UNITED STATES ENVIRONMENTAL PROTECTION AGENCY 

WASHINGTON D.C., 20460 

MEMORANDUM 

PC Code: 121301 

DP Barcode: 412033 

March 26, 2014 

Subject: 

To: 

From: 

Through: 

Environmental Fate and Effects Division's Response to Public Comments on the 

Registration Review Preliminary Risk Assessment for Cyromazine 

James Parker, Chemical Review Manager 

Thomas Moriarty, Team Leader 

Neil Anderson, Branch Chief 

Risk Management and Implementation Branch I 

Pesticide Re-evaluation Division (7508P) {!- , 3-- 2 &- ('/ 

Amy Blankinship, M.S., Chemist ~ ~ : r'Lr ,A 3 /z./, (if 

James Hetrick, Ph.D., Senior Science Adviso8tJII1Ul {J. f:(.f/tA.f; 

Environmental Risk Branch III 

Environmental Fate and Effects Division (7507P) 

This document contains the Environmental Fate and Effects Division's (EFED's) responses to 

comments received on the Cyromazine Registration Review Preliminary Risk Assessment (EPAHQ-OPP-2006-0108). Only Syngenta Crop Protection, LLC provided comments on the 

ecological risk assessment. Based on these comments and a reanalysis of the data, EFED has 

updated the risk assessment conclusions. The table below summarizes the risk conclusions for 

direct effects to listed species. Based on the reanalysis of the data, the levels of concern are no 

longer exceeded for acute and chronic exposure to avian or mammalian taxa for any foliarapplied crop, except for potatoes for birds. Additionally, potential chronic risk to aquatic 

invertebrates is anticipated to be low. 
Listed Plant Taxon Potential Direct Effects 

Terrestrial and semiaquatic plants – monocots and dicots 

Uncertain- Phytotoxicity reported (nature of plant injury unknown). Runoff EECs to semi-aquatic areas, b

than reported toxicity levels, so potential effects may be spatially limited. For spray drift exposure, potentiamonocots (via ground and aerial application) and for ground application to dicots the likelihood of effects is there may be potential direct effects to dicots from aerial application in a spatially limited area from aerial a

(EECs ≥ toxicity values for ≤72 feet off-field) 

Aquatic plants No effect 

Listed Animal Taxon 

Potential Direct Effects 

Acute Notes Chronic 

Terrestrial invertebrates Yes

1

 Potential direct effects to birds and 

mammals from onion seed use. 

 For foliar application to all crops, except 

potato, acute avian (surrogates for reptiles and terrestrial-phase amphibians) and mammalian RQ values were less than LOC 

 Uncertain for foliar application to 

potatoes, as screening-level RQ values would not exceed the acute LOC for birds (also surrogate for reptiles and terrestrial amphibians) if the application scenario were modified by reducing the total number of applications from 3 to 2. 

 For foliar applications to potatoes, for 

reptiles and amphibians, RQs did not exceed LOC (except for animals consuming herbivorous mammals) using model default diet assumptions; however reptiles and amphibian diets expected to vary between species and this conclusion 

Yes 

2

 Potential di

mammals f

 For foliar a

except pota(surrogates phase amphRQ values w

 Uncertain f

potatoes, as values wouLOC for birreptiles and the applicatmodified by number of 1. 

 Chronic exp

soil amendm

3 Based on the estim

Mammals See footnote 1 See footnote 2 Birds See footnote 1 See footnote 2 Reptiles See footnote 1 See footnote 2 Amphibians See footnote 1 See footnote 2 Freshwater fish No effect No effect Freshwater invertebrates No effect No effect3 Molluscs No effect ND Estuarine/marine fish No effect No effect
Listed Plant Taxon Potential Direct Effects 

Estuarine/marine invertebrates No effect 

may not apply across all species. If apply modified application scenarios above, then screening-level RQ values would not exceed the acute LOC. 

 No effect for amending soil with 

cyromazine-treated manure use. 

No effect3 

and toxicity values fmidges, the RQs did effects may be limiteColeoptera order (bepest, and while potenaquatic invertebrates and other orders not there were effects reterrestrial Coleopterthere are other listed including Coleoptera Based on the reportecyromazine use, the to other listed aquatiand dragonfly), is unon the available toxispecies in these ordeor more times more available species. Taquatic invertebrates 
1. Syngenta Crop Protection Comment: Page 9, Section 1. Executive Summary, B. 

Nature of Stressor 

Syngenta disagrees with EPA’s description on the persistence of cyromazine in soil. 

The Agency stated that cyromazine is persistent in soil because the half-lives are 

greater than 100 days. Syngenta stated that the half-lives of cyromazine in soil range 

from 62 to 142 days. This range of half-lives is classified as slightly degradable (t1/2= 

60 to 180 days) according to the FAO definition for degradability in soil. 

EFED Response: EPA agrees that cyromazine is slightly degradable in soil. An 

exact qualifier on the degradation potential of cyromazine in soil is subjective 

because it is dependent on numerous factors including soil type, half-life analysis, soil 

temperature, soil moisture, etc. EPA believes that cyromazine is moderately 

persistent to persistent in soil. Below is an analysis showing that the upper 90th

confidence bound on the mean half-life can range from 147 to 250 days. These data 

would suggest that cyromazine is slightly degradable to very slightly degradable 

according to the FAO classification. The elimination of the half-life in muck soil 

increases the upper 90th confidence bound on the mean half-life of cyromazine into 

the very slightly degradable FAO classification. 

Table 1. Summary of Aerobic Soil Metabolism Half-lives 

Study 

Soil 

Type Soil Texture All Soils Mineral Soils 

157458 Organic Sand-Muck 107 107 107 

157458 Mineral Sandy Loam 142 142 142 142 142 142 

43767901 Mineral 

Sandy Loam 

(Linear SFO) 62 62 

43767901 Mineral 

Sandy Loam 

( Nonlinear SFO) 27.3 27.3 

43767901 Mineral 

Sandy Loam 

(DFOP) 37.1 37.1 

Mean 103.67 95.37 92.1 89.55 102 84.65 

Standard Deviation 40.10 53.41 58.78 74.18 56.57 81.11 

90th Confidence Bound on 

the Mean 

147.34 153.52 156.10 250.99 225.12 261.17 

2. Syngenta Crop Protection Comment: Pages 26-27, Section 3. Environmental 

Fate Characterization and Modeling Input Parameters 

Syngenta stated that field dissipation half-lives of cyromazine range from 83 to 236 days 

instead of the reported 93 to 240 days. Additionally, the half-life for cyromazine in 

chicken manure should be 493 days (MRID 156483). The registrant also believes that 

the mobility classification based on the FAO mobility classification (moderately mobile 

to mobile) instead of a general statement of “generally less than 2”. 

EFED Response: EPA agrees with the registrant that the field dissipation half-lives for 

cyromazine range from 83 to 236 days, and the half-life of cyromazine in chicken manure 
5 

is 493 days. EPA agrees the FAO soil mobility classification is moderately mobile to 

mobile. 

3. Syngenta Crop Protection Comment: Page 28, Table 5: Input Parameters in 

GENEEC and PE5 Modeling to Estimate Cyromazine Concentrations Resulting 

From the Uses on Crops, Ornamentals, and Soil Amendment (Manure and Feed 

–throughs, Mushroom Compost) 

Syngenta is unable to validate the source of the single value soil metabolism half-life of 

150 days used in GENEEC and PRZM/EXAMS modeling. Based on current model input 

parameter guidance, Syngenta believes the correct half-life for modeling is 147.38 days 

(90th percentile confidence bound on the mean half-life). This value was calculated using 

half-lives of 62 days, 142 days, and 107 days. Because of the recommended change in 

half-life and the absence of aerobic aquatic metabolism data, the aerobic aquatic 

metabolism half-life should be 294.76 days (2 x 147.38 days). The anaerobic aquatic 

metabolism half-life should be 585.6 days (2 x 97.6 days x 3). 

Syngenta stated that the Kd model is more appropriate for modeling because the 

coefficient of variation for Kd is less than the coefficient of variation for Koc. Therefore, 

the modeling should be conducted on the mean Kd (2.25 ml/g) instead of the lowest Kd

for a non-sand soil (3.9 ml/g). Syngenta stated that the Kd of 17 ml/g, as noted in 

footnote 3 in Table 5, is for an organic soil (22.9%). They recommend that this Kd

should not be used in calculating the soil:water partitioning coefficient for cyromazine. 

Also, the registrant stated an incorrect soil texture (silt loam) is reported for the soil with 

a Kd of 3.87 ml/g. The correct soil texture is loam. 

 

EFED Response: EPA agrees with the model input issues raised by Syngenta except for 

the half-life of the anaerobic aquatic metabolism half-life. As per current EFED input 

parameter guidance, the soil metabolism half-life should be 147.38 days (90th percentile 

confidence bound on the mean half-life of 62 days, 142 days, and 107 days) 

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

Additionally, the aerobic aquatic metabolism half-life for cyromazine would be 294.76 

day (147.38 days x 2). The lowest non-sand Kd (3.39 ml/g) for cyromazine should 

actually be the mean Kd for mineral soils (2.3 ml/g). EPA believes the anaerobic aquatic 

metabolism half-life should be 300 days (100 days x 3) because of the available data for a 

single soil in an anaerobic soil metabolism study (MRID 43767902). Table 2 below 

(Table 5 in the preliminary risk assessment) shows the revised model input table for 

GENEEC modeling. Table 3 (Table 6 in the preliminary risk assessment) shows that the 

revised model input parameters do not substantially alter the EECs as presented in the 

preliminary risk assessment. 

 
6 

Table 2. Input Parameters Used in GENEEC Modeling to Estimate Cyromazine Concentrations 

Resulting From the Uses on Crops, Ornamentals, and Soil Amendment (Manure and Feed-throughs, 

Mushroom Compost) 

Input Parameter Value for Cyromazine Reference 

Solubility in Water (mg/L at 25 oC) 1.36 x 105

 mg/L MRID 43061200 

Hydrolysis Half-life (t1/2 at pH 7) Stable at pH 5, 7, and 9 MRID 103148 

Aquatic Photolysis Half-life (days; t1/2 at pH 7) Stable in water at pH 7 MRID 103149 

Aerobic Soil Metabolism [upper 90th percentile confidence 

bound on the mean half-life value (t1/2; days)] 

147.3 MRIDs 157458, 

43767901 

Aerobic Aquatic Metabolism Half-life [water column; upper 

90th percentile confidence bound on the mean half-life value 

(t1/2; days)] 

147.3 days x 2 = 294.6 

days 

EFED Input 

Parameter Guidance 

Average Adsorption Rate Coefficient 

(Kads; mL/g) 

Average Kd= 2.3 MRIDs 103139, 

103150, 103165 

1 The 90th percent upper bound of mean of 107, 142, 62 days is 147.3 days (http:/www.epa.gov/oppefed1/models 

ater/input_parameter_guidance.htm). 

2 Kads 0.52 (sand), 2.37 (sandy clay loam), 3.87 ( loam). The Kd from an organic soil ( 17 ml/g) was excluded 

because it has an extremely high soil organic matter content (SOM= 22%) 

Table 3. Comparison of Tier I Surface Water for Cyromazine EECs for Registered Crop Uses for the 

Original Input Parameters and Revised Input Parameters. Crops Application Information Estimated Environmental Concentrations (μg/L) 

Application 

Rate 

(lbs ai/A) 

Number of 

Applications 

Seasonal 

Application 

Rate 

(lbs ai/A) 

Peak 21-Day Average 60-Day Average 

Original 

EEC 

Revised 

EEC 

Original 

EEC 

Revised 

EEC 

Original 

EEC 

Revised 

EEC 

Lima beans, 

dried beans, 

hanover 

salad, bulb 

vegetables, 

cucurbit, 

brassica 

leafy, celery, 

head lettuce, 

peppers, 

abyssinian 

seakale 

cabbage, 

turnip greens, 

tomatoes, 

0.125 6 0.75 29.95 32.44 29.23 31.79 27.9 30.55 

Leafy 

vegetables 

(minus 

brassica 

leafy, celery, 

head lettuce) 

0.125 5 

0.625 

25.09 27.34 24.49 26.86 23.37 25.82 

Potatoes 

(Colorado 

potato beetle 

and 

leafminer) 

0.249 3 0.747 30.3 33.72 29.57 33.04 28.23 31.75 
7 

4. Syngenta Crop Protection Comment: 

The registrant could not replicate the PRZM/EXAMS modeling in Table 6 of the 

preliminary risk assessment. 

EFED Response: EPA reran the PRZM/EXAMS modeling. Table 4 includes the 

revised input parameters for the PRZM/EXAMS modeling. As per current EFED input 

parameter guidance, the soil metabolism half-life was changed to 147.38 days (90th

percentile confidence bound on the mean half-life of 62 days, 142 days, and 107 days) 

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

Additionally, the aerobic aquatic metabolism half-life for cyromazine was changed to 

294.76 day (147.38 days x 2). Additionally, The lowest non-sand Kd (3.39 ml/g) for 

cyromazine was changed to represent the mean Kd for mineral soils (2.3 ml/g). Also, the 

anaerobic aquatic metabolism half-life was changed to 300 days (100 days x 3) because 

of the available data for a single soil in an anaerobic soil metabolism study (MRID 

43767902). Table 5 shows the 1 in 10 year sediment, pore water, and water column 

EECs. The PRZM/EXAMS input files are shown in Appendix A. 

Table 4. Input Parameters Used in PRZM/EXAMS Modeling to Estimate Cyromazine Concentrations 

Resulting From the Potato Use 

Input Parameter (Symbol; Unit) Value for Cyromazine Reference 

Molecular Weight 166.19 

SRC Database 

(http://www.srcinc.com/what-wedo/databaseforms.aspx?id=386) 

Henry’s constant (25 oC) 5.65 x 10-14 atm-m3

 / mole @ 

25oC

SRC Database 

(http://www.srcinc.com/what-wedo/databaseforms.aspx?id=386) 

Vapor Pressure (torr) 3.36 x 10-9 torr @ 25oC

SRC Database 

(http://www.srcinc.com/what-wedo/databaseforms.aspx?id=386) 

Solubility in Water (mg/L at 25 oC) 1.36 x 105

 mg/L MRID 43061200 

Hydrolysis Half-life (t1/2 at pH 7) Stable at pH 5, 7, and 9 MRID 103148 

Aquatic Photolysis Half-life (days; t1/2 at 

pH 7) Stable in water at pH 7 MRID 103149 

Aerobic Soil Metabolism [upper 90th

percentile confidence bound on the mean 

half-life value (t1/2; days)] 

147.3 MRIDs 157458, 43767901 

Aerobic Aquatic Metabolism Half-life 

[water column; upper 90th percentile 

confidence bound on the mean half-life 

value (t1/2; days)] 

147.3 days x 2 = 294.6 days EFED Input Parameter Guidance 

Anaerobic Aquatic Metabolism Half-life 

(t1/2; days) 100 days X 3 = 300 EFED Input Parameter Guidance 

Anaerobic Soil Metabolism Half-life (t1/2; 

days) 100 days MRID 43767902 

Average Adsorption Rate Coefficient 

(Kads; mL/g) Average Kd= 2.3 MRIDs 103139, 103150, 103165 
8 

Table 5. PRZM/EXAMS Modeling to EECs for Cyromazine Resulting From the Potato Use 

Crop Environmental 

Compartment 

Estimated Environmental Concentration 

(μg/L) 

Peak 21-day average 60-day average 

Potatoes (Colorado potato beetle and 

leafminer) 

Scenario: MEpotatoSTD4 

Application Date: June 1st 

Water Column (ppb) 7.337 6.990 6.639 

Pore Water (ppb) 5.086 5.075 5.016 

Sediment (μg/kg) 13.325 13.295 13.143 

5. Syngenta Crop Protection Comment, Cover Letter, Pg. 5 Line 12 to Pg. 6 : Syngenta 

supports the use of additional refinements, which should include the best available 

higher-tier risk assessment data and methodologies, when making final effect 

determinations for listed species. 

EFED Response: EPA plans to address many of the concerns raised as part of the 

implementation plan for assessing the risks of pesticides to listed species based on the 

recommendations of the April 2013 National Academy of Sciences (NAS) report. 

The NAS report, available at http://www.nap.edu/catalog.php?record_id=18344, outlines 

recommendations on specific scientific and technical issues related to the development of 

pesticide risk assessments that are compliant with the Endangered Species Act and the 

Federal Insecticide, Fungicide, and Rodenticide Act. In November, the EPA, along with the 

U.S. Fish & Wildlife Service (USFWS), the National Marine Fisheries Service (NMFS) 

(collectively, the Services), and the U.S. Department of Agriculture (USDA), released a 

summary of their joint Interim Approaches for assessing risks to listed species from 

pesticides. The Interim Approaches were developed jointly by the Agencies in response to 

the NAS’ recommendations and reflect a common approach to risk assessment shared by the 

Agencies as a way of addressing scientific differences between EPA and the Services. The 

joint Interim Approaches were released prior to the stakeholder workshop held on November 

15, 2013. EPA is presenting the joint Interim Approaches at the December 2013 PPDC and 

SFIREG meetings, allowing additional opportunities for stakeholders to comment on the 

Interim Approaches. The Agencies will consider public comments on the Interim 

Approaches prior to implementing them. The Agencies intend to jointly implement these 

approaches as part of a phased iterative process. EPA will refine its listed species risk 

assessments based on these interim approaches. The details of the joint Interim Approaches 

are contained in the white paper “Interim Approaches for National-Level Pesticide 

Endangered Species Act Assessments Based on the Recommendations of the National 

Academy of Sciences April 2013 Report,” dated November 1, 2013, available at 

http://www.epa.gov/espp/2013/nas.html. 
9 

6. Syngenta Crop Protection Comment, Cover Letter Pg 4 and Section V, Pg. 57, Lines 

1-15: Syngenta agrees with EPA’s initial determination of “no effects” on listed aquatic 

invertebrates. Syngenta provided a summary regarding their co-occurrence analyses for 

several listed aquatic invertebrates, for which they state that potential exposure of 

cyromazine to those organisms is limited. 

EFED Response: In the preliminary risk assessment for cyromazine (USEPA 2013), the 

preliminary determination for aquatic invertebrates for potential direct effects from chronic 

exposure was reported as ‘no effect’. However, this preliminary determination was 

characterized in that chronic RQs were below the LOC using data from aquatic crustaceans 

but other data suggested that other aquatic invertebrates (particularly in the Diptera order) 

may be potentially affected by chronic exposure. Additionally, while data on aquatic species 

in the Coleoptera order were not available, data on terrestrial Coleoptera species also suggest 

potential direct effects. At the time of the assessment, there were no listed species in the 

Diptera order, but there were other listed aquatic invertebrates including Coleoptera beetles 

and a dragonfly. According to the analysis in the risk assessment, based on the reported 

geographic areas of cyromazine use, the potential for direct effects to other listed aquatic 

invertebrates (beetles and dragonfly) may be limited, but this was uncertain. Further 

refinements to the preliminary risk assessment were conducted and results are presented in 

item #8 of this response. 

7. Syngenta Crop Protection Comment, Pg 19-21, Table 4: Several of the MRID 

numbers listed in the risk assessment appear to be incorrect, correct MRID numbers 

were provided. 

EFED Response: The MRID numbers reported by Syngenta are correct. The risk 

assessment used accession numbers reported in the data evaluation records (DERs) and 

incorrectly labeled them as MRID numbers. However, the MRID for the mallard chronic 

reproduction study reported in the risk assessment was correct. 

8. Syngenta Crop Protection Comment, Pg. 20, Table 4 and Section III, Pg 36, Lines 

30-33: Based on the study report, the endpoint for the chronic estuarine/marine 

invertebrate study (MRID 48691501) should be changed to 0.25 mg a.i./L, based on 14-

day male length, and the study should be upgraded to acceptable. 

EFED Response: Upon review of the data, the EFED reviewer’s conclusion regarding 14-

day male lengths differed from the study author. While the inhibition of length at all levels 

was rather small in magnitude (4 to 8% of control), there was a general dose-responsive 

decreasing trend for which all treatment groups were statistically different from the control. 

However, given the estimated environmental concentrations (EECs) (in the preliminary risk 

assessment) and the magnitude of effect observed for this endpoint compared to the control, 

the preliminary risk assessment concluded that the likelihood of adverse effects from chronic 

exposure of cyromazine to estuarine-marine invertebrates, particularly for crustaceans, was 

also predicted to be low. 

Based on comments received for the preliminary risk assessment and adjustments to the 

model input parameters, aquatic EECs were recalculated and the recalculated aquatic EECs 
10 

are similar to the EECs in the preliminary assessment. In the preliminary assessment, the 

highest calculated overlying water concentration was greater than the NOAEC established in 

a chronic midge development test, therefore, it was determined that there was a potential for 

direct effects to sediment-dwelling organisms (such as in the Diptera order) from chronic 

exposure to cyromazine. However, after comparison to the recalculated value, the overlying 

water EEC (6.99 μg a.i./L) is now 2 times lower than the reported NOAEC value (14.5 μg 

a.i./L). Therefore, based on the available data, the preliminary conclusion of low likelihood 

of potential direct effects from chronic exposure may be applied to a broader group of 

aquatic invertebrates to include organisms in the Diptera order. The preliminary conclusion 

of “Based on the reported geographic areas of cyromazine use, the potential for direct effects 

to other listed aquatic invertebrates (beetles and dragonfly) is uncertain” remains true. 

However, based on the available acute and sub-chronic data for aquatic crustaceans and 

midges, acute toxicity studies are classified as slightly to practically non-toxic (48-h EC/LC50

values of 9.1 mg/L (Daphnia) to ≥88.7 mg a.i./L (Daphnia magna and midges) and a 7-day 

LC50 of 1.95 mg a.i./L for mysid shrimp). Based on this toxicity data and the re-calculated 

EECs (highest peak EEC = 33.7 μg a.i./L for use of potato), acute toxicity values for other 

aquatic invertebrates would need be approximately three to fourteen times more sensitive 

than the currently available data to exceed the acute listed level of concern (LOC). Similarly 

for chronic exposure, based on the available aquatic invertebrate chronic toxicity data and 

EECs (highest peak EEC = 31.8 μg a.i./L for use of potato), a chronic NOAEC toxicity value 

for other species of aquatic invertebrates (Daphnia magna NOAEC = 0.31 mg a.i./L) would 

need to be approximately 10 times lower than this chronic toxicity value for freshwater 

crustaceans. The chronic mysid shrimp study did not have a definitive NOAEC value (<0.13 

mg a.i./L) which was based on a slight, but significant, effect on male body length (4-8%); a 

significant effect on survival was also observed with a NOAEC value of 1.14 mg a.i./L. The 

current highest EEC is approximately 4 times lower than the non-definitive value for the 

mysid shrimp, therefore other aquatic invertebrates would need to be about four times more 

sensitive than mysids to exceed the chronic LOC. Based on these analyses, potential acute 

and chronic risk to aquatic invertebrates is anticipated to be low. 

9. Syngenta Crop Protection Comment, Pg. 21, Table 4 and Section III, Pg. 38, Lines 

14 and 15: Syngenta supports a NOAEL of 1000 mg/kg-diet for the mammalian twogeneration study, based on reduced body weights (MRID 00103197). However, they 

suggest basing the NOAEC on an empirically derived value using measured body 

weights, feed consumption and dietary concentrations. Raw data supporting these 

calculations were subsequently supplied by Syngenta. 

EFED Response: This study was re-evaluated by the Health Effects Division (HED) and the 

data evaluation record (DER) for this study (MRID 00103197) was updated. Based on the 

updated DER, the most sensitive NOAEL was 1000 mg/kg-diet based on decreased body 

weights for both males and females in the F0 and F1 generations (or 50 mg/kg/day (ppm) 

using the default conversion of 1 ppm = 0.05 mg/kg or 70, 54.6, 84.5, 70.5 mg/kg/day for F0 

males, F1 males, F0 females, F1 females, respectively, using actual food consumption data 

and actual test material dietary concentrations). As there were reported effects on body 

weights for both males and females in the F0 and F1 groups, the lowest empirically derived 

NOAEL value (54.6 mg/kg/day) as well as the nominal value (1000 mg/kg-diet) were used as 
11 

the reported chronic mammalian toxicity value and used as the input value in the T-REX 

model to calculate chronic mammalian RQs. 

10. Syngenta Crop Protection Comment, Section III, Analysis 2, Pg. 31, Lines 5-7: The 

use of a 35-day foliar dissipation half-life is overly conservative and suggests that the 

value can be refined. 

EFED Response: In the preliminary risk assessment, an evaluation of the potential foliar 

dissipation half-life was discussed. Based on the available information, it appeared that 

cyromazine may dissipate on some types of foliage (i.e., leafy vegetables which may be 

similar to the broadleaf plant category in T-REX) with calculated half-lives generally less 

than 14 days with 7 days in some cases (based on magnitude of residue studies; MRID 

41976301, Acc. 00150744). But the data also seemed to suggest that for some types of 

plants, cyromazine did not readily dissipate during the course of the study (i.e., tomatoes, 

cucurbits; MRID 42255101, 42116001). Additionally, dissipation data for grasses were not 

available, therefore, there was uncertainty in the potential dissipation rate for these other 

dietary groups, of which short grass results in the highest EECs. 

Using the available data, a 90th upper confidence limit foliar dissipation half-life was 

calculated and determined to be 7 days. This value is based on magnitude of residue data for 

leafy vegetables (lettuce, celery, spinach), melons (cantaloupe, cucumber, honeydew melon, 

summer squash, watermelon), tomatoes and peppers (MRIDs 42116001, 47010701, 

47011801, 41976301, and 42255101). The data showed that cyromazine did dissipate on 

leafy vegetables, but was more persistent on melons and tomatoes. Data on grasses were not 

available. Therefore, the initial uncertainties in that the available data may not be appropriate 

for all dietary groups (e.g., grasses) still remains. However, the foliar dissipation half-life 

value calculated from empirically derived data as opposed to a default value (35 days) was 

used to revise the terrestrial EECs and RQs using the model T-REX. 

Terrestrial EECs and RQs were recalculated using the revised foliar dissipation half-life 

value (7 days) and the chronic mammalian NOAEL value (54.6 mg/kg/day). Other input 

values were based on the maximum use rates as reported by the labels (same as used in the 

preliminary assessment). The EECs and subsequent RQ values are presented in the tables 

below. 

Table 6. Avian Dose-Based Cyromazine Upper Bound EEC Values for Various Crops 

Application Rate 

(crop) 

Size 

Class 

(g)1

Avian Dose-Based EECs (mg/kg-bw) 

Dietary Item 

Short 

Grass 

Tall 

Grass 

Broadleaf 

plants 

Fruits/ 

pods Arthropods

Seeds 

0.125 lb a.i./A @ 6 apps/7-d interval 

(succulent beans; lima beans; dried 

beans; hanover salad; bulb veg; 

cucurbits; brassica leafy; celery, head 

lettuce; leafy veg; peppers; sea kale 

cabbage, turnip greens 

20 67.27 30.83 37.84 4.20 

26.35 0.93 

100 38.36 17.58 21.58 2.40 

15.02 0.53 

1000 17.17 7.87 9.66 1.07 6.73 0.24 
12 

1

 Adjusted LD50 values (mg/kg-bw): 20 g – 1229; 100 g – 1565; 1000 g– 2210 

Table 7. Mammalian Dose-Based Cyromazine Upper Bound EEC Values for Various Crops 

1

 Adjusted LD50 values (mg/kg-bw): 15 g – 2305; 35 g – 1865; 1000 g – 806.8; LD50 values calculated using 

initial body weight – study reported range from 20-30 g (individual values not reported), so used 25 grams in 

TREX. 

2

 Adjusted NOAEL values (mg/kg-bw): 15 g – 109.9; 35 g – 88.9; 1000 g –38.5 

0.249 lb a.i./A @3 apps/7-d interval 

(potatoes) 

20 119.11 54.59 67.00 7.44 46.65 

1.65 

100 67.92 31.13 38.20 4.24 

26.60 0.94 

1000 30.41 13.94 17.10 1.90 11.91 0.42 

0.125 lb a.i./A @ 3 apps /7-d interval 

(repeat 3 apps @ 7-d interval 21-d after 

last of first 3 apps) 

(ornamentals) 

20 61.66 28.26 34.68 3.85 24.15 

0.86 

100 35.16 16.12 19.78 2.20 

13.77 0.49 

1000 15.74 7.22 8.86 0.98 6.17 0.22 

Application Rate 

(crop) 

Size 

Class 

(g)1

Mammalian Dose-Based EECs (mg/kg-bw) 

Dietary Item 

Short 

Grass 

Tall 

Grass 

Broadleaf 

plants 

Fruits/ 

pods Arthropods

Seeds 

0.125 lb a.i./A @ 6 apps/7-d interval 

(succulent beans; lima beans; dried 

beans; hanover salad; bulb veg; 

cucurbits; brassica leafy; celery, head 

lettuce; leafy veg; peppers; sea kale 

cabbage, turnip greens 

15 56.31 25.81 31.68 3.52 

22.06 0.78 

35 38.92 17.84 21.89 2.43 

15.24 0.54 

1000 9.02 4.14 5.08 0.56 3.53 0.13 

0.249 lb a.i./A @3 apps/7-d interval 

(potatoes) 15 99.71 45.70 56.09 6.23 39.05 

1.38 

35 68.91 31.58 38.76 4.31 

26.99 0.96 

1000 15.98 7.32 8.99 1.00 6.26 0.22 

0.125 lb a.i./A @ 3 apps /7-d interval ( 

repeat 3 apps @ 7-d interval 21-d after 

last of first 3 apps) 

(ornamentals) 

15 51.62 23.66 29.04 3.23 20.22 

0.72 

35 35.68 16.35 20.07 2.23 

13.97 0.50 

1000 8.27 3.79 4.65 0.52 3.24 0.11 
13 

Table 8. Dietary-Based Cyromazine EEC Values for Various Crops 

Application Rate (crop) 

Dietary-Based EECs (mg/kg-diet) 

Dietary Item 

Short 

Grass 

Tall 

Grass 

Broadleaf 

plants Fruits/pods/seeds Arthropods

0.125 lb a.i./A @ 6 apps/7-d interval 

(succulent beans; lima beans; dried beans; hanover salad; 

bulb veg; cucurbits; brassica leafy; celery, head lettuce; 

leafy veg; peppers; sea kale cabbage, turnip greens 

59.06 27.07 33.22 3.69 23.13 

0.249 lb a.i./A @3 apps/7-d interval 

(potatoes) 104.58 47.93 58.83 6.54 40.96 

0.125 lb a.i./A @ 3 apps /7-d interval (repeat 3 apps @ 7-d 

interval 21-d after last of first 3 apps) 

(ornamentals) 

54.14 24.81 30.45 3.38 21.21 

Table 9. Avian Acute Dose-Based RQ Values for Foliar Application of Cyromazine. 

Application rate 

(crop) 

Functional Feeding Group 

Dietary Item 

20 g bird 100 g bird 1000 g bird 

Acute1 Acute1 Acute1

0.125 lb a.i./A @ 6 

apps/7-d interval 

(succulent beans; lima 

beans; dried beans; 

hanover salad; bulb 

veg; cucurbits; 

brassica leafy; celery, 

head lettuce; leafy 

veg; peppers; sea kale 

cabbage, turnip greens 

Herbivores/Insectivores 

 Short Grass 0.06 0.02 0.01 

 Tall Grass 0.03 0.01 <0.01

 Broadleaf plants 0.03 0.01 <0.01

 Fruits/pods <0.01 <0.01 <0.01

 Arthropods 0.02 0.01 <0.01

 Seeds <0.01 <0.01 <0.01

0.249 lb a.i./A @3 

apps/7-d interval 

(potatoes) 

Herbivores/Insectivores 

 Short Grass 0.10 0.04 0.01 

 Tall Grass 0.04 0.02 0.01 

 Broadleaf plants 0.05 0.02 0.01 

 Fruits/pods 0.01 <0.01 <0.01 

 Arthropods 0.04 0.02 0.01 

 Seed <0.01 <0.01 <0.01 

0.125 lb a.i./A @ 3 

apps /7-d interval 

(repeat 3 apps @ 7-d 

interval 21-d after last 

of first 3 apps) 

(ornamentals) 

Herbivores/Insectivores 

 Short Grass 0.05 0.02 0.01 

 Tall Grass 0.02 0.01 <0.01 

 Broadleaf plants 0.03 0.01 <0.01 

 Fruits/pods <0.01 <0.01 <0.01 

 Arthropods 0.02 0.01 <0.01 

 Seeds <0.01 <0.01 <0.01 
14 

Application rate 

(crop) 

Functional Feeding Group 

Dietary Item 

20 g bird 100 g bird 1000 g bird 

Acute1 Acute1 Acute1

Bolded RQ values exceed the acute listed LOC of 0.1; 1 Acute RQ = (upper bound dose-based EEC, mg/kg-bw) / (LD50; mg/kg-bw). 
15 

Table 10. Avian Chronic Dietary RQ values from Foliar Application of Cyromazine. 

Application Rate 

(Crop) Dietary Item Chronic RQ 1

0.125 lb a.i./A @ 6 apps/7-d interval 

(succulent beans; lima beans; dried beans; hanover 

salad; bulb veg; cucurbits; brassica leafy; celery, 

head lettuce; leafy veg; peppers; sea kale cabbage, 

turnip greens

Short Grass 0.20 

Tall Grass 0.09 

Broadleaf plants 0.11 

Fruits/pods/seeds 0.01 

Arthropods 0.08 

 

0.249 lb a.i./A @3 apps/7-d interval 

(potatoes)

Short Grass 1.39 

Tall Grass 0.64 

Broadleaf plants 0.78 

Fruits/pods/seeds 0.09 

Arthropods 0.55 

 

0.125 lb a.i./A @ 3 apps /7-d interval (repeat 3 

apps @ 7-d interval 21-d after last of first 3 apps) 

(ornamentals) 

Short Grass 0.72 

Tall Grass 0.33 

Broadleaf plants 0.41 

Fruits/pods/seeds 0.05 

 Arthropods 0.28 

Bold values exceed the chronic LOC of 1.0 

1 Chronic RQ = (EEC, mg/kg-diet) / chronic NOAEC, mg/kg-diet; where the chronic NOAEC is 75 mg/kg-diet 

Table 11. Mammalian Acute RQ Values for Foliar Application to Potatoes of Cyromazine 

Application Rate 

(Crop) 

Functional Feeding 

Group 

Dietary Item 

15 g mammals 35 g mammals 1000 g mammals 

Acute1 Acute1 Acute1

0.249 lb a.i./A @3 apps/7-d interval 

(potatoes) 

Herbivores/Insectivores 

 Short Grass 0.04 0.04 0.02 

 Tall Grass 0.02 0.02 0.01 

 Broadleaf plants 0.02 0.02 0.01 

 Fruits/pods <0.01 <0.01 <0.01 

 Arthropods 0.02 0.01 0.01 

 Seeds <0.01 <0.01 <0.01 

1 Acute RQ = (upper bound dose-based EEC, mg/kg-bw) / (LD50; mg/kg-bw). 
16 

Table 12. Mammalian Chronic Dose-based RQ values for Foliar Application of Cyromazine 

Application Rate 

(Crop) 

Functional Feeding Group 

Dietary Item 

15 g mammals 35 g mammals 1000 g mammals 

Chronic1 Chronic1 Chronic1

0.125 lb a.i./A @ 6 

apps/7-d interval

(succulent beans; lima 

beans; dried beans; 

hanover salad; bulb 

veg; cucurbits; 

brassica leafy; celery, 

head lettuce; leafy 

veg; peppers; sea kale 

cabbage, turnip greens

Herbivores/Insectivores 

 Short Grass 0.47 0.40 0.21 

 Tall Grass 0.22 0.18 0.10 

 Broadleaf plants 0.26 0.23 0.12 

 Fruits/pods 0.03 0.03 0.01 

 Arthropods 0.18 0.16 0.08 

 Seeds 0.01 0.01 <0.01 

0.249 lb a.i./A @3 

apps/7-d interval 

(potatoes) 

Herbivores/Insectivores 

 Short Grass 0.83 0.71 0.38 

 Tall Grass 0.38 0.33 0.17 

 Broadleaf plants 0.47 0.40 0.21 

 Fruits/pods 0.05 0.04 0.02 

 Arthropods 0.33 0.28 0.15 

 Seeds 0.01 0.01 0.01 

0.125 lb a.i./A @ 3 

apps /7-d interval 

(repeat 3 apps @ 7-d 

interval 21-d after last 

of first 3 apps) 

(ornamentals) 

Herbivores/Insectivores 

 Short Grass 0.43 0.37 0.20 

 Tall Grass 0.20 0.17 0.09 

 Broadleaf plants 0.24 0.21 0.11 

 Fruits/pods 0.03 0.02 0.01 

 Arthropods 0.17 0.14 0.08 

 Seeds 0.01 0.01 <0.01 

Bold values exceed the chronic LOC of 1 

1 Chronic RQ = (upper bound dose-based EEC, mg/kg-bw) / (NOAEC; mg/kg-bw). 

Table 13. Mammalian Chronic Dietary-based RQ values for Foliar Application to Potatoes for 

Cyromazine 

Application Rate 

(Crop) Dietary Item Chronic RQ 1

0.249 lb a.i./A @3 apps/7-d interval 

(potatoes)

Short Grass 0.10 

Tall Grass 0.05 

Broadleaf plants 0.06 

Fruits/pods/seeds 0.01 

Arthropods 0.04 

1 Chronic RQ = (EEC, mg/kg-diet) / chronic NOAEC, mg/kg-diet; where the chronic NOAEC is 1000 mg/kg-diet 
17 

Table 13. Amphibian/Reptile Acute Dose-based RQ values for Foliar Application to Potatoes for 

Cyromazine 

Dose-based RQs 

(Dose-based EEC/adjusted LD50) 

Amphibian/Reptile Acute RQs for Small, Medium, and Large Species (grams) 

2 20 

200 

Short Grass 0.00 0.00 0.00 

Tall Grass 0.00 0.00 0.00 

Broadleaf plants/sm insects 0.00 0.00 0.00 

Fruits/pods/seeds/lg insects 0.00 0.00 0.00 

Herbivore mammals 0.14 0.06 0.02 

Insectivore mammals 0.01 0.00 0.00 

Terrestrial phase amphibian 0.00 0.00 0.00 

Table 14. Amphibian/Reptile Dietary based Acute and Chronic RQ values for Foliar Application to 

Potatoes for Cyromazine 

Dietary-based RQs 

(Dietary-based EEC/LC50 or NOAEC) 

RQs 

Acute Chronic 

Short Grass 0.02 1.39 

Tall Grass 0.01 0.64 

Broadleaf plants/sm Insects 0.01 0.78 

Fruits/pods/seeds/lg insects 0.00 0.09 

Herbivore mammals 0.01 1.07 

Insectivore mammals 0.00 0.07 

Terrestrial phase amphibian 0.00 0.02 

Using these revised input values, for all uses except for potato, there are no acute listed or 

non-listed avian or mammalian LOC exceedances or avian or mammalian chronic LOC 

exceedances. For potatoes, there are no LOC exceedances for mammals, but the acute listed 

LOC was exceeded for small birds consuming short grass (RQ = 0.10). Also, the avian 

chronic LOC was exceeded for birds consuming short grass (RQ=1.39). Additionally, using 

the revised foliar dissipation half-life and the T-HERPs model with the default input 

parameters, there are no LOC exceedances for the foliar uses, except for potatoes. For the 

potato use, the acute listed LOC is exceeded for terrestrial-phase amphibians and reptiles 

consuming herbivorous mammals, and the chronic LOC is exceeded for terrestrial-phase 

amphibians and reptiles consuming short grass or herbivorous mammals. However, as THERPs has specific input parameters regarding diet and reptile and amphibian diets are 

expected to vary between species, this conclusion may not apply across all species. 

According to the data compiled by the Biological and Economic Analysis Division (BEAD) 

(D387940), regarding use of cyromazine, it appears that the average single foliar application 

rate for many crops is similar to the maximum single application rate on the label (reported 

average rate is 0.1 lb a.i./A, whereas the maximum label rate is 0.125 lb a.i./A). However, 
18 

where the label allows for a maximum of 6 applications, based on the compiled data from 

BEAD, it appears that the number of applications range from 1-2 with up to 3 for onions. 

Use data were not available for foliar use on potatoes. In the preliminary assessment, there 

are LOC exceedances for birds for the potato use. Based on the available BEAD data for the 

other foliar uses, the actual single application rate for potatoes may be similar to the 

maximum label rate (0.249 lb a.i./A), however, the number of applications actually applied 

may be lower than the label maximum number of applications allowed (up to 3 applications). 

A reduction to two applications for potatoes would reduce the acute avian RQ below the 

LOC and a reduction to only one application per year would reduce the chronic avian RQ 

below the LOC. The foliar dissipation half-life would need to be 3 days or less for the RQs 

to be below the LOC, and the available data do not support this value. 

Based on the usage data in Table 2 in the preliminary risk assessment, potatoes are not listed. 

This may suggest that the use of cyromazine on potatoes may be limited in amount applied. 

Figure 2 in the preliminary risk assessment illustrates that the geographical areas with higher 

cyromazine use are in California, southern Texas and Florida and part of New York. Based 

on available information, Florida produces less than 2% of the annual potato supply, but onethird of the winter/spring crop1

. Other information states that potato cultivation in New 

York accounts for 1.7% of the U.S. production with potatoes planted across several places in 

the state2. Other information reported that in 2011, 36,900, 36,400, 19,100 and 16,500 acres 

were planted in California, Florida, Texas and New York, respectively3. 

When modeling the exposure scenario for the potato foliar uses, the EECs (short grass) are 

greater than the avian NOAEC for a period of about 2 weeks for which the EECs do drop 

below the NOAEC for a short period prior to the next and final application (Figure 1). The 

EECs are not greater than the reported LOAEC of 300 mg/kg for birds. As stated in the 

preliminary assessment, the avian study that was used in this assessment to calculate RQs 

was not designed to evaluate how long the parental birds must be consuming dietary-items 

containing the chemical before effects on reproduction are observed. These studies are 

designed to allow the birds to consume treated feed for many weeks to allow time for 

equilibrium of the chemical within the bird and for the potential maternal transfer of the 

chemical to the eggs. As previously stated in the preliminary risk assessment, information 

suggests that cyromazine should equilibrate relatively quickly within an animal. Based on a 

metabolism study in poultry in which the birds were fed cyromazine-treated feed daily (at the 

maximum labeled rate), cyromazine is excreted primarily as parent at concentrations 

essentially equivalent to or greater than the concentration in the feed. Once cyromazine was 

removed from the feed, the cyromazine concentrations in the excreta were below detection 

limits by Day 3 of depuration (MRID 44759202). 

 

1 http://www.ipmcenters.org/CropProfiles/docs/FLpotatoes.pdf (access January 17, 2013) 

2 http://www.ipmcenters.org/CropProfiles/docs/nypotatoes.pdf (accessed January 17, 2013) 3 http://usda01.library.cornell.edu/usda/current/Pota/Pota-09-20-2012.pdf (accessed January 17, 2013) 
19 

Figure 1. Terrestrial EECs and Chronic Avian NOAEC value (figure generated 

in T-REX) 

In conclusion, the use of the revised foliar dissipation half-life and chronic mammalian twogeneration reproduction NOAEL resulted in RQ values that were less than the LOC for all 

foliar uses except for potatoes. Use data for potatoes, which could allow for further 

refinement of this use, is not available. Therefore, based on the RQs, there still is uncertainty 

in the potential for direct effects to small listed birds consuming short grass and from chronic 

direct effects to birds consuming short grass. A reduction in the number of applications from 

a maximum of 3, as per the label, to only one would reduce the avian RQ values below the 

LOC. 

 

11. Syngenta Crop Protection Comment: The seeding rate for treated onion seeds 

should be 2 -4 lb seed/A based on available data. 

EFED Response: While the risk estimation was conducted using the default seeding rate of 

75 lb seed/A, a characterization of the onion seed treatment use was provided using 4 lb 

seed/A which is the upper limit expressed by Syngenta. When using a seeding rate of 4 lb 

seed/A, and an application rate of 4.95 lb a.i./100 lb seed, the acute RQs are not exceeded 

based on the LD50/ft2

 method (method #2 in the assessment and TREX outputs) (RQs = 0.08 

for birds and 0.06 for mammals). However, when assessing acute and chronic exposure on a 

dietary basis (the number of seeds necessary to exceed the LOC), this evaluation is 

independent of seeding rate in the field and therefore, the acute and chronic RQs still exceed 

the LOC for both birds and mammals. The application rate to the seeds would need to be 

0.045 lb a.i. /100 lb seed to be below the acute listed avian LOC and would need to be 0.0075 
20 

lb a.i./100 lb seed to be below the avian chronic LOC. The currently labeled rate is 4.95 lb 

a.i./100 lb seed. 

In the preliminary risk assessment, an effort was undertaken to determine the number of 

seeds a bird or mammal would need to consume to exceed either the listed or non-listed 

LOC. A seeding rate of 4 lb seed/A was used in this exercise; additionally, the available data 

suggested that the number of onion seeds in a pound ranged from 100,000 to 130,000. Upon 

review of the data, the information provided in Table 27 in the preliminary risk assessment 

was not very clear, therefore, the data are re-presented below in Table 15. Based on the 

labeled seed treatment application rate and available number of seeds in a pound, a small bird 

would need to consume 11-14 seeds to achieve the acute listed LOC (1/10th LD50), whereas a 

small mammal would need to consume 15 - 20 seeds to achieve the acute listed LOC. 

Similarly, a small bird or mammal would need to consume 55-71 or 77-100 seeds to achieve 

the acute non-listed LOC (1/2 LD50). In using a seeding rate of 4 lb seed/A, a small bird 

would need to glean all seeds planted in one square feet to achieve the acute listed LOC 

(1/10th LD50) or six square feet to achieve the acute non-listed LOC (1/2 LD50) (Table 16). 

The area necessary to achieve the acute LOC for medium birds and mammals is 8 or 6 square 

feet, respectively, and is 75 ft2 or greater for large birds and mammals. The gleaning area 

necessary to achieve the acute non-listed LOC for small birds and mammals is 6 and 16-17 

ft2

, respectively. These values assume that all planted seeds are available for consumption 

and are consumed by one bird within the necessary area (sufficient competition for food may 

decrease exposure). However, based on the analysis, it appears that there is still potential 

exposure and potential direct effects to small, and potentially medium, birds and mammals 

from acute exposure to cyromazine treated onion seeds. 

Table 15. Number of Cyromazine Treated Onion Seeds Consumed by Birds and Mammals 

Necessary to Reach the Non-listed and Listed Level of Concerns 

Bird Mammal Number of seeds to reach the 

LOC of 0.5 or 0.1 

(100,000 seed/lb seed) 

Number of seeds 

to reach the LOC 

of 0.5 or 0.1 

(130,000 seeds/lb 

Weight of assessed animal (kg) 0.02 0.015 seed) 

Adjusted LD50, mg/kg-bw 

(based on 20 or 15g bird or mammal) 1229 2305 0.225 mg a.i/seed (based on 4.95 lb a.i./100 lb seed) 0.173 mg ai/seed 

mg a.i. needed to achieve the LD50 for 

animal of assessed weight 

24.581 66.891 bird mammal bird mammal 

mg a.i. needed to achieve the LOC of 

0.5 (1/2 LD50) for animal of assessed 

weight 

12.291 33.445 55 77 71 100 

mg a.i. needed to achieve the LOC of 

0.1 (1/10th LD50) for animal of 

assessed weight 

2.458 6.689 11 15 14 20 

 
21 

Table 16. Number of Square Feet Gleaned of Cyromazine Treated Onion Seeds by Birds and 

Mammals Necessary to Reach the Non-listed and Listed Level of Concerns 

4 lb seed/A 

seeding rate

100,000 seeds per lb seed 130,000 seeds per lb seed 

bird mammal bird mammal Animal Size Class 

Area in sq feet necessary to reach LOC 

LOC 0.5 

(non-listed) 6 17 6 16 Small 

LOC 0.1 (20g, bird; 15 g mammal) 

(listed) 1 2 1 2 

LOC 0.5 39 31 38 30 Medium 

LOC 0.1 8 6 8 6 (100g bird; 35 g mammal) 

LOC 0.5 546 385 532 376 Large 

LOC0.1 109 77 107 75 (1000g bird & mammal) 

12. Syngenta Crop Protection Comment, Section 2, Pg. 69, Lines 1-12: Cyromazine is 

a systemic insecticide and complete coverage of vegetation is not required to maintain 

efficacy. Based on calculations using ASAE medium to coarse droplet size and a 

toxicity value of 0.033 lb a.i./A (dicot, soybean, seedling emergence) or 0.268 lb a.i./A 

(monocot, corn, seedling emergence), the spray drift EECs overlap the toxicity values 

by 36.1 ft or less. For vegetative vigor toxicity values, the overlap is <20 ft for both 

monocots or dicots. Based on these calculations, effects to non-target plants would be 

spatially limited; additionally, cyromazine is used extensively as a seed treatment and 

effects to plants in the field are not expected. 

EFED Response: In the preliminary risk assessment, as droplet size is not specified on 

the labels, spray drift EECs were calculated using AgDrift (v2.01), using the default 

droplet size, fine to medium, for aerial and then using the user specified droplet size of 

fine to medium/coarse for ground. However, in the EFED guidance memo on modeling 

offsite deposition of pesticides via spray drift, the default droplet size for ground 

application should be very fine to fine (USEPA 2013). Therefore, the offsite 

deposition rates were recalculated using the defined default values (Table 17). For 

monocots, the overlap between EECs and toxicity values was four feet or less and was 

72 feet or less for dicots. In the preliminary assessment, EFED did recognize based on 

the analyses, that except for dicots exposed from aerial application to potatoes, any 

effect is anticipated to be spatially limited. 
22 

Table 17 Spray Drift (Terrestrial) Assessment for Terrestrial Plant Species 

No. of application 

and app. rate 

(lb a.i/.A) 

distance from 

edge of field 

% of 

application 

rate 

EEC 

(lb a.i./A) 

Dicot 

(SE)a

Monocot 

(SE)b

Monocot 

(VV)c

Spray 

Method

Terrestrial plants inhabiting areas off-site of application area 

1 @ 0.249 

(potatoes) 0 feet 0.5 0.12 3.6 0.44 0.92 

Aerial 

1 @ 0.249 73 feet 0.13 0.032 0.97 0.12 0.25 

1 @ 0.249 0 feet 1 0.27 8.2 1 2.1 

Ground 1 @ 0.249 7 feet 0.35 0.088 2.7 0.33 0.68 

1 @ 0.249 20 feet 0.05 0.0325 0.98 0.12 0.25 

a Based on reported phytotoxicity in dicot species, Glycine max, at 0.033 lb a.i./A in the seedling emergence test. 

Value represent ratio of dry area EEC by reported value for phytotoxicity 

a Based on reported phytotoxicity in monocot species, Zea mays, at 0.27 lb a.i./A in the seedling emergence test. 

Value represent ratio of dry area EEC by reported value for phytotoxicity 

Based on reported phytotoxicity in monocot species, Zea mays, at 0.13 lb a.i./A in the vegetative vigor test. Value 

represent ratio of dry area EEC by reported value for phytotoxicity 

Drift values based on: aerial - droplet size ASAE Fine to medium, ground – droplet size ASAE very fine to fine, 

high boom, 90th percentile 

13. Syngenta Crop Protection Comment, Section 5, Pg. 72, Lines 11-13: The 

assumption that all the cyromazine is removed while planting treated seeds is overly 

conservative. Suggest that this exposure estimate be refined for increased 

environmental relevance. 

EFED Response: EFED agrees that this assumption is potentially conservative, but data 

regarding potential loss of cyromazine during seeding are not available. However, it is 

anticipated that exposure of cyromazine to non-target organisms through the labeled uses 

(foliar application, seed treatment, soil amendment) should be sufficient to adequately assess 

potential risk to non-target organisms. Exposure to abraded dust may be of concern to 

terrestrial invertebrates through direct contact to the dust. Cyromazine toxicity in 

invertebrates appears to be targeted to the larval stages of the organism, and therefore, direct 

contact to the dust would likely be due to a settling of the dust after it becomes airborne 

during the abrasion process. This type of contact could also be expected from direct foliar 

application and exposure via spray drift, or from soil amendment with cyromazine-treated 

manure. Therefore, the labeled uses of cyromazine are anticipated to adequately capture 

potential exposure routes to terrestrial invertebrates during the vulnerable windows of 

exposure. 

 
23 

Literature Cited 

Brady, Donald. 2013. Guidance on Modeling Offsite Deposition of Pesticides via Spray Drift for 

Ecological and Drinking Water Assessments. US EPA/OCSPP Memorandum. 

U.S. Environmental Protection Agency (USEPA). 2013. Preliminary Ecological Risk Assessment 

for the Registration Review of Cyromazine. January 24, 2013. Docket No. 

http://www.regulations.gov/#!docketDetail;D=EPA-HQ-OPP-2006-0108 

U.S. Environmental Protection Agency (USEPA). 2013. Guidance on Modeling Offsite Deposition 

of Pesticides via Spray Drift for Ecological and Drinking Water Assessments. Environmental Fate 

and Effects Division. Office of Pesticide Programs. December 20, 2013. 

 
24 

Appendix 1. GEENEC, PRZM-EXAMS, T-REX, T-HERPS, AgDrift outputs. 

 

GENEEC MODEL OUTPUT 

 RUN No. 1 FOR cyromazine ON Lima bean * INPUT VALUES * 

 -------------------------------------------------------------------- 

 RATE (#/AC) No.APPS & SOIL SOLUBIL APPL TYPE NO-SPRAY INCORP 

 ONE(MULT) INTERVAL Kd (PPM ) (%DRIFT) ZONE(FT) (IN) 

 -------------------------------------------------------------------- 

 .125( .692) 6 7 2.3******* AERL_B( 13.0) .0 .0 

 FIELD AND STANDARD POND HALFLIFE VALUES (DAYS) 

 -------------------------------------------------------------------- 

 METABOLIC DAYS UNTIL HYDROLYSIS PHOTOLYSIS METABOLIC COMBINED 

 (FIELD) RAIN/RUNOFF (POND) (POND-EFF) (POND) (POND) 

 -------------------------------------------------------------------- 

 147.30 2 N/A .00- .00 294.60 294.60 

 GENERIC EECs (IN MICROGRAMS/LITER (PPB)) Version 2.0 Aug 1, 2001 

 -------------------------------------------------------------------- 

 PEAK MAX 4 DAY MAX 21 DAY MAX 60 DAY MAX 90 DAY 

 GEEC AVG GEEC AVG GEEC AVG GEEC AVG GEEC 

 -------------------------------------------------------------------- 

 32.44 32.35 31.79 30.55 29.66 

 RUN No. 2 FOR Leafy Veg ON Leafy Veg * INPUT VALUES * 

 -------------------------------------------------------------------- 

 RATE (#/AC) No.APPS & SOIL SOLUBIL APPL TYPE NO-SPRAY INCORP 

 ONE(MULT) INTERVAL Kd (PPM ) (%DRIFT) ZONE(FT) (IN) 

 -------------------------------------------------------------------- 

 .125( .586) 5 7 2.3******* AERL_B( 13.0) .0 .0 

 FIELD AND STANDARD POND HALFLIFE VALUES (DAYS) 

 -------------------------------------------------------------------- 

 METABOLIC DAYS UNTIL HYDROLYSIS PHOTOLYSIS METABOLIC COMBINED 

 (FIELD) RAIN/RUNOFF (POND) (POND-EFF) (POND) (POND) 

 -------------------------------------------------------------------- 

 147.30 2 N/A .00- .00 294.60 294.60 

 GENERIC EECs (IN MICROGRAMS/LITER (PPB)) Version 2.0 Aug 1, 2001 

 -------------------------------------------------------------------- 

 PEAK MAX 4 DAY MAX 21 DAY MAX 60 DAY MAX 90 DAY 

 GEEC AVG GEEC AVG GEEC AVG GEEC AVG GEEC 

 -------------------------------------------------------------------- 

 27.42 27.34 26.86 25.82 25.07 

 RUN No. 3 FOR cyromazine ON potato * INPUT VALUES * 

 -------------------------------------------------------------------- 

 RATE (#/AC) No.APPS & SOIL SOLUBIL APPL TYPE NO-SPRAY INCORP 

 ONE(MULT) INTERVAL Kd (PPM ) (%DRIFT) ZONE(FT) (IN) 

 -------------------------------------------------------------------- 

 .249( .723) 3 7 2.3******* AERL_B( 13.0) .0 .0 
25 

 FIELD AND STANDARD POND HALFLIFE VALUES (DAYS) 

 -------------------------------------------------------------------- 

 METABOLIC DAYS UNTIL HYDROLYSIS PHOTOLYSIS METABOLIC COMBINED 

 (FIELD) RAIN/RUNOFF (POND) (POND-EFF) (POND) (POND) 

 -------------------------------------------------------------------- 

 147.30 2 N/A .00- .00 294.60 294.60 

 GENERIC EECs (IN MICROGRAMS/LITER (PPB)) Version 2.0 Aug 1, 2001 

 -------------------------------------------------------------------- 

 PEAK MAX 4 DAY MAX 21 DAY MAX 60 DAY MAX 90 DAY 

 GEEC AVG GEEC AVG GEEC AVG GEEC AVG GEEC 

 -------------------------------------------------------------------- 

 33.72 33.62 33.04 31.75 30.82 

 APPENDIX 

PRZM MODEL OUTPUT 

 MePotato; 8/05/02 

"Maine Potato, MLRA 146, Modified from MEPOTIR1.inp from F Drive; Metfile: 

W14607.dvf (old: Met146.met), 

*** Record 3: 

 0.8 0.36 0 12.5 1 3 

*** Record 6 -- ERFLAG 

 4 

*** Record 7: 

 0.28 1.34 1 10 3 6 356.8 

*** Record 8 

 1 

*** Record 9 

 1 0.1 60 40 3 89 86 89 0 30 

*** Record 9a-e 

 1 28 

0106 1606 0107 1607 0108 1608 0109 1609 0110 0510 1610 0111 1611 0112 1612 0101 

.788 .645 .400 .310 .173 .056 .053 .135 .267 .511 .544 .570 .586 .591 .593 .593 

.014 .014 .014 .014 .014 .014 .014 .014 .014 .014 .014 .014 .014 .014 .014 .014 

 86 86 86 86 86 86 86 86 86 89 89 89 89 89 89 89 

1601 0102 1602 0103 1603 0104 1604 0105 0505 1505 1605 2005 

.592 .591 .590 .589 .594 .604 .623 .640 .631 .758 .762 .801 

.014 .014 .014 .014 .014 .014 .014 .014 .014 .014 .014 .014 

 89 89 89 89 89 89 89 89 89 89 89 89 

*** Record 10 -- NCPDS, the number of cropping periods 

 30 

*** Record 11 

 010661 011061 051061 1 

 010662 011062 051062 1 

 010663 011063 051063 1 

 010664 011064 051064 1 

 010665 011065 051065 1 

 010666 011066 051066 1 

 010667 011067 051067 1 

 010668 011068 051068 1 

 010669 011069 051069 1 

 010670 011070 051070 1 

 010671 011071 051071 1 

 010672 011072 051072 1 

 010673 011073 051073 1 
26 

 010674 011074 051074 1 

 010675 011075 051075 1 

 010676 011076 051076 1 

 010677 011077 051077 1 

 010678 011078 051078 1 

 010679 011079 051079 1 

 010680 011080 051080 1 

 010681 011081 051081 1 

 010682 011082 051082 1 

 010683 011083 051083 1 

 010684 011084 051084 1 

 010685 011085 051085 1 

 010686 011086 051086 1 

 010687 011087 051087 1 

 010688 011088 051088 1 

 010689 011089 051089 1 

 010690 011090 051090 1 

*** Record 12 -- PTITLE 

Cyromazine - 3 applications @ 0.279 0.279 0.279 kg/ha 

*** Record 13 

 90 1 0 0 

*** Record 15 -- PSTNAM 

Cyromazine 

*** Record 16 

 010661 0 2 0.0 0.279 .95 .05 

 080661 0 2 0.0 0.279 .95 .05 

 150661 0 2 0.0 0.279 .95 .05 

 010662 0 2 0.0 0.279 .95 .05 

 080662 0 2 0.0 0.279 .95 .05 

 150662 0 2 0.0 0.279 .95 .05 

 010663 0 2 0.0 0.279 .95 .05 

 080663 0 2 0.0 0.279 .95 .05 

 150663 0 2 0.0 0.279 .95 .05 

 010664 0 2 0.0 0.279 .95 .05 

 080664 0 2 0.0 0.279 .95 .05 

 150664 0 2 0.0 0.279 .95 .05 

 010665 0 2 0.0 0.279 .95 .05 

 080665 0 2 0.0 0.279 .95 .05 

 150665 0 2 0.0 0.279 .95 .05 

 010666 0 2 0.0 0.279 .95 .05 

 080666 0 2 0.0 0.279 .95 .05 

 150666 0 2 0.0 0.279 .95 .05 

 010667 0 2 0.0 0.279 .95 .05 

 080667 0 2 0.0 0.279 .95 .05 

 150667 0 2 0.0 0.279 .95 .05 

 010668 0 2 0.0 0.279 .95 .05 

 080668 0 2 0.0 0.279 .95 .05 

 150668 0 2 0.0 0.279 .95 .05 

 010669 0 2 0.0 0.279 .95 .05 

 080669 0 2 0.0 0.279 .95 .05 

 150669 0 2 0.0 0.279 .95 .05 

 010670 0 2 0.0 0.279 .95 .05 

 080670 0 2 0.0 0.279 .95 .05 

 150670 0 2 0.0 0.279 .95 .05 

 010671 0 2 0.0 0.279 .95 .05 

 080671 0 2 0.0 0.279 .95 .05 

 150671 0 2 0.0 0.279 .95 .05 

 010672 0 2 0.0 0.279 .95 .05 

 080672 0 2 0.0 0.279 .95 .05 

 150672 0 2 0.0 0.279 .95 .05 

 010673 0 2 0.0 0.279 .95 .05 

 080673 0 2 0.0 0.279 .95 .05 

 150673 0 2 0.0 0.279 .95 .05 
27 

 010674 0 2 0.0 0.279 .95 .05 

 080674 0 2 0.0 0.279 .95 .05 

 150674 0 2 0.0 0.279 .95 .05 

 010675 0 2 0.0 0.279 .95 .05 

 080675 0 2 0.0 0.279 .95 .05 

 150675 0 2 0.0 0.279 .95 .05 

 010676 0 2 0.0 0.279 .95 .05 

 080676 0 2 0.0 0.279 .95 .05 

 150676 0 2 0.0 0.279 .95 .05 

 010677 0 2 0.0 0.279 .95 .05 

 080677 0 2 0.0 0.279 .95 .05 

 150677 0 2 0.0 0.279 .95 .05 

 010678 0 2 0.0 0.279 .95 .05 

 080678 0 2 0.0 0.279 .95 .05 

 150678 0 2 0.0 0.279 .95 .05 

 010679 0 2 0.0 0.279 .95 .05 

 080679 0 2 0.0 0.279 .95 .05 

 150679 0 2 0.0 0.279 .95 .05 

 010680 0 2 0.0 0.279 .95 .05 

 080680 0 2 0.0 0.279 .95 .05 

 150680 0 2 0.0 0.279 .95 .05 

 010681 0 2 0.0 0.279 .95 .05 

 080681 0 2 0.0 0.279 .95 .05 

 150681 0 2 0.0 0.279 .95 .05 

 010682 0 2 0.0 0.279 .95 .05 

 080682 0 2 0.0 0.279 .95 .05 

 150682 0 2 0.0 0.279 .95 .05 

 010683 0 2 0.0 0.279 .95 .05 

 080683 0 2 0.0 0.279 .95 .05 

 150683 0 2 0.0 0.279 .95 .05 

 010684 0 2 0.0 0.279 .95 .05 

 080684 0 2 0.0 0.279 .95 .05 

 150684 0 2 0.0 0.279 .95 .05 

 010685 0 2 0.0 0.279 .95 .05 

 080685 0 2 0.0 0.279 .95 .05 

 150685 0 2 0.0 0.279 .95 .05 

 010686 0 2 0.0 0.279 .95 .05 

 080686 0 2 0.0 0.279 .95 .05 

 150686 0 2 0.0 0.279 .95 .05 

 010687 0 2 0.0 0.279 .95 .05 

 080687 0 2 0.0 0.279 .95 .05 

 150687 0 2 0.0 0.279 .95 .05 

 010688 0 2 0.0 0.279 .95 .05 

 080688 0 2 0.0 0.279 .95 .05 

 150688 0 2 0.0 0.279 .95 .05 

 010689 0 2 0.0 0.279 .95 .05 

 080689 0 2 0.0 0.279 .95 .05 

 150689 0 2 0.0 0.279 .95 .05 

 010690 0 2 0.0 0.279 .95 .05 

 080690 0 2 0.0 0.279 .95 .05 

 150690 0 2 0.0 0.279 .95 .05 

*** Record 17 

 0 1 0 

*** Record 18 

 0 0 0.5 

*** Record 19 -- STITLE 

"Conant Silt Loam MLRA M-146, Aroostook County, ME" 

*** Record 20 

 100 0 0 0 0 0 0 0 0 0 

*** Record 26 

 0 0 0 

*** Record 33 

 4 
28 

 1 10 1.25 0.341 0 0 0 

 0.0047060.004706 0 

 0.1 0.341 0.121 4.64 2.25 

 2 16 1.25 0.341 0 0 0 

 0.0047060.004706 0 

 4 0.341 0.121 4.64 2.25 

 3 64 1.4 0.266 0 0 0 

 0.0047060.004706 0 

 4 0.266 0.116 0.174 2.25 

 4 10 1.6 0.261 0 0 0 

 0.0047060.004706 0 

 5 0.261 0.111 0.116 2.25 

***Record 40 

 0 

 YEAR 10 YEAR 10 YEAR 10 1 

 1 

 1 ----- 

 7 YEAR 

 PRCP TCUM 0 0 

 RUNF TCUM 0 0 

 INFL TCUM 1 1 

 ESLS TCUM 0 0 1.0E3 

 RFLX TCUM 0 0 1.0E5 

 EFLX TCUM 0 0 1.0E5 

 RZFX TCUM 0 0 1.0E5 

PRZM-EXAMS WATER COLUMN CONCENTRATION

 ME Potato 

 WATER COLUMN DISSOLVED CONCENTRATION (PPB) 

 YEAR PEAK 96 HOUR 21 DAY 60 DAY 90 DAY YEARLY 

 ---- ---- ------- ------ ------ ------ ------ 

 1961 3.041 3.023 2.939 2.845 2.685 1.263 

 1962 4.468 4.390 4.192 3.884 3.719 2.485 

 1963 4.458 4.437 4.325 4.057 3.877 2.713 

 1964 4.584 4.550 4.412 4.200 4.089 2.855 

 1965 4.687 4.670 4.589 4.448 4.392 3.383 

 1966 5.372 5.347 5.274 5.222 5.148 3.860 

 1967 5.850 5.797 5.588 5.149 4.975 3.784 

 1968 5.004 4.954 4.866 4.715 4.594 3.461 

 1969 5.484 5.459 5.348 5.067 4.814 3.370 

 1970 4.628 4.598 4.486 4.344 4.262 2.851 

 1971 3.853 3.837 3.780 3.650 3.580 2.678 

 1972 7.069 7.024 6.847 6.651 6.323 4.067 

 1973 5.328 5.282 5.074 4.686 4.516 3.635 

 1974 5.101 5.076 4.994 4.802 4.610 3.468 

 1975 5.644 5.604 5.551 5.415 5.330 4.208 

 1976 7.370 7.264 7.006 6.535 6.112 4.317 

 1977 7.367 7.297 7.063 6.704 6.206 4.070 

 1978 5.873 5.802 5.554 5.228 5.089 3.931 

 1979 4.643 4.618 4.575 4.485 4.323 3.343 

 1980 4.972 4.932 4.853 4.725 4.592 3.365 

 1981 5.355 5.323 5.257 4.889 4.277 2.819 

 1982 4.732 4.675 4.516 4.215 4.047 2.647 

 1983 6.123 6.050 5.818 5.346 5.090 3.368 

 1984 6.740 6.687 6.476 6.152 5.959 4.249 

 1985 5.593 5.576 5.500 5.400 5.281 4.691 

 1986 4.718 4.703 4.634 4.454 4.278 3.449 
29 

 1987 5.348 5.319 5.239 5.080 4.934 3.734 

 1988 4.928 4.908 4.825 4.657 4.495 3.662 

 1989 5.096 5.070 4.987 4.826 4.631 3.584 

 1990 8.977 8.888 8.666 8.051 7.696 4.554 

 SORTED FOR PLOTTING 

 ------ --- -------- 

 PROB PEAK 96 HOUR 21 DAY 60 DAY 90 DAY YEARLY 

 ---- ---- ------- ------ ------ ------ ------ 

 .032 8.977 8.888 8.666 8.051 7.696 4.691 

 .065 7.370 7.297 7.063 6.704 6.323 4.554 

 .097 7.367 7.264 7.006 6.651 6.206 4.317 

 .129 7.069 7.024 6.847 6.535 6.112 4.249 

 .161 6.740 6.687 6.476 6.152 5.959 4.208 

 .194 6.123 6.050 5.818 5.415 5.330 4.070 

 .226 5.873 5.802 5.588 5.400 5.281 4.067 

 .258 5.850 5.797 5.554 5.346 5.148 3.931 

 .290 5.644 5.604 5.551 5.228 5.090 3.860 

 .323 5.593 5.576 5.500 5.222 5.089 3.784 

 .355 5.484 5.459 5.348 5.149 4.975 3.734 

 .387 5.372 5.347 5.274 5.080 4.934 3.662 

 .419 5.355 5.323 5.257 5.067 4.814 3.635 

 .452 5.348 5.319 5.239 4.889 4.631 3.584 

 .484 5.328 5.282 5.074 4.826 4.610 3.468 

 .516 5.101 5.076 4.994 4.802 4.594 3.461 

 .548 5.096 5.070 4.987 4.725 4.592 3.449 

 .581 5.004 4.954 4.866 4.715 4.516 3.383 

 .613 4.972 4.932 4.853 4.686 4.495 3.370 

 .645 4.928 4.908 4.825 4.657 4.392 3.368 

 .677 4.732 4.703 4.634 4.485 4.323 3.365 

 .710 4.718 4.675 4.589 4.454 4.278 3.343 

 .742 4.687 4.670 4.575 4.448 4.277 2.855 

 .774 4.643 4.618 4.516 4.344 4.262 2.851 

 .806 4.628 4.598 4.486 4.215 4.089 2.819 

 .839 4.584 4.550 4.412 4.200 4.047 2.713 

 .871 4.468 4.437 4.325 4.057 3.877 2.678 

 .903 4.458 4.390 4.192 3.884 3.719 2.647 

 .935 3.853 3.837 3.780 3.650 3.580 2.485 

 .968 3.041 3.023 2.939 2.845 2.685 1.263 

 1/10 7.337 7.240 6.990 6.639 6.197 4.310 

 MEAN OF ANNUAL VALUES = 3.462 

 STANDARD DEVIATION OF ANNUAL VALUES = .715 

 UPPER 90% CONFIDENCE LIMIT ON MEAN = 3.656 

PRZM-EXAMS PORE WATER CONCENTRATION

 ME Potato 

 PORE WATER DISSOLVED CONCENTRATION (PPB) 

 YEAR PEAK 96 HOUR 21 DAY 60 DAY 90 DAY YEARLY 

 ---- ---- ------- ------ ------ ------ ------ 
30 

 1961 1.910 1.910 1.906 1.888 1.873 .898 

 1962 3.023 3.023 3.021 3.009 2.984 2.195 

 1963 3.130 3.130 3.128 3.111 3.088 2.594 

 1964 3.382 3.382 3.377 3.344 3.309 2.612 

 1965 3.681 3.681 3.680 3.667 3.647 3.136 

 1966 4.349 4.349 4.344 4.315 4.277 3.599 

 1967 4.174 4.174 4.166 4.118 4.063 3.624 

 1968 3.876 3.875 3.870 3.839 3.806 3.267 

 1969 3.994 3.994 3.991 3.951 3.892 3.367 

 1970 3.465 3.465 3.458 3.411 3.349 2.776 

 1971 2.959 2.959 2.956 2.944 2.931 2.477 

 1972 5.390 5.390 5.381 5.322 5.250 3.934 

 1973 4.267 4.255 4.206 4.099 4.002 3.572 

 1974 3.765 3.765 3.765 3.760 3.755 3.289 

 1975 4.614 4.614 4.613 4.606 4.592 3.847 

 1976 5.091 5.091 5.081 5.023 4.965 4.345 

 1977 5.036 5.035 5.023 4.957 4.888 3.964 

 1978 4.260 4.260 4.258 4.249 4.236 3.728 

 1979 4.131 4.127 4.096 3.984 3.878 3.392 

 1980 3.786 3.786 3.784 3.774 3.758 3.077 

 1981 3.750 3.749 3.721 3.576 3.432 2.978 

 1982 3.346 3.346 3.344 3.329 3.303 2.374 

 1983 4.106 4.106 4.101 4.072 4.033 3.081 

 1984 4.937 4.937 4.937 4.931 4.919 3.904 

 1985 4.915 4.912 4.901 4.871 4.836 4.545 

 1986 4.341 4.330 4.267 4.064 3.909 3.481 

 1987 4.093 4.092 4.091 4.085 4.070 3.438 

 1988 3.886 3.877 3.841 3.763 3.751 3.534 

 1989 3.882 3.881 3.874 3.842 3.814 3.431 

 1990 5.949 5.948 5.942 5.872 5.773 4.255 

 SORTED FOR PLOTTING 

 ------ --- -------- 

 PROB PEAK 96 HOUR 21 DAY 60 DAY 90 DAY YEARLY 

 ---- ---- ------- ------ ------ ------ ------ 

 .032 5.949 5.948 5.942 5.872 5.773 4.545 

 .065 5.390 5.390 5.381 5.322 5.250 4.345 

 .097 5.091 5.091 5.081 5.023 4.965 4.255 

 .129 5.036 5.035 5.023 4.957 4.919 3.964 

 .161 4.937 4.937 4.937 4.931 4.888 3.934 

 .194 4.915 4.912 4.901 4.871 4.836 3.904 

 .226 4.614 4.614 4.613 4.606 4.592 3.847 

 .258 4.349 4.349 4.344 4.315 4.277 3.728 

 .290 4.341 4.330 4.267 4.249 4.236 3.624 

 .323 4.267 4.260 4.258 4.118 4.070 3.599 

 .355 4.260 4.255 4.206 4.099 4.063 3.572 

 .387 4.174 4.174 4.166 4.085 4.033 3.534 

 .419 4.131 4.127 4.101 4.072 4.002 3.481 

 .452 4.106 4.106 4.096 4.064 3.909 3.438 

 .484 4.093 4.092 4.091 3.984 3.892 3.431 

 .516 3.994 3.994 3.991 3.951 3.878 3.392 

 .548 3.886 3.881 3.874 3.842 3.814 3.367 

 .581 3.882 3.877 3.870 3.839 3.806 3.289 

 .613 3.876 3.875 3.841 3.774 3.758 3.267 

 .645 3.786 3.786 3.784 3.763 3.755 3.136 

 .677 3.765 3.765 3.765 3.760 3.751 3.081 

 .710 3.750 3.749 3.721 3.667 3.647 3.077 

 .742 3.681 3.681 3.680 3.576 3.432 2.978 

 .774 3.465 3.465 3.458 3.411 3.349 2.776 

 .806 3.382 3.382 3.377 3.344 3.309 2.612 

 .839 3.346 3.346 3.344 3.329 3.303 2.594 
31 

 .871 3.130 3.130 3.128 3.111 3.088 2.477 

 .903 3.023 3.023 3.021 3.009 2.984 2.374 

 .935 2.959 2.959 2.956 2.944 2.931 2.195 

 .968 1.910 1.910 1.906 1.888 1.873 .898 

 1/10 5.086 5.085 5.075 5.016 4.960 4.226

PRZM-EXAMS SEDIMENT CONCENTRATION

 

 ME Potato 

 BENTHIC SEDIMENT CONCENTRATION (ug/kg) 

 YEAR PEAK 96 HOUR 21 DAY 60 DAY 90 DAY YEARLY 

 ---- ---- ------- ------ ------ ------ ------ 

 1961 5.004 5.004 4.993 4.947 4.908 2.354 

 1962 7.921 7.921 7.916 7.883 7.818 5.752 

 1963 8.201 8.201 8.194 8.152 8.090 6.796 

 1964 8.862 8.861 8.847 8.761 8.671 6.845 

 1965 9.645 9.645 9.642 9.609 9.555 8.215 

 1966 11.400 11.390 11.380 11.310 11.210 9.430 

 1967 10.940 10.940 10.910 10.790 10.640 9.494 

 1968 10.150 10.150 10.140 10.060 9.972 8.559 

 1969 10.460 10.460 10.460 10.350 10.200 8.822 

 1970 9.079 9.078 9.060 8.937 8.775 7.274 

 1971 7.752 7.752 7.746 7.712 7.678 6.489 

 1972 14.120 14.120 14.100 13.940 13.760 10.310 

 1973 11.180 11.150 11.020 10.740 10.480 9.358 

 1974 9.865 9.865 9.863 9.852 9.838 8.616 

 1975 12.090 12.090 12.090 12.070 12.030 10.080 

 1976 13.340 13.340 13.310 13.160 13.010 11.390 

 1977 13.190 13.190 13.160 12.990 12.810 10.380 

 1978 11.160 11.160 11.160 11.130 11.100 9.768 

 1979 10.820 10.810 10.730 10.440 10.160 8.887 

 1980 9.919 9.919 9.915 9.888 9.847 8.063 

 1981 9.825 9.822 9.750 9.369 8.992 7.803 

 1982 8.765 8.765 8.761 8.721 8.654 6.220 

 1983 10.760 10.760 10.750 10.670 10.570 8.072 

 1984 12.940 12.940 12.930 12.920 12.890 10.230 

 1985 12.880 12.870 12.840 12.760 12.670 11.910 

 1986 11.370 11.350 11.180 10.650 10.240 9.119 

 1987 10.720 10.720 10.720 10.700 10.660 9.008 

 1988 10.180 10.160 10.060 9.859 9.829 9.258 

 1989 10.170 10.170 10.150 10.070 9.993 8.989 

 1990 15.590 15.590 15.570 15.380 15.120 11.150 

 SORTED FOR PLOTTING 

 ------ --- -------- 

 PROB PEAK 96 HOUR 21 DAY 60 DAY 90 DAY YEARLY 

 ---- ---- ------- ------ ------ ------ ------ 

 .032 15.590 15.590 15.570 15.380 15.120 11.910 

 .065 14.120 14.120 14.100 13.940 13.760 11.390 

 .097 13.340 13.340 13.310 13.160 13.010 11.150 

 .129 13.190 13.190 13.160 12.990 12.890 10.380 

 .161 12.940 12.940 12.930 12.920 12.810 10.310 

 .194 12.880 12.870 12.840 12.760 12.670 10.230 

 .226 12.090 12.090 12.090 12.070 12.030 10.080 

 .258 11.400 11.390 11.380 11.310 11.210 9.768 
32 

 .290 11.370 11.350 11.180 11.130 11.100 9.494 

 .323 11.180 11.160 11.160 10.790 10.660 9.430 

 .355 11.160 11.150 11.020 10.740 10.640 9.358 

 .387 10.940 10.940 10.910 10.700 10.570 9.258 

 .419 10.820 10.810 10.750 10.670 10.480 9.119 

 .452 10.760 10.760 10.730 10.650 10.240 9.008 

 .484 10.720 10.720 10.720 10.440 10.200 8.989 

 .516 10.460 10.460 10.460 10.350 10.160 8.887 

 .548 10.180 10.170 10.150 10.070 9.993 8.822 

 .581 10.170 10.160 10.140 10.060 9.972 8.616 

 .613 10.150 10.150 10.060 9.888 9.847 8.559 

 .645 9.919 9.919 9.915 9.859 9.838 8.215 

 .677 9.865 9.865 9.863 9.852 9.829 8.072 

 .710 9.825 9.822 9.750 9.609 9.555 8.063 

 .742 9.645 9.645 9.642 9.369 8.992 7.803 

 .774 9.079 9.078 9.060 8.937 8.775 7.274 

 .806 8.862 8.861 8.847 8.761 8.671 6.845 

 .839 8.765 8.765 8.761 8.721 8.654 6.796 

 .871 8.201 8.201 8.194 8.152 8.090 6.489 

 .903 7.921 7.921 7.916 7.883 7.818 6.220 

 .935 7.752 7.752 7.746 7.712 7.678 5.752 

 .968 5.004 5.004 4.993 4.947 4.908 2.354 

 1/10 13.325 13.325 13.295 13.143 12.998 11.073 

 
33 

T-REX and T-HERPS MODEL OUTPUT

Acute and Chronic RQs are based on the Uppe

Kenaga Residues.

Chemical Name: The maximum single day residue estimation is

 Use both the acute and reproduction RQs.

 Formulation

Application Rate 0.249 lbs a.i./acre RQs reported as "0.00" in the RQ tables be

Half-life 7 days <0.01 in your assessment. This is due to ro

Application Interval 7 days figure issues in Excel.

Maximum # Apps./Year 3

Length of Simulation 1 year

Variable application rates? no

Bobwhite quail LD50 (mg/kg-bw) 1706.00

Bobwhite quail LC50 (mg/kg-diet) 0.00

Mallard duck NOAEL(mg/kg-bw) 0.00

Mallard duck NOAEC (mg/kg-diet) 75.00

2029.00

0.00

54.60

1000.00

Kenaga

Values

Short Grass 104.58

Tall Grass 47.93

Broadleaf plants 58.83

Fruits/pods/seeds 6.54

Arthropods 40.96

Avian Results Avian Body Ingestion (Fdry) Ingestion (Fwet) % body wgt FI

Class Weight (g) (g bw/day) (g/day) consumed (kg-diet/day)

Small 20 5 23 114 2.28E-02

Mid 100 13 65 65 6.49E-02

Large 1000 58 291 29 2.91E-01

20 5 5 25 5.06E-03

Granivores 100 13 14 14 1.44E-02

1000 58 65 6 6.46E-02

Avian Body Adjusted LD50

Weight (g) (mg/kg-bw)

20 1229.05

100 1564.65

1000 2210.12

small mid large

20 100 1000

Short Grass 119.11 67.92 30.41

Tall Grass 54.59 31.13 13.94

Broadleaf plants 67.00 38.20 17.10

Fruits/pods 7.44 4.24 1.90

Arthropods 46.65 26.60 11.91

Seeds 1.65 0.94 0.42

Dose-based EECs 

(mg/kg-bw) 

Avian Classes and Body Weights (grams)

 Upper Bound Kenaga Residues For RQ Calculation

Dietary-based EECs (ppm)

NOAEL (mg/kg-bw)

NOAEC (mg/kg-diet)

Mammals

LD50 (mg/kg-bw)

LC50 (mg/kg-diet)

cyromazine

potatoes

0

Avian

Endpoints

Questions? 

Comments? 

Click here
34 

20 100 1000

Short Grass 0.10 0.04 0.01

Tall Grass 0.04 0.02 0.01

Broadleaf plants 0.05 0.02 0.01

Fruits/pods 0.01 0.00 0.00

Arthropods 0.04 0.02 0.01

Seeds 0.00 0.00 0.00

Dietary-based RQs 

Acute Chronic

Short Grass #DIV/0! 1.39

Tall Grass #DIV/0! 0.64

Broadleaf plants #DIV/0! 0.78

Fruits/pods/seeds #DIV/0! 0.09

Arthropods #DIV/0! 0.55

Note: To provide risk management with the maximum possible information,

it is recommended that both the dose-based and concentration-based 

RQs be calculated when data are available

cyromazine potatoes Upper bound Kenaga Residues

Mammalian Results

Mammalian Body Ingestion (Fdry) Ingestion (Fwet) % body wgt FI

Class Weight (g bwt/day) (g/day) consumed (kg-diet/day)

15 3 14 95 1.43E-02

Herbivores/ 35 5 23 66 2.31E-02

insectivores 1000 31 153 15 1.53E-01

15 3 3 21 3.18E-03

Grainvores 35 5 5 15 5.13E-03

1000 31 34 3 3.40E-02

Mammalian Body Adjusted Adjusted

Class Weight LD50 NOAEL

15 2305.39 120.00

Herbivores/ 35 1865.31 97.09

insectivores 1000 806.80 42.00

15 2305.39 120.00

Granivores 35 1865.31 97.09

1000 806.80 42.00

15 35 1000

Short Grass 99.71 68.91 15.98

Tall Grass 45.70 31.58 7.32

Broadleaf plants 56.09 38.76 8.99

Fruits/pods 6.23 4.31 1.00

Arthropods 39.05 26.99 6.26

Seeds 1.38 0.96 0.22

15 grams 35 grams 1000 grams

Acute Chronic Acute Chronic Acute Chronic

Short Grass 0.04 0.83 0.04 0.71 0.02 0.38

Tall Grass 0.02 0.38 0.02 0.33 0.01 0.17

Broadleaf plants 0.02 0.47 0.02 0.40 0.01 0.21

Fruits/pods 0.00 0.05 0.00 0.04 0.00 0.02

Arthropods 0.02 0.33 0.01 0.28 0.01 0.15

Seeds 0.00 0.01 0.00 0.01 0.00 0.01

Acute Chronic

Short Grass #DIV/0! 0.10

Tall Grass #DIV/0! 0.05

Broadleaf plants #DIV/0! 0.06

Fruits/pods/seeds #DIV/0! 0.01

Arthropods #DIV/0! 0.04

Note: To provide risk management with the maximum possible information,

it is recommended that both the dose-based and concentration-based 

RQs be calculated when data are available

Dietary-based RQs 

(Dietary-based EEC/LC50 or 

NOAEC)

Mammal RQs

Medium mammal Large mammal Dose-based RQs 

(Dose-based EEC/LD50 or 

Small mammal

Dose-Based EECs 

(mg/kg-bw)

(grams)

Mammalian Classes and Body weight

Dose-based RQs 

(Dose-based EEC/adjusted LD50)

RQs

Avian Acute RQs

Size Class (grams)
35 

Acute and Chronic RQs are based on the Upper Bound 

Kenaga Residues.

Chemical Name: The maximum single day residue estimation is used for 

 Use both the acute and reproduction RQs.

 Formulation

Application Rate 0.249 lbs a.i./acre RQs reported as "0.00" in the RQ tables below should be note

Half-life 7 days <0.01 in your assessment. This is due to rounding and signifi

Application Interval 7 days figure issues in Excel.

Maximum # Apps./Year 3

Length of Simulation 1 year

Bobwhite quail LD50 (mg/kg-bw) 1706.00

Bobwhite quail LC50 (mg/kg-diet) 5373.00

Bobwhite quail NOAEL(mg/kg-bw) 0.00

Mallard duck NOAEC (mg/kg-diet) 75.00

Kenaga

Values

Short Grass 104.58

Tall Grass 47.93

Broadleaf plants/sm Insects 58.83

Fruits/pods/seeds/lg insects 6.54

Small herbivore mammals 234.93

Medium herbivore mammal 80.17

Large herbivore mammal 27.35

Small insectivore mammals 14.68

Medium Insectivorous mammal 5.01

Large Insectivorous mammal 1.71

Small terrestrial phase amphibians 3.23

Medium terrestrial phase amphibians 1.85

Large terrestrial phase amphibians 1.05

Terrestrial Herpetofauna Results

Weight Body Ingestion (Fdry) Ingestion (Fwet) % body wgt FI

Class Weight (g) (g bw/day) (g/day) consumed (kg-diet/day)

Small 2 0.022 0.1 5.6 1.11E-04

Mid 20 0.132 0.7 3.3 6.59E-04

Large 200 0.781 3.9 2.0 3.90E-03

Body Adjusted LD50

Weight (g) (mg/kg-bw)

2 1706.00

20 1706.00

200 1706.00

small (g) mid (g) large (g)

2 20 200

Short Grass 5.81 3.44 2.04

Tall Grass 2.66 1.58 0.94

Broadleaf plants/sm Insects 3.27 1.94 1.15

Fruits/pods/seeds/lg insects 0.36 0.22 0.13

Herbivore mammals 246.78 99.17 39.85

Insectivore mammals 15.42 6.20 2.49

Reptile/Terrestrial phase amphibian 3.39 2.28 1.54

2 20 200

Short Grass 0.00 0.00 0.00

Tall Grass 0.00 0.00 0.00

Broadleaf plants/sm insects 0.00 0.00 0.00

Fruits/pods/seeds/lg insects 0.00 0.00 0.00

Herbivore mammals 0.14 0.06 0.02

Insectivore mammals 0.01 0.00 0.00

Terrestrial phase amphibian 0.00 0.00 0.00

Acute Chronic

Short Grass 0.02 1.39

Tall Grass 0.01 0.64

Broadleaf plants/sm Insects 0.01 0.78

Fruits/pods/seeds/lg insects 0.00 0.09

potatoes

0

Herpetofaunal Size Classes and Body Weights

RQs

 Upper Bound Kenaga Residues For RQ Calculation

Dietary-based EECs (ppm)

cyromazine

Endpoints

Avian

Dietary-based RQs (Dietarybased EEC/LC50 or NOAEC)

Amphibian/Reptile Acute RQs for Small, Medium, and 

Dose-based RQs (Dose- Large Species (grams)

based EEC/adjusted LD50)

Dose-based EECs 

(mg/kg-bw) 

Questions? 

Comments? 

Click here
36 

2 20 200

Short Grass 0.00 0.00 0.00

Tall Grass 0.00 0.00 0.00

Broadleaf plants/sm insects 0.00 0.00 0.00

Fruits/pods/seeds/lg insects 0.00 0.00 0.00

Herbivore mammals 0.14 0.06 0.02

Insectivore mammals 0.01 0.00 0.00

Terrestrial phase amphibian 0.00 0.00 0.00

Acute Chronic

Short Grass 0.02 1.39

Tall Grass 0.01 0.64

Broadleaf plants/sm Insects 0.01 0.78

Fruits/pods/seeds/lg insects 0.00 0.09

Herbivore mammals 0.01 1.07

Insectivore mammals 0.00 0.07

Terrestrial phase amphibian 0.00 0.02

Dietary-based RQs (Dietary- RQs

based EEC/LC50 or NOAEC)

Amphibian/Reptile Acute RQs for Small, Medium, and 

Dose-based RQs (Dose- Large Species (grams)

based EEC/adjusted LD50)
37 

AgDrift example output.