2008 at 06:15:56

Benthic segment concentrations (ppb)

Year Peak 96 hr 21 Day60 Day90 DayYearly

1961 0.06461 0.06375 0.05513 0.0517 0.05108 0.03531

1962 0.1841 0.1841 0.184 0.1822 0.1682 0.1148

1963 0.2778 0.2778 0.2775 0.275 0.2735 0.2516

1964 0.4665 0.4535 0.3568 0.3294 0.3245 0.3069

1965 0.7206 0.7205 0.7197 0.7131 0.7109 0.6868

1966 0.8931 0.893 0.8921 0.881 0.8754 0.8518

1967 0.9306 0.9306 0.9306 0.9306 0.9306 0.9204

1968 1.137 1.137 1.135 1.133 1.13 1.056

1969 1.193 1.193 1.189 1.187 1.187 1.175

1970 1.395 1.395 1.387 1.381 1.38 1.355

1971 1.521 1.521 1.518 1.516 1.516 1.496

1972 1.567 1.566 1.562 1.561 1.561 1.55

1973 1.734 1.734 1.732 1.704 1.675 1.62

1974 1.943 1.943 1.943 1.943 1.943 1.886

1975 2.133 2.133 2.133 2.133 2.133 2.046

1976 2.173 2.173 2.173 2.173 2.173 2.162

1977 2.367 2.364 2.304 2.243 2.233 2.206

1978 2.465 2.465 2.464 2.462 2.461 2.448

1979 2.53 2.53 2.529 2.525 2.523 2.508

1980 2.651 2.651 2.646 2.619 2.612 2.59

1981 2.757 2.757 2.754 2.749 2.741 2.692

1982 2.959 2.958 2.954 2.946 2.934 2.859

1983 3.083 3.083 3.08 3.049 3.029 2.99
48

1984 3.156 3.156 3.153 3.139 3.136 3.119

1985 3.199 3.199 3.199 3.199 3.198 3.185

1986 3.518 3.518 3.518 3.518 3.516 3.427

1987 3.723 3.722 3.687 3.607 3.592 3.559

1988 3.891 3.891 3.891 3.891 3.891 3.842

1989 3.95 3.95 3.95 3.949 3.949 3.936

1990 4.257 4.257 4.257 4.257 4.256 4.089

Sorted results

Prob. Peak 96 hr 21 Day60 Day90 DayYearly

0.032258064516129 4.257 4.257 4.257 4.257 4.256 4.089

0.0645161290322581 3.95 3.95 3.95 3.949 3.949 3.936

0.0967741935483871 3.891 3.891 3.891 3.891 3.891 3.842

0.129032258064516 3.723 3.722 3.687 3.607 3.592 3.559

0.161290322580645 3.518 3.518 3.518 3.518 3.516 3.427

0.193548387096774 3.199 3.199 3.199 3.199 3.198 3.185

0.225806451612903 3.156 3.156 3.153 3.139 3.136 3.119

0.258064516129032 3.083 3.083 3.08 3.049 3.029 2.99

0.290322580645161 2.959 2.958 2.954 2.946 2.934 2.859

0.32258064516129 2.757 2.757 2.754 2.749 2.741 2.692

0.354838709677419 2.651 2.651 2.646 2.619 2.612 2.59

0.387096774193548 2.53 2.53 2.529 2.525 2.523 2.508

0.419354838709677 2.465 2.465 2.464 2.462 2.461 2.448

0.451612903225806 2.367 2.364 2.304 2.243 2.233 2.206

0.483870967741936 2.173 2.173 2.173 2.173 2.173 2.162

0.516129032258065 2.133 2.133 2.133 2.133 2.133 2.046

0.548387096774194 1.943 1.943 1.943 1.943 1.943 1.886

0.580645161290323 1.734 1.734 1.732 1.704 1.675 1.62

0.612903225806452 1.567 1.566 1.562 1.561 1.561 1.55

0.645161290322581 1.521 1.521 1.518 1.516 1.516 1.496

0.67741935483871 1.395 1.395 1.387 1.381 1.38 1.355

0.709677419354839 1.193 1.193 1.189 1.187 1.187 1.175

0.741935483870968 1.137 1.137 1.135 1.133 1.13 1.056

0.774193548387097 0.9306 0.9306 0.9306 0.9306 0.9306 0.9204

0.806451612903226 0.8931 0.893 0.8921 0.881 0.8754 0.8518

0.838709677419355 0.7206 0.7205 0.7197 0.7131 0.7109 0.6868

0.870967741935484 0.4665 0.4535 0.3568 0.3294 0.3245 0.3069

0.903225806451613 0.2778 0.2778 0.2775 0.275 0.2735 0.2516

0.935483870967742 0.1841 0.1841 0.184 0.1822 0.1682 0.1148

0.967741935483871 0.06461 0.06375 0.05513 0.0517 0.05108

0.03531

0.1 3.8742 3.8741 3.8706 3.8626 3.8611 3.8137

Average of yearly averages: 2.03212033333333

Inputs generated by pe5.pl - Novemeber 2006
49

Data used for this run:

Output File: Onions

Metfile: w24243.dvf

PRZM scenario: WAonionsNMC.txt

EXAMS environment file: pond298.exv

Chemical Name: spinosad

Description Variable Name Value Units Comments

Molecular weight mwt 732 g/mol

Henry's Law Const. henry atm-m^3/mol

Vapor Pressure vapr 2.4e-10 torr

Solubility sol 89.4 mg/L

Kd Kd mg/L

Koc Koc 4237 mg/L

Photolysis half-life kdp 0 days Half-life

Aerobic Aquatic Metabolism kbacw 0 days Halfife

Anaerobic Aquatic Metabolism kbacs 0 days Halfife

Aerobic Soil Metabolism asm 0 days Halfife

Hydrolysis: pH 7 0 days Half-life

Method: CAM 4 integer See PRZM manual

Incorporation Depth: DEPI 2.5 cm

Application Rate: TAPP 0.5 kg/ha

Application Efficiency: APPEFF .99 fraction

Spray Drift DRFT 0.01 fraction of application rate applied to pond

Application Date Date 01-04 dd/mm or dd/mmm or dd-mm or dd-mmm

Record 17: FILTRA

IPSCND 1

UPTKF

Record 18: PLVKRT

PLDKRT

FEXTRC 0.5

Flag for Index Res. Run IR EPA Pond

Flag for runoff calc. RUNOFF none, monthly or total(average of entire run)