### 2 

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

–

Questions Related to Ecological Data

Syngenta Comment: The acute freshwater invertebra te 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 c oncentrations were not re ported nor analytically

confirmed, 3) raw data were not reported and a co ncentration-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 invertebra te 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 EC 50 

### = 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 MR ID 46561305 indicate no acute effects on aquatic

invertebrates at concentrations at or above the solubility of simazine.

EPA Response - EFED recognizes that there are deficienci es 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 consid ered as an important part of conducting a study,

EFED routinely accepts non-GLP Guideline studie s 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 end points in terms of a Tole rance Level, which the

authors explain was estimated using a modified Litchfield Wilcoxon sta tistical 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 Decisi on, the acute freshwater invertebrate study submitted by Syngenta

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

observed at all treatment levels >3.2 mg/L indica ting that the solvent (t etrahydrofuran [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 satu rator columns, sonication, centrifugation, etc.);

3) mean-measured concentrations provided by th e study author are not re presentative of the

bioavailable or dissolved fracti on 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 solven ts 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 aforem entioned inconsistency and data

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

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

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

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

Syngenta has identified a D. magna 21-d reproduction GLP-study pe rformed 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 Synge nta 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 probl em formulation used at razine data from MRIDs

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

140 μ g 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 μ g a.i./L (MRID 44332760),

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

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

endpoint will be made in light of the review of the Rufli (1989) report on ce 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 considerab ly detracts from the overall quality of the

study. The test material in Table 3 is also re ferred 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 substantia lly more scientifically robust. This study

was completed with sheepshead minnow and no mort alities or sublethal e ffects were observed at

the highest test concentrati on (4300 ug a.i. /L). The 96-h LC 50 

### 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 assessm ents. Furthermore, Syngenta

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

than E76270; as such, the ch ronic 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 th e E76270 study was the 90%

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

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

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

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

those reported in E76270, they will be consider ed 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 th at data from the GLP study MRID

42662401 is far more scientifically r obust 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. Th is 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 thos e based on standing crop

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

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

than abundance for establishing effect concen trations for aquatic plants. Based on the

aforementioned information and that relative grow th 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 reca lculation 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 quantitat ive assessment of simazine risk to aquatic nonvascular plants. The study will be used qualitative ly in risk characterization. Therefore the next

most sensitive endpoint for aqua tic non-vascular plants is cu rrently from the Anabaena flosaquae taxon (36 ug a.i./L). The argument provide d by Syngenta regarding the transformation of

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

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

preliminary risk assessment and at that time th e 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) ha ve been revised in 40 CFR Part 158.

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

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

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

assessment (Risk Assessment Considerations Con cerning 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 addre ss many of the concerns raised by Syngenta as

part of the implementation plan fo r 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 conne ction with the development of its registration

review decision for simazine.

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

recommendations on specific scientific and tech nical issues related to the development of

pesticide risk assessments that are compliant w ith the Endangered Species Act and the Federal

### 5 Insecticide, Fungicide, and Roden ticide Act. In November, the EP A, along with the U.S. Fish &

Wildlife Service (USFWS), the National Marine Fisheries Service (NMFS) (collectively, the

Services), and the U.S. Department of Agricultu re (USDA), released a summary of their joint

Interim Approaches for assessing risks to li sted species from pesticides. The Interim

Approaches were developed jointly by the Agen cies 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 Decembe r 2013 PPDC and SFIREG meetings, allowing

additional opportunities for stake holders 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 appro aches as part of a phased iterative process.

EPA will refine its listed species risk assessmen ts 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 Ac t 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 th e 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 (t 1/2

ranges from 80 to 137 days) and aerobic aquatic environments (t 1/2 = 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 D egradation, November 30, 2012. Based on this guidance, the t R 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 pro gram “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. Syng enta 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 clarifica tion 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 sho uld 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 Geo rgia (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 replica te 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 aqua tic 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. Resi due 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 li mit 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. Environment al 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 dissipati on 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 an d 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 Tabl e 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 swi mming

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 eith er 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 distri bution 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 meth anol, 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 ini tial 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, Syngen ta’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 a ctually 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 S ediment:

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

Maxim um 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 no t 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 envi ronment, 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 Syn genta 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

Maxim um 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

Maxim um 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.