1 

### EFED response to public comments from Syngenta

3.0 ECOLOGICAL RISK

Comment 1: 3.1 Ecological Risk Assessment Endpoints: As the Agency intends to utilize endpoints from surrogate test species to es timate treatment-related effects on acute mortality and chronic reproduc tive, growth and survival assessment endpoints, it is important to ensure the mo st appropriate values for a particular taxon are used.

EFED Response: For baseline ecological risk assessments, EFED uses the most sensitive data available ( e.g. , lowest LC 50 ) that comply with Harmonized Test Guidelines

and Good Laboratory Practices Standards . Other toxicity endpoints may be used if professional judgment and lines of evidence determine that they can be linked to assessment endpoints in a reasonable manner. 1 Fish are used as surrogates for aquaticphase amphibians, for which toxicity data ar e not typically available for pesticides. In addition, birds are used as surrogates for terrestrial-phase amphibians and reptiles.

Comment 2: 3.1.1 Avian Reproduction NOAEC with TGAI: On page 8, Table 2, the NOAEC of 350 mg prodiamine/kg diet (ppm) listed for the bobwhite quail reproduction study endpoint does not correspond to the va lue of 1000 mg/kg diet (ppm) prodiamine generated in the cited study (Beavers et al. , 1992, MRID 43181803). Syngenta requests that this endpoint be updated to 1000 mg/kg in future reviews.

EFED Response: MRID 43181803 was originally classified as invalid because performance of control birds was poor compar ed to historical control data for the bobwhite quail indicatin g that potential reproductive e ffects may have been masked. Equipment malfunction was cited as the cause for loss of eggs and hatchlings which increased test variability. 2 Later, the study was reclassified as acceptable 3 only by adjusting the NOAEC to 350 ppm, the second hi ghest test concentration, rather than 1000. After examining the data, which s howed probable effects at 1000 ppm, a determination was made that any statistica lly significant difference from controls was masked by the high variability of the data. Th erefore, the registrant was given the option of repeating the study if they be lieved this value to be ina ppropriate. Since the study was not repeated, the NOAEC remains at 350 ppm and the LOAEC at 1000 ppm.

1 http://www.epa.gov/oppefed1/ecori sk_ders/toera_analysis_eco.htm

2 Data Evaluation Record, May 24, 1994, fo r “Beavers, J.B., K. Chafey, L. Mitc hell and M. Jaber. 1992. Prodiamine Technical: A Reproduction Study with the Northern Bobwhite. Prepared by Wildlife International Ltd., Easton, Maryland. Laboratory Project No. 131-170. Submitted by Sandoz Agro, Inc., Des Plaines, IL. EPA MRID No.

431818-03.

3 Doug Urban for Anthony Macriowski, EFED to RD, November 15, 1994. EPA Internal Memo. Prodiamine: reclassification of avian repro duction study with bobwhite quail.2 Comment 3: 3.1.2 Freshwater Fish Early Life Stage Study with TGAI: On page 9, Table 3a, Freshwater fish ELS is identifie d as a data gap. A st udy report has been submitted previously (Graves and Swiger t, 1993; MRID 42807103) and rated as CORE. Syngenta requests that this study be c onsidered in future reviews.

EFED Response: EFED has re-reviewed this study and reclassified it as supplemental due to uncertainty associated with the test concentrations. Prodiamine concentrations in

the test were at or near sol ubility, and water samples were not centrifuged or alternatively filtered prior to processing and analysis. Centrifugation or filtration is important for prodiamine because the high Log Kow suggests that it may bind to organic carbon in the test system, which may limit its bioavailability and affect its toxicity.

Comment 4: 3.1.3 Freshwater Invertebrate ( Daphnia magna ) Life Cycle Study with

TGAI: On page 9, Table 3a, the cited chronic daphnia study (MRID 41787302) was considered supplemental and a daphnid repr oduction study was identi fied as a possible data gap. However, a more recent study by Zelinka et al., (1993, MRID 42807102) was submitted previously and rated as CORE. The NOEC for this CORE study was 23 ppb, while that for the cited unacceptable study re sulting in the data gap statement (MRID 41787302) was reported as 1.5 ppb. Syngenta reque sts that this Zelinka study (MRID 42807102) be used for the chronic fres hwater invertebrate endpoint.

EFED Response: The previously submitted daphnid life cycle study (MRID 42807102) was downgraded to Invalid due to a re-analy sis of the data that showed unacceptable differences between the negative and solvent c ontrols and uncertainty associated with the actual test concentrations, which were at or near the solubility lim it but not centrifuged or alternatively filtered prior to processing and analysis.

Comment 5: 3.1.4 Freshwater and Saltwater Fish Full Life Cycle (FFLC) Studies with

TGAI: On page 9, Table 3a, EPA identifies FFLC studies with freshwater and estuarine/marine species and TGAI as possi ble data gaps (850.1500). FFLC data can be required if the product is intended for direct application to water, or if the product is expected to enter water in significant concen trations. There is a use of prodiamine for irrigation ditch banks; however Syngenta produ cts are not labeled for this type of application, and Syngenta does not support the use. The envi ronmental fate profile of prodiamine indicates that this AI is unlikel y to enter water via run-off in significant concentrations, thus aquatic exposur e is expected to be low.

Further, based on the very short aquatic half -life of prodiamine and the availability of chronic data on fathead minnows; Syngenta sugg ests that the conduct of freshwater or saltwater FFLC studies does not provide a dditional useful input for risk assessment

.

EFED Response: EFED’s request for the freshwater and saltwater fish full life cycle data was based on more than the irrigation ditc h use. All outdoor uses have the potential3 to enter freshwater, and several of the uses ( e.g. , turf) would also be expected to be used

in areas with access to sa ltwater environments.

Per footnote 18 to Guideline 850.1500 (40 CF R Part 158.630, Subpart G), a freshwater fish full life-cycle test is required when a pr oduct is “expected to be transported to water from the intended use site, and when a ny of the following conditions apply:

i. If the ...(EEC) is ≥ 0.1 of the no-observed-effect level in the fish early-life stage or invertebrate life cycle test;

ii. If studies of other organism s indicate that the reproductive physiology of fish may be

affected.”

EFED believes that the conditions for requiring a freshwater fish fu ll life cycle test (as defined in footnote 18) are met for prodiamin e. As indicated on pp. 39-40 of the problem formulation, available data for prodiamine indicate that “potentia l reproductive effects on fish (egg production and hatchability) and endpoints in birds were reduced (MRID 43181803) and reduced offspring weights in rats (MRID 40593421) and the EEC according to the GENEEC screen is > 0.1 of the NOAEC value (using the NOAEC value from a supplemental freshwater inverteb rate study, (MRID 41787302)). Additionally, prodiamine has potential to bioaccumulate whic h may result in reproductive effects that an Early Life Stage test would not capture.”

Similarly, footnote 17 to the gui deline indicates that an estuarine/marine fish life cycle study is required if “the produc t is expected to enter this environment in significant concentrations because of its expected use or mobility patterns.” Some registered uses for prodiamine are geographically widespr ead and certainly allow exposure to the saltwater environment ( e.g. , turf).



### 3.2 Projection of Prodiamine and Prod iamine Benzimidazole Toxicities to Aquatic Organisms using Quantitative Structure-Activity Relationships:

Comment 6: 3.2.1 Estimation of Toxicity Endpoi nts for Prodiamine Parent TGAI: On page 10, Table 3b, QSAR modeling is used to estimate toxicity endpoints for TGAI. However, study-derived endpoints are available for many of these toxicity values. It is notable that the values estimated by QSAR in Table 3b overestimate the available measured toxicity values. Most of the QSAR values are well above th e water solubility of prodiamine. Syngenta requests that measured va lues be used when available, and that estimations of toxicity be made using c onventional methods that involve measured toxicity inputs for the AI in question, e.g. for the calculation of acu te-to-chronic ratios.

EFED Response: QSAR estimates for pesticides a nd degradates are used in conjunction with empirical toxicity data on a case-by-case basis for estimates, such as comparisons4 between parent and degradate when data are not available. The purpose of Table 3b on p. 10 was to illustrate how toxicity of prodiamine parent would be expected to compare with that of degradate, prodiamine benzim idazole. EFED included the QSAR estimates in order to predict whether prodiamine would be expected to be more or less toxic than prodiamine benzimidazole.

Comment 7: 3.2.2 Estimation of Toxicity Endpoi nts for Prodiamine Benzimidazole Degradate: On page 10, Table 3b, acute and chroni c aquatic toxicity values derived using QSARs are presented for the degradate, prodiamine benzimidazole. EPA states that model estimates indicate the degradate may have similar acute toxicity to the parent, and greater chronic toxicity compared to pa rent prodiamine. Based on these modeled estimates, numerous acute and chronic aquatic toxicity studies have been identified as potential data gaps. Results from laboratory studies demonstrate th at the environmental fate profile of prodiamine benzimidazole does not present a risk for chronic exposure due to its short aquatic half-life, as described below.

Syngenta suggests that the conduct of ex tensive aquatic studies on prodiamine

benzimidazole would not be useful due to th e brief and very limited potential exposure of aquatic organisms to this degradate.

EFED Response: This degradate is a major degrad ate with a structure similar to the parent and appears to be stable under some conditions. EFED considers this degradate to be of concern for chronic exposure. The problem formulation states on p. 13, “The only major metabolite was 6-amino-2-ethyl-7-nitro -1-propyl-5-trifluoromethyl-benzimidazole (prodiamine benzimidazole). The benzamidazole concentration peaked at 0.82 μg/g (33% of applied) at 270 days, and had declined to 0.74 μg/g (29.60% of applied) at 365 days” (MRID 4059342). While photolysis (as mentioned below) may degrade the benzimidazole degradate, photolysis would be unlikely to be fast enough to eliminate acute risk or be thorough e nough to eliminate chronic risk.



### 3.3 Environmental Exposure

Comment 8: 3.3.1 Henry’s Law Constant: On page 12, Table 5, the value given for the Henry’s Law Constant is 8.89x10-2 atm-m3/mol . The correct value is 8.89 x 10-7 atmm3/mol (Erstfeld, 1987).

EFED Response: The Henry’s Law Constant va lue in Table 5 (i.e., 8.89 x 10 -2

atm·m 3 ·mol -1 ) appears to be typographical error. EFED agrees that the Henry’s Law Constant for prodiamine should be 8.89 x 10 -7 atm·m 3 ·mol -1 . This value is calculated from the vapor pressure and solubility valu es listed in the Regist ration Review Problem

Formulation.5 This value may also in fact not be correct as the cited vapor pre ssure value cannot be tracked to a measurement. The citation pr ovided (Erstfeld, 1987) is not complete. A search of the public literature and through doc uments submitted to the Agency to support prodiamine registration for those Erstfeld fr om 1987, both regarding prodiamine Henry’s Law Constant specifically or chemical physi cal properties in genera l, did not find this

citation. Other available citati ons for the Henry’s Law Consta nt and vapor pressure all further cite the British Crop Protection Manua l. This is not a primary source based on measurements and cannot be used to support pe sticide risk assessments for FIFRA. In the

absence of citable measured for values fo r vapor pressure and/or the Henry’s Law Constant, the Agency will assess the risks of prodiamine using QSAR estimates from tool

such as EPISuite. The current best estimat e of vapor pressure for prodiamine from

EPISuite is 2 x 10 -7 torr and for the Henry’s Law Constant is 5 x 10 -8 atm·m 3 ·mol -1

.

Comment 9: 3.3.2 Fate and Transport Properties: On page 13, Table 6, the cited mobility parameters for prodiamine reflect Kd values calculated using a linear isotherm model. However, based on the current te st guidelines (OECD 106 and OPPTS 835. 1230)

the Freundlich isotherm mode l is preferred. The Freundlich isotherm results were given in the cited report (MRID # 40593525) within Appendix 1 (pp. 317-336). The Koc values calculated using the Freund lich adsorption isotherm ra nged from 8035 to 16283 mL/g with a mean Koc of 11,195 mL/g. Syngenta requ ests that the Freundlich isotherm-derived values be used, as per OECD and EPA guidance.

EFED Response: The study cited in the Registrati on Review Problem Formulation for prodiamine is a column leaching study. The cited MRID of 40593525 is not correct. The correct MRID is 40593425. Estimates of parti tion coefficients from column leaching

studies are much less accurate than those for batch equilibrium studies. An acceptable batch equilibrium study is available for prodiamine (MRID 41727202). While visual inspection of the data indicates the the isot herms are curvilinear, the study authors only

estimate K d for adsorption and desorption for th e soils in the study. The measured K d for adsorptions were 119.7 and 303.9 L·kg for a’#58’ clay and a Kenyon silt loam respectively. Given that these data are likely to be much more accurate, these values will

be used in the risk assessment rather than those from the column leaching study. Fruendlich coefficients will be calculated from the original data for use in the risk

assessment.

Comment 10: On page 13, Table 6, the prodiamine aerob ic soil half-life is given as 57 days. Using the data points in the cited report (MRID # 4059342), half-lives were re-calculated by two different non-linear kinetic methods to determine the best fit: single first order (SFO) and double first order in parallel (DFOP). Based on the linear regression coefficients (R2), the DFOP gave an excellent fit (R2 of 0.9996) with a calculated aerobic soil half-life of 42.1 days. The SFO approach provided a half-life of 56.6 days (R2 of 0.9734). Syngenta suggests that th e appropriate aerobic soil ha lf-life value is 42.1 days.6 EFED Response: The value reported in the Table 6 is a correctly estimated first-order half-life estimated using non-lin ear regression on untransformed concentration data. Note

that because all EFED environmental fate m odels use first-order ki netics, estimates of

first-order rate constants mu st be estimate for use in simulation modeling. Alternative

kinetics models such as DFOP is not first order and the kinetics parameters from DFOP

cannot be used in the models.

Comment 11: On page 13 and in Appendix I – The physical-chemical properties as well as the environmental fate and ecological effects of prodiamine are well characterized in accepted EPA guideline studies. (See endpoint s presented in Tables 2, 3 and 5). Estimation of prodiamine’s persistence using the Level III fugacity model in EPI-SUITE v4.0 is not appropriate for chemicals with we ll characterized fate and effects data. The use of the screening level model, PBT Profiler, to assess the persistence, bioaccumulation, and toxicity of prodi amine and its degradate (prodiamine benzimidazole) is not appropriate since the model is clearly not intended to be used for chemicals with experimental data.

EPA Response: The Agency agrees that measured environmental fate data should be used preferentially to estimates based on the structure-activity relati onships in pesticide risk assessments. However, the estimates ma de using the EPI-SUITE’s Level III fugacity provide useful ancillary information for charact erizing the behavior of prodiamine in the

environment.



### 3.4 Risk Hypothesis

Comment 12: 3.4.1 Analysis Plan: In Section13.A.2, on page 20 of the EFED problem

formulation document the maximum use rate of 2.64 lbs ai/A cannot be confirmed. Based on Appendix V of the same document, “Uses and Application Rates of Prodiamine”, the maximum annual rate is 1.5 lb ai/A/yr. Base d on this rate, Syngenta calculates a 90th percentile EPA-defined pond drift EEC as 5.18 ppb using AgDrift 2.01.

EFED Response: For the Registration Review ecological risk assessment, EFED will

base maximum use rates on all current labe l information. EFED will reconsider the

maximum annual use rate at that time.



### 3.5.1 Environmental Fate (pg 28-29)

Comment 13: 3.5.1.1 Proposed data gap: 835-2240, Photodegradation in Water (Parent Prodiamine): Syngenta has recently submitted a study entitled Photolysis of

14C-Labelled Prodiamine in Sterile Natu ral Water and Sterile pH 7 Buffer under Laboratory Conditions , by A. D. Hurt, G. Mason and K. Anderson, 15 September 20057 (MRID 48308301). This study was conducted to comply with Japanese and OECD guidelines and should also address EPA que stions regarding the photodegradation of parent and prodiamine benzimidazole (SYN-530120). The study demonstrated that prodiamine rapidly degrades photolytically with half-lives of less than 8 hours in both sterile natural water and pH 7 buffer.

EFED Response: The cited study is curre ntly being reviewed by EFED. If the study is scientifically valid, the data wi ll be considered in the regist ration review risk assessment.

Comment 14: 3.5.1.2 Proposed data gap: 835-2410, Photodegradation in Soil (Parent Prodiamine): Syngenta has recently submitted a study entitled Artificial Sunlight Photodegradation of 14C-Prodiamine on a Representative Agricultural Soil by R. N. Fathulla, 17 January 1996 (MRID 48308302). Prodiamine photodegraded rapidly in treated soil (half-life of ~5 days). Pr odiamine benzimidazole was only a minor photodegradate (peak at 1.9% applied radioactivity) and underwent further photodegradation.

EFED Response: The cited study is curre ntly being reviewed by EFED. If the study is scientifically valid, the data wi ll be considered in the regist ration review risk assessment.

Comment 15: 3.5.1.3 Proposed data gaps: 835-4300, aerobic aquatic metabolism (Parent Prodiamine) and 835-4400, ana erobic aquatic metabolism (Parent Prodiamine): Syngenta is submitting a study entitled Prodiamine – Degradation of [14C]-Prodiamine in Two Aquatic Sedime nt Systems, under Aerobic and Anaerobic

Conditions , by M. Simmonds and E. Macken zie, 3 September 2009 (Syngenta Report/Study Number NC/08/043) . Aerobic and anaerobic aqua tic sediment studies were conducted separately to satisfy OECD guide lines (308), but reporte d in a single final report. Key findings demonstrated:

• Aerobic Aquatic Sediment:

• Prodiamine dissipation half-lives in both system water phases were very rapid (1-5 days).

• Parent total system half-lives in bot h test systems ranged from 14.4-17.5 days.

• Only trace amounts of prodiamine benzim idazole were found in the water and sediment phases of both test systems.

• Anaerobic Aquatic Sediment:

• Prodiamine dissipation half-lives in both system water phases were rapid (2-5 days).

• Parent total system half-lives in both te st systems were even more rapid (3-7 days) than under aerobic conditions.

• Prodiamine benzimidazole was only found in trace levels in the sediment phase of both test systems.8 An anaerobic soil metabolism study entitled Anaerobic Soil Metabolism of Prodiamine by J. Krueger and R. Butz, January 21, 1988 (Sandoz Crop Protection Project # 480425, report # 4) is being submitted. This study substantiates the findings in the anaerobic aquatic metabolism study (see above) and also provides insight into the environmental fate of prodiamine benzimidazole. In the repo rt an aerobic-anaerobi c half-life (0-93 day after treatment, DAT) of 30 days was calcu lated. However, under induced anaerobic conditions (30-93 DAT), the anaerobic soil half-life of prodiamine was considerably shorter, only 11.7 days. Prodiamine benzimidazole (SYN530120) reached a peak level of 8% applied radioactivity (AR) at 30 DAT. Thereafter, under induced anaerobicity (30-93 DAT), SYN530120 readily declined with an estimated half-life of 25.6 days (SFO).

EFED Response: EFED will review these studies when they are submitted. If the studies are scientifically valid, the data will be considered in the registration review risk

assessment.

Comment 16: 3.5.1.4 Proposed data gap: 835-6200 Aquatic Field Dissipation (Parent Prodiamine): None of Syngenta’s product labels a llow for direct aquatic application nor does Syngenta support aquatic uses. In th e event prodiamine should move off-target due to turf runoff or spray drift it would di ssipate quickly due to degradation by sunlight and aerobic metabolism processes.

EFED Response: The aquatic field dissipation study is ony required to support aquatic uses. Application to irrigation d itches is considered an aquatic use. Therefore, in order to fulfill this data gap, registrants who s upport this use should provide the data.

Comment 17: 3.5.1.5 Proposed data gap: 835-2240, Photodegradation in Water (prodiamine benzimidazole, SYN530120): As indicated above, Syngenta has recently submitted photolysis studies which should addr ess questions regarding the behavior of prodiamine benzimidazole unde r photolytic conditions:

From these two photolysis studies, prodiam ine benzimidazole was found as only a minor or transitory photodegradate wh ich rapidly underwent further de gradation to one or more photodegradates.

Syngenta contends that the e-fate of bot h prodiamine and prodiamine benzimidazole (SYN530120) are well underst ood and supported by existing studies. Available e-fate data clearly indicate SYN530120 is not of c oncern environmentally since it is degraded rapidly under photolytic, aquatic/sediment ( aerobic and anaerobic) and anaerobic soil conditions. The photolysis and mobility studi es clearly indicate that under field conditions SYN530120 photodegrades rapidly and is likely only a minor metabolite with low leaching potential.9 EFED Response: As noted in the response to Co mment 12, the two photolysis studies are currently being review ed by EFED. Also, as noted in Comment 16, the aquatic/sediment studies are forthcoming, and have not yet been submitted or reviewed. Together, these data may be used to eval uate the potential ex posure potential of the degradate. If the studies are scientifically valid, the data will be considered in the registration review risk assessment.

Comment 18: 3.5.1.6 Proposed data gap: 835-1230, Adsorption/desorption (batch equilibrium) (using SYN530120 ak a 6-amino-benzimidazole): A legacy company of Syngenta, Sandoz Crop Protection, conducted an aged soil column leaching study per specific EPA guidance in addressing the mobility of SYN530120. The study was entitled Soil Column Leaching of 14C-Prodiamine and Its Soil Degradates , by Tsun-Min Rosa Tong, Rakesh Jain, Paul Moore, and Yousef Atallah, September 1992 (MRID # 42483201). On 10-23-91, Brinson Perks (an EPA reviewer) recommended Sandoz use the soil column leaching method instead of the earlier proposed batch equilibrium method

in order to address EPA’s concerns on th e mobility of SYN530120 (see Appendix 1 in cited report, in particular, the original pr otocol objectives and subsequent protocol amendment 1 following EPA guidance). Kd and Koc values are provided in Appendix V of the report (pages 104-107) which clearly demonstrate both pare nt and SYN530120 are not likely to leach.

EFED Response: While leaching studies are adequate for showing a pesticide does not leach, current risk assessment methods requi re a quantitative estimate of mobility ( i.e.

K d ) in order accurately account for mobility. Aged column leaching studies do not provide accurate estimates of K d for compounds of moderate and lower mobility and are no longer solely acceptable for meeting pe sticide mobility data requirement. An acceptable batch equilibrium study, MRID 41727202, discussed in Comment 10 above was submitted to the Agency and will be used to quantify mobility rather than the column leaching study.



### 3.5.3 Studies on Degradates

Comment 19: 3.5.3.1 Proposed data gap: Guideline Number 850.1400, Freshwater and Saltwater Fish Early Life Stage St udy with benzimidazole degradate: The chronic exposure to the degradate, prodiam ine benzimidazole, for aquatic organisms is expected to be very low. This degradate is a short-lived intermediate in the aqueous photolysis of prodiamine (see comment a ddressed in 3.5.1.5), and therefore will not represent an environmentally-re levant metabolite in the field, particularly for chronic

exposure.

EFED Response: Please see EFED Response 16.10 Comment 20: 3.5.3.2 Proposed data gap: Guideline Numbers 850.1300 and 850.1350,

Freshwater and Saltwater Invertebrate Life Cycle Toxicity Study with benzimidazole degradate: The chronic exposure to the degradate, prodiamine benzimidazole, for aquatic organisms is expect ed to be very low. This degradate is a short-lived intermediate in the aqueous photol ysis of prodiamine (see comment addressed in 3.5.1.5), and therefore will not represent an environmentally-relevant metabolite in the field, particularly for chronic exposure.

EFED Response: Please see EFED Response to Comment 16.

Comment 21: 3.6 Testing of Prodiamine TEP (Formulation): Results of ecotoxicity testing of prodiamine TEP have been identifi ed as potential data gaps, including daphnid acute, oyster embryo larvae or shell deposit ion, and mysid acute studies. 40 CFR 158 requires data for TEP for products applie d to water, OR when the maximum EEC ≥ 0.5 LC50, OR when the end product pr oduces increased toxicity:

• There is a use of prodiamine for irri gation ditch banks. However, Syngenta products are not labeled for this type of application a nd Syngenta does not support the use. There is thus no application to water.

• Preliminary modeling by Syngenta indi cates that the maximum EEC is not ≥ 0.5 LC50. Syngenta requests that EP A confirm the EEC/LC50 ratio for Syngenta-labeled uses in order to verify whether this trigger for TEP testing is

met.

• Finally, there is no indication that the end product produces increased toxicity; formulations are typically less toxic on an a.i. basis than te chnical ingredient ( e.g. Mayer and Ellers ieck, 1986; Schmuck et al . 1994).

In addition, with an EC50 value of 0.37 mg/L, mollusks are one of the least sensitive taxa to prodiamine. Syngenta suggest s that studies on the TEP should not be triggered for Syngenta-supported uses.

EFED Response: In answer to the first bullet (Syngenta products are not labeled for ditch bank uses), the data requirement is trig gered for the ditch bank use regardless of the identity of the registrant that supports this use. If no registrant supports the ditch bank use, then the data would not be required.

For the second bullet, concerning max EEC and TEP testing, the second condition mentioned above (from 40 CFR Part 158) is me t. Applications of approximately 1 lb a.i./acre by aerial spray result in drift only EECs that are approximately 1⁄2 the solubility limit of prodiamine in the standard pond. Th e maximum application rate of prodiamine is 2.64 lbs a.i./A. Therefore, determini ng whether or not ingredients found within11 formulated products of prodiamine may enhance its toxicity or solubili ty is useful to the

risk assessment.

For the third bullet, if the registrant believe s that the formulated products used in cited sources are representative of TEPs, then they can submit those data and the justification of the test formulations as TEPs to fulfill this data gap.

The registrant may submit for consideration a waiver request for the mollusk data further outlining their justification.