2

Response to Syngenta’s Comments on the Simazine Problem Formulation –

Questions Related to Ecological Data  

Syngenta Comment: The acute freshwater invertebrate study with Daphnia, MRID 45088221, 

is a non-GLP study with numerous experimental and methodological issues that detract from the 

validity of the study. These include: 1) organisms were added to test chambers before the test 

material chemical was administered, 2) test concentrations were not reported nor analytically 

confirmed, 3) raw data were not reported and a concentration-dependent effect relationship was 

not described nor could one be confirmed, 4) control performance was not reported, and 5) 

statistics used to derive effect endpoints were not detailed. Similar data quality concerns also 

exist for the other aquatic invertebrate endpoints reported in MRID 45088221.... MRID 

46561305 was conducted with analytical confirmation and under GLP, and is the best available 

data providing a 48-hour EC50 = 100000 J.Lg a.i./L. Measurements of simazine in exposure 

water were 64 to 101% of nominal. Only 5% immobility was noted in the highest test 

concentration (100 mg/L). The findings of MRID 46561305 indicate no acute effects on aquatic 

invertebrates at concentrations at or above the solubility of simazine. 

EPA Response - EFED recognizes that there are deficiencies in the study as it compares to the 

draft guideline for an acute daphnid toxicity study; however, these do not surmount to an 

invalidation of this study. While GLP is considered as an important part of conducting a study, 

EFED routinely accepts non-GLP Guideline studies from registrants as part of registration 

packages and does not invalidate registrant submitted or open literature studies based on the GLP 

status. Additionally, the article discusses the endpoints in terms of a Tolerance Level, which the 

authors explain was estimated using a modified Litchfield Wilcoxon statistical method. EFED 

also acknowledges that there are studies available that resulted in less sensitive endpoints; 

however, the open literature data are considered when the results indicate a more sensitive 

endpoint than submitted by the registrant or other open literature derived endpoints. 

As previously noted in EFED’s response to comments from Syngenta on the Interim Reregistration Eligibility Decision, the acute freshwater invertebrate study submitted by Syngenta 

(MRID 46561305) has been categorized as invalid for the following reasons: 1) precipitate was 

observed at all treatment levels >3.2 mg/L indicating that the solvent (tetrahydrofuran [THF] and 

alkylphenol-polyglycolether) was not effective; 2) the study author did not demonstrate other 

means or techniques that could have been used to maximize simazine's dissolution in the test 

media under standard conditions (i.e., use of saturator columns, sonication, centrifugation, etc.); 

3) mean-measured concentrations provided by the study author are not representative of the 

bioavailable or dissolved fraction of simazine (i.e., mean-measured concentrations are total 

concentrations including both the dissolved and colloidal material; samples were not filtered); 4) 

the concentration of solvent used (1 ml/L) at the highest test concentration (100 mg/L) exceeds 

the 0.5 ml/L limit specified in EPA's Standard Evaluation Procedure for Acute Toxicity Tests 

with Freshwater Invertebrates (EPA-5401985-005); and 5) the solvents used (THF and 

alkylphenol-polyglycolether) are not included on the list of EPA-preferred solvents. 

Syngenta Comment: The relevance and accuracy of the ACR-derived NOAEC value of 40 ug 

a.i./L for Daphnia magna is questionable given the aforementioned inconsistency and data 
3

quality concerns associated with MRID 45088221 and should not be used for risk assessment. 

EPA (2010) did not identify any data quality issues with this study and in fact, selected the 

NOAEC (> 2,000 ug a.i./L) from that study to characterize chronic risk to aquatic invertebrates 

in their 2007 assessment of the effects of simazine on the California red-legged frog. In addition, 

Syngenta has identified a D. magna 21-d reproduction GLP-study performed with technical 

material (Rufli, H. 1989), the NOAEC based on immobilization and reproduction endpoints is 

140 ug a.i./L. 

EPA response – EFED will consider the scientific literature that Syngenta has identified prior to 

completing the risk assessment. The reported NOAEC that Syngenta has identified in Rufli 

(1989) is roughly 3 times greater than the estimate using the ACR approach in the problem 

formulation. Because no simazine-specific data on freshwater invertebrate taxa were available, 

the ACR calculations used in the simazine problem formulation used atrazine data from MRIDs 

45087413 and 00024377 with acute and chronic toxicity endpoints for D. magna of 3500 and 

140 μg a.i./L, respectively. These atrazine data are similar to propazine acute and chronic 

toxicity endpoints for D. magna of 5320 (MRID 44287305) and 47 μg a.i./L (MRID 44332760), 

respectively. Therefore, EFED believes that the estimated chronic daphnid endpoint of 40 ug/L 

for simazine is an appropriate estimation. Further consideration of the ACR approach for this 

endpoint will be made in light of the review of the Rufli (1989) report once it is submitted to the 

agency. 

Syngenta Comment: The estuarine/marine fish acute toxicity test using Seabream (Sparus 

aurata; E76270) is a non-GLP study and the lack of analytical confirmation of simazine in 

exposure media and absence of raw data considerably detracts from the overall quality of the 

study. The test material in Table 3 is also referred to as TGAI, whereas the study was conducted 

with the formulation Gesatop® GW, which is 90% simazine. Syngenta respectfully considers 

that the GLP study MRID 42503702 to be substantially more scientifically robust. This study 

was completed with sheepshead minnow and no mortalities or sublethal effects were observed at 

the highest test concentration (4300 ug a.i. /L). The 96-h LC50 value for MRID 42503702 was 

reported as > 4300 ug a.i./L. While the endpoint is non-definitive, Syngenta believes that data 

from MRID 42503702 are useful for future ecological risk assessments. Furthermore, Syngenta 

considers that the ACR value should be calculated based on data from MRID 42503702, rather 

than E76270; as such, the chronic endpoint should be reported as >642 ug a.i./L. 

EPA Response – This study and its corresponding text will be correctly referenced in the 

preliminary risk assessment to reflect the material used in the E76270 study was the 90% 

simazine formulation Gesatop® GW. The use of this study is consistent with EFED’s policy 

regarding open literature acceptability criteria. EPA’s review of MRID 42503702 does not result 

in endpoints that concur with the comment from Syngenta, but agrees that the study is useful for 

ecological risk assessments. Because the endpoints from MRID 42503702 are less sensitive than 

those reported in E76270, they will be considered for characterization purposes. Therefore, 

based on the available data, the ACR will continue to be based on the E76270 study results. 
4

Syngenta Comment: Syngenta respectfully considers that data from the GLP study MRID 

42662401 is far more scientifically robust than the Turbak et al. (1986) and should be used in the 

risk assessment. This study (MRID 42662401) was completed with Anabaena flos-aquae and the 

endpoint, based on abundance data, is 36 ug a.i./L. This endpoint (because it is the most sensitive 

algae endpoint) has previously been used in the EPA Endangered Species assessments for 

simazine (delta smelt and California red legged frog). However, effective concentrations (ECx) 

calculated based on growth rate are considered more robust than those based on standing crop 

(cell density and biomass) for a given time-point since growth rate is independent of exposure 

time (Erickson 2012). Syngenta posits that relative growth rate is a more appropriate measure 

than abundance for establishing effect concentrations for aquatic plants. Based on the 

aforementioned information and that relative growth rate is a more appropriate measure than 

abundance for establishing effect concentrations for aquatic plants, the appropriate EC50 values 

should be 114.9 ug a.i./L based on recalculation of relative growth data. 

EPA Response – EFED has re-reviewed the Turbak et al. 1986 study and agrees with Syngenta 

that this study should not be used for quantitative assessment of simazine risk to aquatic nonvascular plants. The study will be used qualitatively in risk characterization. Therefore the next 

most sensitive endpoint for aquatic non-vascular plants is currently from the Anabaena flosaquae taxon (36 ug a.i./L). The argument provided by Syngenta regarding the transformation of 

this value to a growth rate is noted and EFED will consider the transformation for this endpoint. 

As mentioned in the problem formulation, an open literature review will occur prior to the 

preliminary risk assessment and at that time the EFED will identify the final endpoints for use in 

the quantitative assessment. 

Syngenta Comment: Guideline numbers for Seedling Emergence 

(850.4225) and Vegetative Vigor (850.4250) have been revised in 40 CFR Part 158. 

EPA Response – EPA will use the updated guideline numbers in the risk assessment. 

Syngenta Comment: Syngenta has submitted a document to the registration review docket 

summarizing the types of refinements that should be considered for an endangered species 

assessment (Risk Assessment Considerations Concerning the Potential/Impacts of Pesticides on 

Endangered Species, Syngenta Report Number TK0181948).

EPA Response - EPA has reviewed the comments from Syngenta on the registration review 

docket openings for simazine and plans to address many of the concerns raised by Syngenta 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. EPA will 

address concerns specific to simazine in connection with the development of its registration 

review decision for simazine. 

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 
5

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. 

Response to Syngenta’s Comments on the Simazine Problem Formulation – 

Questions Related to Fate and Transport 

1 Page 6, 2.0 Environmental Fate Summary,

paragraph 2

“...hydrolysis at pH 4, 7 and 9

Syngenta Comment: Syngenta submits that the hydrolysis study was conducted at pH 5, 7 and 9.

EPA Response:  The EPA agrees with Syngenta that the hydrolysis study MRID 00027856 was

conducted at pH 5, 7 and 9.  EPA will correct this in the risk assessment.

2 Page 6, 2.0 Environmental Fate Summary,

paragraph 2  

”..with an aqueous solubility of 3.5 mg/L at

20°C....”  

Syngenta Comment: Syngenta respectfully requests to revise the aqueous solubility to 5.0 mg/L at

20°C.

EPA Response: All previous EPA documents concerning simazine, including the Simazine

Reregistration Eligibility Decision from 2006, as well as endangered species assessments, cite 3.5

mg/L at 20°C as the aqueous solubility, based on product chemistry data (MRID 00023955).  The

EPA will consider this revision if the study is submitted for evaluation, and would support  the use

of 5.0 mg/L at 20°C.

3 Page 6, 2.0 Environmental Fate Summary,

paragraph 3  

”..t 1⁄2 ranges from 89 to 859 days....”

Syngenta Comment: Syngenta respectfully requests to revise the half‐life range to read 89 to 137

days.

EPA Response: This half‐life range was included in the Problem Formulation in error.  The EPA

agrees that to be consistent with the aerobic soil metabolism half‐lives listed in Table 1 of the

Problem Formulation, the sentence should read, “Simazine is persistent in aerobic loam soils (t1/2

ranges from 80 to 137 days) and aerobic aquatic environments (t1/2= 97 days; MRID 43004501;

46561301; 43004502).”  EPA will correct this in the risk assessment.

4 Page 6, Section 2.Environmental Fate Summary, The half‐life of simazine for terrestrial field
6

5th paragraph; lines 2‐3 and Page 8, Table 1   study, MRID 40634202, is stated as 36 days in

0‐8” of soil.  

Syngenta Comment: It is unclear how this half‐life value was determined. Syngenta respectfully

requests that EPA provide clarification on the derivation of this value.

EPA Response: In calculating this half‐life, the EPA used Guidance for Evaluating and Calculating

Degradation Kinetics in Environmental Media, Health Canada, U.S. Environmental Protection

Agency, December 21, 2011 and subsequent guidance provided in EFED’s Standard Operating

Procedure for Using NAFTA Guidance to Calculate Representative Half‐life Values and

Characterizing Pesticide Degradation, November 30, 2012.  Based on this guidance, the tR IORE

model provided the best representative half‐life for the simazine data presented in this study.  

Note that data collected on days 269 and 553 were not included in the half‐life calculation, per

the guidance, because the measurements were below the limit of detection and/or quantitation.  

Half‐life calculation results from the program “R” are displayed below.

5 Page 6, Section 2. Environmental Fate Summary,

5th paragraph; line 4  

“....12 to 24 inches of soil....”  

Syngenta Comment: Syngenta believes this should read “18 to 24 inches of soil” as per Table 1 on

page 8 (MRID 00027863).

EPA Response:  The EPA agrees with Syngenta that this should read “....18 to 24 inches of soil....”

and will correct this in the risk assessment.

6 Page 8, Table 1: Environmental Fate Parameters

for Simazine (Value)  

The aquatic field dissipation half‐lives for

MRID 40614422 are 10 days and 80 days in

man‐made pond water and sediment,

respectively, in Iowa.  
7

Syngenta Comment: There is a discrepancy between the half‐lives shown and the source from

which these values were determined. It appears that the half‐lives were derived from an aquatic

field dissipation study conducted in Iowa (MRID 40614421), whereas MRID 40614422 is an aquatic

field dissipation study conducted in Georgia. Syngenta agrees that MRID 40614422 is the correct

source, and therefore, the half‐lives in Table 1 should be corrected to reflect the water and

sediment half‐lives determined from data reported from this study. It is unclear how the half‐life

values were determined, and Syngenta requests that EPA provide clarification on the derivation of

the half‐lives.

EPA Response:  Throughout the simazine problem formulation, the EPA cited MRID 40614422 (a

study conducted in Georgia) when describing data from MRID 40614421 (a study conducted in

Iowa).  Additionally, the EPA did not include the data from MRID 40614422 (a study conducted in

Georgia) in the problem formulation.  Data from both studies should be included in the problem

formulation.  This response and later responses to Syngenta’s comments on the simazine problem

formulation should address this issue.  Note that the EPA’s Data Evaluation Record (DER), which

included both studies, did not associate the correct MRID to its respective study, and erroneously

invalidated the field dissipation study conducted in Georgia (MRID 40614422).  Additionally, all

half‐lives calculated in the DER and by the registrant used average concentration data as opposed

to replicate data.  The EPA intends to make corrections to the DER (including associating the

correct MRID with each study and updating half‐lives using replicate data) and update it such that

both MRID 40614421 and MRID 40614422 will be classified as supplemental studies.

The simazine problem formulation published on June 26, 2013 contained aquatic dissipation half‐

lives for MRID 40614421 that were calculated using average concentrations from three replicates.  

The EPA has recalculated the aquatic dissipation half‐lives from this study and from MRID

40614422.  Below are the aquatic field dissipation half‐life calculation results for each study from

the program “R”.  Data from day ‐1/1 were not included in the half‐life calculation because the

data were collected prior to the first application of simazine.  Residue data from days 0/1 and ‐1/2

were not included in the half‐life calculation because the simazine was applied on two different

days with a non‐application day in between.  Data labeled as “NA” (or “not available”) were not

included in the half‐life calculation.  Finally, measurements of simazine that fell below the limit of

detection and/or quantitation were not included in the half‐life calculation, per the Degradation

Kinetics guidance.

In calculating the aquatic field dissipation half‐lives for MRIDs 40614421 and 40614422, the EPA

used Guidance for Evaluating and Calculating Degradation Kinetics in Environmental Media,

Health Canada, U.S. Environmental Protection Agency, December 21, 2011 and subsequent

guidance provided in EFED’s Standard Operating Procedure for Using NAFTA Guidance to Calculate

Representative Half‐life Values and Characterizing Pesticide Degradation, November 30, 2012.  

Based on this guidance, the Single First‐Order model provided the best representative half‐life for

the simazine data presented in both studies.  For MRID 40614421, the Iowa study, the aquatic

field dissipation half‐life estimates in water and sediment were 10 and 146 days, respectively.  For

MRID 40614422, the Georgia study, the aquatic field dissipation half‐life estimates in water and

sediment were 120 days and 1,551 days, respectively.
8
9
10

7 Page 6, Section 2. Environmental Fate Summary,

5th paragraph; lines 5‐6 and Page 8, Table 1:

Environmental Fate Parameters for Simazine

(Value)  

The half‐life in three aquatic field dissipation

studies is stated to “range from 10 to 700

days” (MRIDs 00027829, 40614420,

40614422)  

Syngenta Comment: The half‐life information for MRID 40614420 is missing in Table 1. Syngenta

suggests the half‐life value from this study be included. The aquatic field dissipation half‐life range

of “10 to 700 days” (page 6) may need to be corrected to reflect the updated aquatic dissipation

half‐lives reported in Table 1.

EPA Response:  The EPA respectfully disagrees with Syngenta.  The EPA does not believe it is

appropriate to include data from MRID 40614420, as data from this study are not expected to be

used quantitatively or qualitatively in the simazine ecological risk assessment for registration

review.   This is because the study investigates the extent and rate of dissipation in swimming

pools.  Swimming pool uses are no longer included on the simazine label.  Additionally, swimming

pool conditions are not representative of conditions that would be found in the general

environment, and would therefore not be appropriate for use in the ecological risk assessment for

simazine.  

8 Page 11, Table 2, Aerobic Soil Metabolism,

Degradation Products,  

MRID 43004501  

”...Hydroxysimazine (HS), 62.08%”  

Syngenta Comment: Syngenta requests to revise the percent of degradate, hydroxysimazine to

35.97%.

EPA Response:  The EPA respectfully disagrees with Syngenta, and does not intend to revise the

percent of degradate hydroxysimazine (identified in MRID 43004501 as substance G‐30414) to

35.97% in the problem formulation, as the study itself states the following on page 28:  

Since the retention time of G‐30414 was either at 3 or 23 minutes, depending on the extract,

quantification of this metabolite based on its concentration in Peak 4 (35.97% of applied

radioactivity by day 371) represents an underestimation. The percent of applied radioactivity

appearing as G‐30414 in the day 371 acetonitrile:water extract was determined by multiplying the

percent distribution on the TLC analysis of the extract (78.7%), by the percent applied radioactivity

in the extract as determined by LSC (average 33.18%; Appendix D). This resulted in a G‐30414

concentration of 26.11% of applied radioactivity in the acetonitrile:water extract. When the

percentage of G‐30414 detected in the acidified methanol, basic methanol and sodium chloride

extracts (8.37, 20.14 and 7.46% of applied radioactivity, respectively; Appendix D) were added to

the value obtained from the acetonitrile:water extract, it is estimated that G‐30414 represents

62.08% (6.83 ppm) of the applied radioactivity by the end of the study.

9 Page 12, Table 2. Identification of Simazine

Degradation Products in Environmental Fate

Studies (Maximum Percentage of Applied

Simazine (day)  

For the aquatic field dissipation study, MRID

00027829, the interval (days) associated with

maximum percentage of applied simazine for

DIA are:  

Florida: 90 d  

Washington: 27, 60, 90, 120, 150 d  

Oklahoma: 120, 400 d  

Arizona: 150, 200 d  

New York: 21, 60, 90 d

Syngenta Comment: Syngenta respectfully believes that the correct interval (days) per Table I of
11

the report are: Florida: 84 d, Washington: 27, 55, 90, 118, 146 d, Oklahoma: 121, 402 d  

Arizona: 150, 195 d, New York: 20, 55, and 91 d.

EPA Response: The EPA agrees with Syngenta’s revisions to the days associated with maximum

percentage of applied simazine for DIA in the aquatic field dissipation study MRID 00027829.  This

will be corrected in the risk assessment.

10 Page 12, Table 2. Identification of Simazine

Degradation Products in Environmental Fate

Studies (Maximum Percentage of Applied

Simazine (day)  

For the aquatic field dissipation study, MRID

40614422, the maximum percentage of DIA

and HS is 2.6 (1d) and 2.8 (1 d), respectively.  

Syngenta Comment: It appears that the maximum percentage information was determined from

another aquatic field dissipation study (MRID 40614421) not MRID 40614422. Syngenta agrees

that MRID 40614422 is the correct reference and the maximum percent of applied simazine for

DIA and HS should be 5.6 (1d) and 14.4 (0 d), respectively, based on an initial application of 2.5

mg/L.

EPA Response:  The EPA respectfully disagrees with Syngenta’s calculation of the maximum

percent of applied simazine for DIA and HS for MRID 40614422.  Although the problem

formulation’s reporting of the maximum percent of applied simazine for MRID 40614422 is

incorrect, Syngenta’s calculation is based on maximum average concentrations across replicates.  

Additionally, Syngenta’s calculation does not take into account that two applications of simazine

were made in the study, each of 2.5 mg/L, for a total application of 5.0 mg/L to the pond.

Because the replicate data are available in each study, the maximum percent of applied simazine

for MRID 40614421 and MRID 40614422 should actually be reported as follows, and are based on

two applications of 2.5 mg/L simazine (for a total application of 5.0 mg/L):

MRID 40614421 Iowa Pond Water:  

Maximum percent of applied simazine for DIA is 6.4% on day ‐1/2

Maximum percent of applied simazine for HS is 5.8% on days 0/2, 242. and 365

MRID 40614421 Iowa Sediment:  

Maximum percent of applied simazine for DIA is 2.4% on day 0/2  

Maximum percent of applied simazine for HS is 5.2% on days 242 and 365

MRID 40614422 Georgia Pond Water:  

Maximum percent of applied simazine for DIA is 14.8% on day 120

Maximum percent of applied simazine for HS is 28% on day 7

MRID 40614422 Georgia Sediment:  

Maximum percent of applied simazine for DIA is 5.6% on day 120

Maximum percent of applied simazine for HS is 1.4% on day 14

11 Page 12, Table 2. Identification of Simazine

Degradation Products in Environmental Fate

Studies (footnote*)  

“Maximum degradate concentrations in water

during the study period were 1.02 ppm on

day 9.....”  

Syngenta Comment: Syngenta believes the correct statement should be, ““Maximum degradate

concentrations during the study period were 0.68 ppm on day 120 for DIA and 1.27 ppm on day 7

for HS. Maximum degradate concentrations in sediment during the study period were 0.2 ppm on
12

day 120 for DIA and no residues (<0.05 ppm) were detected for HS.” (MRID 40614422, Tables 1

and 2).

EPA Response: The footnote identified by Syngenta does not appear to be associated with the

study mentioned in Syngenta’s comment.

The maximum degradate concentration in water of 1.02 ppm on day 9 is associated with MRID

40614420.  During the course of reviewing Syngenta’s comments, the EPA has determined that

MRID 40614420 should not have been included in the simazine problem formulation, as this study

investigates the extent and rate of dissipation in swimming pools.  Swimming pool uses are no

longer included on the simazine label.  Additionally, swimming pool conditions are not

representative of conditions that would be found in the general environment, and would

therefore not be appropriate for use in the ecological risk assessment for simazine.  

The EPA believes that the problem formulation (and Table 2 specifically) should, however, include

degradate data from both MRID 40614421 and MRID 40614422.  The maximum concentrations

currently reported in the problem formulation for MRID 40614421, as well as by Syngenta in their

comment, are maximum average concentrations across replicates.  Because the replicate data are

available in each study, the maximum concentrations of DIA and HS should actually be reported as

follows:

MRID 40614421 Iowa Pond Water:  

Maximum concentration of DIA is 0.16 mg/L on day ‐1/2

Maximum concentration of HS is 0.29 mg/L on days 0/2, 242, and 365.

MRID 40614421 Iowa Sediment:  

Maximum concentration of DIA is 0.12 mg/L on day 0/2

Maximum concentration of HS is 0.26 mg/L on days 242 and 365

MRID 40614422 Georgia Pond Water:  

Maximum concentration of DIA is 0.74 mg/L on day 120

Maximum concentration of HS is 1.40 mg/L on day 7

MRID 40614422 Georgia Sediment:  

Maximum concentration of DIA is 0.28 mg/L on day 120

Maximum concentration of HS is 0.07 mg/L on day 14

12 Page 34, Appendix A, Table A‐1., CAS Number,

Name, Chemical Formula

“CAS number not found.”

Syngenta Comment: Syngenta respectfully submits the CAS number as 673‐04‐01.

EPA Response:  The EPA respectfully acknowledges the CAS number as 673‐04‐01.