2

ISKBC Comment: Section 4.a. Ecological Risk Assessment, first paragraph, "EFED evaluated 

cyazofamid's potential risks to non-target and endangered species for aquatic and terrestrial 

organisms (including plants) (DP Barcodes D319107+ and D356880+). In addition, in the 2012 

assessment EFED evaluated chronic risk to birds and risk to terrestrial plants, based upon newly 

reviewed data (DP Barcode D396387).

We have not received the DERs for any of the studies that were apparently reviewed and 

referenced here. Please provide the 2012 EFED assessment (DP Barcode D396387) and DERs 

for the submitted studies.

EFED Response:

EFED has supplied the requested 2012 EFED assessment (D396387) and DERs listed in the 

table below. 

DP Barcode MRID Study Type Executive Summary from DER

D366145 47716308 850.2300

Colinus 

virginianus

The one-generation reproductive toxicity of IKF-916 Technical 

(cyazofamid) to 24 pairs per level (48 for the control) of 27-week old 

Norther bobwhite quail (Colinus virginianus) was assessed over ca.

22 weeks. IKD-916 Technical was administered to the birds in the 

diet at nominal concentrations of 0 (control), 28, 84, 167, or 1000 

mg/kg diet (not adjusted for purity). Mean measured concentrations 

were <7.14 (<LOD, control), 28.3, 86.1, 170, and 1020 mg ai/kg diet, 

respectively.

There were no treatment-related effects observed on any adult 

parameter. Egg production was the only reproductive parameter 

evaluated and this endpoint was reduced in a dose-dependent manner 

17 to 25%, relative to control; the reviewer’s analysis detected a 

statistically significant difference (p=0.035) at only the highest 

treatment level. Given this reduction, the reviewer determined the 

NOAEC to be 170 mg ai/kg diet.

This study is scientifically sound and does satisfy the guideline 

requirement for a Northern bobwhite (Colinus virginianus) 

reproductive study.

D366145 47716309 850.4100

Seedling 

emergence

The effect of IKF-916 400SC (ai cyazofamid) on the seedling 

emergence of monocot (corn, Zea mays; oat, Avena sativa; onion, 

Allium cepa; and ryegrass) and dicot (cucumber, Cucumis sativa; 

lettuce, Lactuna sativa; carrot, Daucus carota;soybean, Glycine max;

radish, Raphanus sativus; cabbage, Brassica oleracea; and tomato, 

Lycopersicon esculentum) crops were studied at nominal 

concentrations of 0 (negative control) and 1.56 lbs ai/A (equivalent to 

4.65 lbs formulation/A).

The growth medium used in the seedling emergence test was a 

mixture of collected silt loam and masonry sand that was classified as 
3

a loam soil (pH 7.3,% organic matter 1.5%). After 14 days, the

number of plants emerged was recorded and taken for measuring dry 

weight and height. 

Negative control emergence ranged from 80 to 100% for all species 

tested, and treatment group emergence ranged from 86% to 100%. 

There was promotion of growth in seedling height for carrot, oat and 

radish, while inhibitions for all other species ranged from 1 to 6%. 

There was promotion of growth in dry weight for cucumber, corn, oat, 

and radish, while cabbage and ryegrass did not experience inhibitions 

in dry weight. Lettuce, onion, soybean and tomato had inhibitions 

ranging from 2% to 11% and carrot had an inhibition in dry weight of 

19%.

No phytoxicity or abnormality was reported for any species. 

The most sensitive monocot and dicot species could not be 

determined due to the lack of a statistically significant effect on any 

of the plants. The overall NOAEC and EC25 values for all species 

tested were 1.56 and >1.56 ai/A. respectively, which is equivalent to 

4.65 and >4.65 lbs formulation/A, respectively.

This toxicity study is classified as acceptable and satisfied the 

guideline requirement for a Tier I terrestrial plant toxicity study.

D366145 47716310 850.4150

Vegetative 

Vigor

The effect of IKD-916 400SC (ai cyazofamid) on the vegetative vigor 

of monocot (corn, Zea mays; oat, Avena sativa; onion, Allium cepa; 

and ryegrass) and dicot (cucumber, Cucumis sativa; lettuce, Lactuna 

sativa; carrot, Daucus carota; soybean, Glycine max; radish, 

Raphanus sativus; cabbage, Brassica oleracea; and tomato, 

Lycopersicon esculentum) crops were studies at nominal 

concentrations of 0 (negative control) and 1.56 lbs ai/A. Corn, 

cucumber, lettuce, oat, onion and soybean were actually treated with 

1.56 lbs cyazofamid/A, while cabbage, carrot, radish, ryegrass and 

tomato were treated with 1.57 lbs cyazofamid/A (equivalent to 4.65 

and 4.68 lbs formulation/A, respectively)

The growth medium used in the seedling emergence test was a 

mixture of collected silt loan and masonry sand that was classified as 

a loam soil (pH 7.3, % organic matter 1.5%). After 14 days all plants 

were recorded and taken for measuring dry weight and height.

Height and dry weight per plant were unaffected by the test material.

No phytotoxicity or abnormality was reported for any species.
4

The most sensitive monocot and dicot species could not be 

determined due to the lack of a statistically significant effect on any 

of the plants. The overall NOAEC and EC25 values for corn, 

cucumber, lettuce, oat, onion and soybean were 1.56 and >1.56 ai/A 

respectively, which is equivalent to 4.65 and >4.65 lbs formulation/A, 

respectively. The overall NOAEC and EC25 values for cabbage, 

carrot, radish, ryegrass and tomato were 1.57 and >1.57 lbs ai/A 

respectively, which is equivalent to 4.68 and 4.65 lbs formulation/A.

This study is classified as acceptable and satisfied the guideline 

requirement for a Tier I Terrestrial Plant Vegetative Vigor toxicity 

study.

ISKBC Comment: Page 18, 6 Receptors c. Ecological Incidents: According to the Agency's 

records, as well as ISK Biosciences Corporation's records, there have been no ecological 

incidents associated with cyazofamid. Thus this fact provides some degree of certainty that the 

models being used that suggest potential concerns with non-target organisms can be considered 

very conservative.

EFED Response:

EFED is aware that there have been no ecological incidents associated with cyazofamid and 

have thus reported accordingly in the Problem Formulation. At the conclusion of the above 

mentioned paragraph which details the databases used in incident compilation, the Problem 

Formulation states, “EIIS, AIMS, and Aggregates Incident Database were run on November 

12, 2014 and did not return any incidents.” Incident occurrence is used in risk characterization 

to demonstrate a complete exposure pathway, however the absence of reported incidents does 

not indicate that there is an absence of exposure. The absence of reported incidents does not 

change the potential concerns for non-target organisms nor does it indicate whether or not 

EFED models used to assess risk to non-target organisms are conservative. 

ISKBC Comment: Page 19, 8. Analysis Plan, a. Stressors of Concern, The stressors of concern 

are listed as cyazofamid and degradation products (CCIM, CCIM-AM and CTCA). "Submitted 

studies on mammals indicate that CCIM toxicity to mammals is more toxic than cyazofamid; 

this increased toxicity triggers concern on an acute basis. CCIM-AM and CTCA have similar 

toxicity to the parent.

This conclusion was based on one acute oral study of CCIM. HED has also identified these 

degradation products in the "Cyazofamid Human Health Scoping Document in Support of 

Registration Review" as residues of concern in water. Only parent and CCIM were of concern 

in plant residues. In that same document, HED stated they did not have any concerns to the

population from exposure to parent or its degradation products. They further stated in the 

review table on page 24 that the results of the special metabolism studies suggest that "IKF-916 

is stable in stomach contents" of rats and "CCIM could be produced in rats following IKF-916 

entering the blood compartment but not necessarily in the stomach compartment." Thus, the
5

ecological concern for the formation of CCIM from exposure to consuming cyazofamid from 

plant tissues should be greatly reduced.

EFED Response:

All soil metabolism studies demonstrate the formation of CCIM from the parent in high 

concentrations; formation is expected to occur in plant tissue as well. Toxicity data 

demonstrates CCIM to have a higher toxicity than the parent. Additionally, CCIM is highly 

persistent in water (stable to hydrolysis) and moderate in soils, ~0.9 days to ~2.9 days. There 

is the potential for non-target terrestrial organisms to come into contact with CCIM on the field, 

therefore the ecological concern for CCIM remains. 

The section quoted in the above comment from ISKBC, "CCIM could be produced in rats 

following IKF-916 entering the blood compartment but not necessarily in the stomach 

compartment,” is referring to the likelihood of cyazofamid degrading to CCIM while in the 

stomach compartment of the organism. While this particular route of exposure is not likely, 

CCIM presents other route of exposure as well. There is the potential for CCIM to be present 

in plant tissues consumed by mammals and avian species, thus exposure cannot be assumed to 

be reduced. 

ISKBC Comment: Page 25, Section 11. Preliminary Identification of Data Gaps, a. 

Environmental Fate Table 4, (also mentioned on page 2 - Data Gaps, Environmental Chemistry 

Methods/Independent Laboratory Validations); OCSPP 850.6100: Analytical methods in soil, 

water, and sediment are required.

Methods for water and soil were submitted (MRID Nos. 45409021 & 45409037) and this 

review suggests that they are still in review, thus, we have not received any DERs to which we 

can respond to comments that suggest the data is not acceptable. No new studies should be 

required until we have an opportunity to review and correct any deficiencies in these studies. 

Please provide the DERs for these studies. We have a study in sediment that was submitted to 

and accepted by Canada and we will submit that study to the Agency to address the method for 

sediment. Thus we request a waiver from conducting any further studies for this requirement 

until the Agency completes their review of the submitted studies.

EFED Response: As part of the screen EFED conducted of these ECM/ILV’s, a number of issues 

were observed, which were named in the Problem Formulation. It was further indicated that 

the studies were in review. EFED completed the screen of the studies and found the studies to 

be unreviewable since the ECMs were submitted in the same document than the ILVs. A 

separate memorandum will be issued for these studies. In order to consider the studies, separate 

ECMs and ILVs should be submitted. Other issues noted in the studies should also be addressed 

at the time the studies are resubmitted.

ISKBC Comment: Page 27, Section 11. Preliminary Identification of Data Gaps, b. Effects, Table 

6 - Data Needs, fish toxicity, invertebrate life cycle, saltwater invertebrates (OCSPP 850.1075; 

1300; 1350)
6

Estuarine/marine fish Toxicity; The DER stated, "This study is scientifically sound, but it is 

classified as Supplemental, because terminal fish weights ranged lower than the initial fish 

weight that is recommended by USEPA. The 96-hour LC50 was >167 μg a.i./L, the highest 

level tested and above the water solubility level, which categorizes IKF-916 Technical as highly 

toxic to sheepshead minnow on an acute toxicity basis. The ECOSAR model estimates the 

LC50 in fish to be 2.551 mg/L, which is over 100 fold safer than the study value. Since this was 

an acute study, repeating the study will most likely not change the LC50 value for this 

requirement due to solubility limits and we request a waiver from conducting a replacement 

study for this requirement.

Invertebrate life cycle; Two studies were submitted for this requirement. In the first study, 

(MRID # 45409136) the author reported the NOEC as 0.039 mg a.i./L with the LOEC being

>0.11 mg a.i./L. The Agency's DER stated, "The study is scientifically sound, but it does not 

fulfill the USEPA requirements for a chronic freshwater invertebrate toxicity study 

(Subdivision E, §72-4b) because dry weights were not measured. As a result, this study is 

classified as INVALID." In the second study (MRID 46702708), the DER classified the study 

as supplemental "based on the conclusion that the NOAEC for dry body weight was below the 

lowest rate tested (0.0087 mg ai/L)". A response to the DER was submitted on 3/26/09 (MRID 

47716307) in which the laboratory conducting the study addressed EPA's comments and 

provided justification that the NOAEC for dry body weight was 0.02 mg a.i./L, which is similar 

to the first study. Additionally, based on the well-defined concentration response provided in 

this study, it is unlikely that a repeat test will define the NOAEC any more precisely than 

provided by this value. We have not seen a DER for this response and we note that it is not 

mentioned in the document. Thus, we request a waiver from conducting any further studies for 

this requirement until the Agency completes their review of the submitted response.

EFED Response:

The DER for MRID 45409131 on the acute toxicity of cyazofamid to Sheepshead minnow 

(Cyprinodon variegatus) classified the study as supplemental. The terminal fish weights for 

the study were 0.46 g, and ranged lower than the minimum initial fish weight that is 

recommended by USEPA (0.5 g). Individual fish weights were not provided, so the variation 

and fish weight and thus the severity of this deviation cannot be adequately determined. 

Because fish weight can affect fish response to pesticides, this deviation impacted the 

acceptability of the study. The study saw 15% mortality in the highest treatment level, which 

is equivalent to the solubility limit. A study waiver may be considered for the study gap if the 

individual fish weight data for this study is submitted, reviewed, and the variation in the fish 

weight is determined to not be severe enough to be considered a study deficiency. 

Two studies were available for the daphnid full life cycle guideline requirement: MRID 

45409136 was classified as invalid based on lack of measurement of dry weights and MRID 

46702708 was classified as supplemental because the NOAEC for dry weights was below the 

lowest rate tested (0.0087 mg ai/L). A follow up to MRID 46702708 was submitted under 

MRID 47716307 in March 2009; EFED responded to this follow up in August 2010 under 

D366145. EFED stated the following in the memorandum:
7

“This study was classified previously as SUPPLEMENTAL because a valid NOAEC 

could not be establish as well as a question regarding a drop in toxicant 

concentrations due to a problem with the toxicant delivery pump. The NOAEC was 

determined to be <0.0087 mg ai/L. In the response, it was suggested that pooled 

control data could be used for NOAEC determination as well as substituting an EC10 

for a NOAEC per the updated OECD Algal Test Guideline #201. The response 

suggested that the EC10 was 0.019 mg ai/L with 95% confidence limits of 0.0085 to 

0.41 mg ai/L.”

Additionally, the DER for this response has been provided. Daphnid full life cycle is still 

considered to be a data gap.

ISKBC Comment: Page 28, Section 11. Preliminary Identification of Data Gaps, b. Effects, Table 

6 - Data Needs, Cyanobacteria (OCSPP 850.4550)

A Cyanobacteria study (MRID 46209402) was submitted to the Agency which was listed as 

invalid. Three other algae studies were also listed as invalid. The NOAEC was determined to 

be >0.25 mg a.i./L, the highest level tested. The ECOSAR model estimates the NOAEC in 

green algae to be 0.186 mg/L, which is very similar the study value. Since we have not received 

DERs for any of these studies, replacement studies should not be required until we have 

received the DERs and have had a chance to provide additional information to correct any 

deficiencies. Please provide the DERs for the submitted studies so that we can respond to the 

reviews. Thus we request a waiver from conducting any further studies for this requirement at 

this time.

EFED Response:

EFED has provided the DERs for the following MRIDs, the executive summaries have been 

summarized in the table below. Of the submitted studies, three were classified as supplemental, 

one was classified as invalid and one was classified as acceptable.

DP Barcode MRID Study Type Executive Summary from DER

D304897 46209402 850.4500 

Skeletonema 

costatum

In a 96-hour acute toxicity study, culture of Skeletonema costatum

were exposed to Cyazofamid under static conditions at nominal 

concentrations 0 (negative and solvent controls), 0.010, 0.026, 

0.064, 0.16, 0.40, and 1.0 ppm ai. The time weighted mean 

measured concentrations were <0.0021-0.0025 (<LOQ, negative 

and solvent controls), 0.0036, 0.0088, 0.020, 0.045, 0.087 and 0.10 

ppm ai. At the 0-hour analytical determination, only the two lowest 

treatment concentrations produced recoveries >70% of nominal. 

Furthermore, the three highest nominal concentrations exceeded the 

limit of water solubility (0.108 mg/L) for Cyazofamid Technical. 

All concentrations of test material declined substantially over the 

course of the study, presumably due to the photo degradation of 

cyazofamid and to the presence of algae. 
8

The toxicity study is scientifically sound but it does not satisfy the 

US EPA Guideline Subdivision J, 123-2 because of the uncertainty 

associated with the actual test concentrations that algae were 

exposed to, and thus, the inability to derive accurate toxicity values. 

As a result, the study is classified as supplemental.

D283446 45409143 850.4500

Selenastrum 

capricornutum

In a 96-hour acute toxicity study, cultures of Selenastrum 

capricornutum were exposed to Cyazofamid under static conditions. 

Nominal concentrations were 5, 10, 22, 46 and 100 μg/L. The mean 

measured concentrations for the two highest treatment 

concentrations ranged below 70% of nominal over the 96-hour study 

and measurement of the lowest treatment concentration was 

inaccurate. Cell density, biomass, and growth rate were significantly 

affected by treatment with cyazofamid. Cell growth inhibition 

ranged from 18.6% in the nominal 5 μg/L treatment group to 72.1 % 

in the nominal 100 μg/L treatment group. 

The study is not scientifically sound and does not satisfy the US EPA 

Guideline Subdivision J, 123-2 for an aquatic nonvascular plant 

study. The initial 24 hours of the test were conducted in darkness 

because the test material was considered photosensitive, impurities 

(detected during analytical determination) were introduced during 

sample pretreatment and measurement of the 4.8 μg/L solution 

concentrations were inaccurate and, therefore, calculation by 

extrapolation. As a result, a reliable toxicity value could not be 

estimated from this study and it is classified as invalid.

D304897 46258213 850.4500

Selenastrum 

capricornutum

In a 96-hour acute toxicity study, cultures of Selenastrum 

capricornutum were exposed to Cyazofamid (IKF-916 400SC with 

organosilicone adjuvant) under static conditions at nominal 

concentrations of 0 (negative control), 4.6, 40, 22, 46, 100, 220, 460 

and 1000 ppb ai (corresponded to 12.8, 28, 61, 128, 280, 610, 1280, 

and 2800 ppb). Because the measured concentrations declined 

>70% of nominal over the course of the study, the measured 0-hour 

concentrations were used to compute the toxicity values; the 0-hour 

concentrations were 4.0, 10, 22, 43, 98, 221, 458 and 1000 ppb ai. 

During the test, continuous lighting was provided from 24 to 96 

hours, but no lighting was used in the first 24 hours. The 96-hour 

cell density percent inhibitions were 11, 28, 25, 38, 59, 58, 66 and 

68% in the treatment groups respectively. The biomass percent 

inhibitions were 9, 21, 24, 36, 61, 67, and 19% in the treatment 

groups respectively; The growth rate (24 to 96 hours) percent 

inhibitions were 3.8, 7.9, 7.1, 9.6, 16.9, 19.6, 19.0 and 19.0% in the 

treatment groups respectively. Biomass was the most sensitive 

parameter, with an EC50 of 100 ppm ai; the NOAEC for biomass 

(and all other endpoints) was 4.0 ppb ai. The study is scientifically 

sound and satisfies the US EPA Guideline 123-2 for an aquatic 

nonvascular study. The study is classified as core.
9

D304987 46209403 850.4550

Anabaena 

flos-aquae

In a 96-hour acute toxicity study, cultures of Anabaena flos-aquae 

were exposed to Cyazofamid under static conditions at nominal 

concentrations 0 (negative and solvent controls), 0.010, 0.026, 

0.064, 0.16, 0.40, and 1.0 ppm ai. The time weight mean measured 

concentrations were <0.0021-0.0022 (<LOQ, negative and solvent 

controls), 0.0049. 0.011, 0.027, 0.050, 0.16, and 0.25 ppm ai. At the 

0–hour analytical determination, the three lowest treatment 

concentrations produced recoveries >7-% of nominal. The three 

highest nominal concentration exceeded the limit of water solubility 

(0.108 mg/L) for cyazofamid technical All concentrations of test 

material declined substantially over the course of the study, 

presumably due to the photodegradation of cyazofamid and to the 

presence of the algae. 

The 96-hour cell density percent inhibitions were 32, 20, 14, 12, 25 

and 37% in the treatment groups respectively. The 72-hour biomass 

(areas under the growth curve) percent inhibitions were 55, 25, 1, 

17, 26, and 22% in the treatment groups respectively. The 72-hour 

growth rate percent inhibitions were -5, -6, -6, -7, 32 and 7% in the 

treatment groups respectively. No significant inhibitions were 

observed for cell densities, growth rates or biomass compared to the 

pooled control. 

This toxicity study was scientifically sound but does not satisfy the 

US EPA Guideline Subdivision J, 123-2 because of the uncertainty 

associated with the actual test concentrations that algae were 

exposed to and thus the inability to derive accurate toxicity values. 

However, no significant effects were noted up to the limit of 

solubility. As a result, this study is classified as supplemental. 

D304897 46209404 850.4500

Navicula 

pelliculosa

In a 96 hour acute toxicity study, cultures of Navicula pelliculosa

were exposed to cyazofamid under static conditions at nominal 

concentrations 0 (negative and solvent controls), 0.010, 0.026, 

0.064, 0.16, 0.40 and 1.0 ppm ai. The time-weighted mean measured 

concentrations were <0.0019-0.0028 (<LOQ, negative and solvent 

controls), 0.0039, 0.0075, 0.014, 0.019, 0.0073 and 0.12 ppm ai. At 

the 0-hour analytical determination, only the two lowest treatment 

concentrations produced recoveries >70% of nominal. Furthermore, 

the three highest nominal concentrations exceeded the limit of water 

solubility (0.108 mg/L) for cyazofamid technical. All 

concentrations of test material declined substantially over the course 

of the study, presumable due to the photodegradation of cyazofamid 

and to the presence of the algae. 

The 96-hour cell density percent inhibitions were -39, -38, -71, -118, 

-110, and -6% in the treatment groups respectively. The 72-hour 

biomass (areas under the growth curve) percent inhibitions were 17, 
10

-27, -27, -47, -24 and -19% in the treatment groups respectively. No 

significant inhibitions were observed for the cell densities or growth 

rates, compared to the pooled control. The biomass, areas under the 

growth curve, was significantly reduced in the 0.073 and 0.12 ppm 

ai treatment groups compared to the pooled control. 

This toxicity study is not scientifically sound and does not satisfy the 

US EPA Guideline Subdivision J, 123-2 because of the uncertainty 

associated with the actual test concentrations that algae were 

exposed to and thus the inability to derive accurate toxicity values. 

However, there were no effects and as a result, this study is classified 

as supplemental. 

ISKBC Comment: Pages 29 & 30, Section 11. Preliminary Identification of Data Gaps, b. Effects,

Table 7 - Data Needs, Bee toxicity (6 special studies)

The need for both Tier I and Tier II tests following the new pollinator guidance is stated, but 

the guidance document (Guidance for Assessing Pesticide Risks to Bees, June 19, 2014) 

specifically outlines a tiered approach that clearly delineates a progression from Tier I to Tier 

II tests, based on the results from the Tier I tests and calculation of the resulting risk (Figure 1, 

Tiered Approach for Assessing Risk to Honey Bees from Foliar Spray Applications, page 9 of 

guidance document). It seems premature to recommend conducting both Tier I and Tier II tests 

simultaneously, when the need for Tier II studies may be obviated, particularly since 

cyazofamid has been shown to be non-toxic to bees. The more appropriate course of action,

would appear to be requiring the necessary Tier I tests only, followed by an evaluation 

according to the new guidelines before requiring the higher tier testing, in this case, the Tier II 

field and semi-field honeybee and pollen/nectar studies. Since cyazofamid has been shown to 

be non-toxic to bees and since it is not a systemic product and thus will not move within the 

plant, we request waivers for all of the Tier II studies.

EFED Response:

The EFED pollinator guidance outlines the process for completing study requirements and 

explains the requirement of the Tier II studies will be pending based on the results of acceptable 

Tier I tests.

ISKBC Comment: Pages 31, Section 11. Preliminary Identification of Data Gaps, b. Effects, 

Table 8 - Data Needs, invertebrate chronic and fish ELS (OCSPP 850.1300; 1400)

We have an octanol/water partition coefficient study resulting in a low Log Pow of 1.04 and an 

aerobic soil metabolism study for CTCA that shows that CTCA is extensively mineralized in 

soils with DT50 values at 20°C of 21 to 33 days and DT90 values of 69-109 days. Both of these 

studies were required by Canada and were accepted by PMRA. We will submit them to the 

Agency for review. Since the acute LC50 toxicity value for fish (rainbow trout) showed that 

CTCA was more than 100 times less toxic then parent, (>92.2 ppm vs. 0.56 ppm) these two 

studies should not be necessary. In addition, using this information in ECOSAR, the resulting 
11

freshwater chronic NOEC value for invertebrates (0.184 ppm) is at least 10 times less toxic 

than parent. The resulting ECOSAR NOEC value for fish (0.237 ppm) is in the same range as 

seen in the studies conducted using the parent. Thus, we request a waiver from conducting these 

two studies for on CTCA.

EFED Response: The submitted studies are still in review with EFED thus we cannot specifically 

comment at this time.