2

EFED Response #1 :

EFED agrees that the use of modern nozzles that incorporate spray

- drift reduction technology and produce courser sprays would reduce spray drift, and would result in shorter distances from the fields where the spray drift exposure exceeds the EC 05

. However, a ll applicators are not using nozzles with

sp ray

- drift reduction technology. Some applicators are expected to use nozzles that produce very fine to fine droplets, which is the default setting for ground spray in the AgDrift model. All product labels would need to be modified to require the use of noz zles designed for reduced spray drift , or specify limits on the allowable coarseness of the ground spray, before it would be appropriate to change the

default droplet

- size parameter used in the AgDrift model to generate spray drift estimates for a quantita tive risk assessment

.

Likewise, EPA ’s policy is to base the analysis on the upper 90 th percentile spray drift deposition values. This differs from the analysis that DAS presents, which was based on the 50 th percentile. EPA’s policies on the use of input parameters for modeling pesticide spray drift are described in the EFED memorandum of December 20, 2013 entitled Guidance of Modeling Offsite Deposition of Pesticides via Spray Drift for Ecological and Drinking Water Assessments

.

In DAS ’s spray drift modeling for f lumetsulam, they make use of spray drift data collected by Agricultural and Agri

- Food Canada. While EFED has evaluated the spray drift deposition data

s ubmitted by Crop Life America (i.e., the “Canadian data” or “Wolf data”), i ssues with the completeness of data prevent EFED from using the information for quantitative purposes. EFED is in the process of evaluating all spray drift data that have been submitted to the Agency and developing a policy for the use of existing and futu re deposition data in the conduct of its assessments. Until this policy has been formalized, EFED will continue to use methods developed in its Guidance on Modeling Offsite Deposition of Pesticides Via Spray Drift for Ecological and Drinking Water Assessme nts document in the quantitative assessment of spray drift, while using supplemental data submitted to the Agency for characterization purposes. The only exception would be for spray drift deposition data, generated specifically for the active ingredient/f ormulated product being assessed. Such data could be used for quantitative purposes, if found to be acceptable by the Agency

.

DAS Comment #

2 : Frontrow Herbicide (62719

- 299) has been cancelled

Frontrow Herbicide (62719

- 299) should not be included in the list of registered products discussed in the use profile because Dow Agroscience has submitted a cancelation notice for this product.

EFED Response #

2 :

EFED defers to the Registration Division on the current registration sta tus of this product.3

DAS Comment #

3 : The use profile table was corrected to reflect current labels

DAS marked several corrections to the information provided in Table 2.5 (Summary Use Profile for

Flumetsulam ). While this table appears in the Human Health section of the PRA, DAS indicates that

some of the errors also occur in Table 3 of the section on ecological risk and need to be corrected

.

EFED Response #

3 :

Table 3 in the preliminary ecological risk assessment portion of the PRA differs from Table 2.5 of the

human health section . Table 2.5 gives the maximum application rates for every registered product

, whereas Table 3 only list s the maximum application, on any label, per crop and app lication timing

. Some of the information in Table 3 is based on labels of products of companies other than DAS

. Also,

Table 3 does not attempt to list the use restrictions and limitations in the details given in Table 2.5. After

review of the corrections t hat DAS made to Table 2.5, we did not find that any corrections were needed

for Table 3 of the preliminary ecological risk assessment.

DAS Comment #

4 : Recommends quantitative use of monitoring data

In reference to the discussion of monitoring data on pages 28

- 30, DAS claim that the monitoring data shows convincing evidence that the high end of flumetsulam concentrations in the aquatic environment is less than 1 μg/L. They disagree that these monitori ng data should only be considered as qualitative information in the ecological risk assessment.

EFED Response #

4 :

EFED does and will consider monitoring data, but without sufficient additional ancillary information, monitoring data by itself is often difficult to interpret. The frequency of sampling in monitoring programs is generally insufficient to determine the peak concentration. Additionally, m onitoring data frequently does not provide adequate information concerning the surrounding land use or pe sticide use

at or upstream , flow rates, or with a hydrologic connection to the monitoring site.

DAS Comment #

5 : Reported I C

50 for green algae is not correct.

DAS notes that the 5

- day IC 50 that the risk assessment reports for a green algae toxicity study (MRID 41931743) was 3.21 μg a.i./L, whereas the result reported in the study report was 4.93 μg a.i./L, and the same endpoint was previously reported in another EPA document as 3.31 μg a.i./L.

EFED Response #

5 :

T he I C 50 endpoint value reported in the risk assessment, 3.21 μg a.i./L, is the I C 50 endpoint that was reported in the DER. The endpoint value of 3.31 that was reported in a previous EPA document appears4

to be a typographical error. In reviewing the DER for this study , we became aware that the data were analyzed by EPA using probit analysis, a method that is not appropriate for analyzing cell count data. This explains why the 5

- day IC 50 reported in the original DER differed from that reported in the study

re port. EPA therefore reanalyzed the cell count data using the CETIS software and applying a weighted nonlinear regression method for analyzing continuous data ( Bruce and Versteeg

, 1992). The 5

- day IC 50 calculated by CETIS was 4.76 μg a.i./L, which is simi lar to the value reported in the study report (4.93 μg a.i./L).

EPA policy is to use the 4

- day (96

- hr) IC 50 to calculate RQ s for risk to nonvascular plants . CETIS was therefore used to analyze the 4

- day cell count data reported in this study. The 4

- day IC 50 was determined to be 3.52 μg a.i./L. Correcting the algal toxicity RQs using the correct 4

- day IC 50 value (3.52 μg a.i./L) would reduce the RQ values for nonvascular plants by only a factor of 1.1. This would have little effect on the RQ values and would not change any of the risk conclusions for nonvascular plants. T he DER for this study ha s been revised to report the correct 4

- day IC 50

.

DAS Comment # 6 : Additional data are provided to calculate the NOAEL for terrestrial plants

DAS notes that a footnote to Table 17 states that the EPA was not able to calculate the NOAEL for a

non

- guideline seedling emergence study (MRID 43485801) because the study report did not report summary data for the endpoint at a replicate level. DAS claims t hat replicate data for this endpoint w ere provided in Appendix K of the study report. They have submitted a copy of these data to EPA via mail, and requests that it be used to calculate the NOAEL values. They request that the NOAEL values be

used in the ri sk assessment rather than the EC 05 values.

EFED Response #

6 :

The replicate data provided by DAS allow s EPA to calculate NOAEL values for the seedling emergence study conducted with flumetsulam and four other pesticides (MRID 43485801). T he NOAEL values ar e somewhat higher than the IC 05 values that were used in the risk assessment

. Recalculating the RQs with

the NOAEL values therefore decrease s the RQ values for listed species. It does not affect the RQs calculated for nonlisted plant species, which a re b ased on the IC 25 values. It a lso does not affect results of the calculations done with AgDrift to determine the distance from the edge of the field where the spray drift exposure exceeds the toxicity endpoint. Since that analysis was for spray drift only, it used toxicity results only from the vegetative vigor study, not from this seedling emergenc e study.

The RQs for listed plant species were calculated based on the most sensitive monocot species, sorghum, and the most sensitive dicot species, canola (also called rapeseed )

. Plant weight was the most sensitive endpoint for both species. The new ly c alculated NOAEL and LOAEL values for sorghum and canola, as well as the previously calculated EC 05 values, are given in the table below.5

Species and endpoint NOAEL LOAEL EC 05 Sorghum(monocot), plant weight 0.00223 lb a.i./A (2.5 g a.i. /ha) 0.000568 lb a.i./A (5.0 g a.i. /ha) 0.000568 lb a.i./A

Canola (dicot), plant weight 0.0000697 lb a.i./A (0.0781 g a.i./A) 0.000139 lb a.i./A (0.156 g a.i./A) 0.0000452 lb a.i./A

The new NOAEL values are greater than the IC 05 values by a factor of 3.93 for sorghum a nd by a factor

of 1.54 for rapeseed. Therefore, the listed RQs for listed monocot species decrease by a factor of 3.93

, and the RQs for listed dicot species decrease by a factor of 1.54 . This change is not enough to reduce any of the RQs for listed dicots to below the LOC of 1. For monocot species, the RQ for exposure to listed upland plants from post

- emergence ground applications on soybeans is decreased below the LOC,

while all of the other RQs, including all RQs for wetland species

, still exceed the LOC. Therefore, recalculating the RQs using the NOAEC values in place of the IC 05 values do not change any of the risk conclusions for listed species of plants except for upland monocot species associated with post

emergence use of flumetsulam on soybean. It i s noted, however, that the RQ for preplant/pre

- emergent
use of flumetsulam on soybean is still above the LOC , and thus the overall risk conclusion for listed upland monocots associated with soybeans does not change.

Since the change s in the RQs related to the change of these toxicity endpoints does not alter the overall

risk conclusion for any use site , the preliminary risk assessment document will not be modified based on this change. However, the DER for this study has been revised to include the newly c alculated NOAEC

and LOAEC values

.

DAS Comment # 7 : The assumptions of the TerrPlant Model are unrealistic and overly

- conservative

DAS presents several criticisms of the assumptions used in the TerrPlant model to estimate exposure to

nontarget plants. They propose alternative assumptions and calculations for estimating exposure which they claim are more realistic. They then present results from a modified tier 1 risk assessment for terrestrial plants, and a refined tier 2 risk assessment

EFED Response #7 :

We agree that the TerrPlant Model provides upper bound estimate s of off

- site exposure to terrestrial plants. EFED is currently developing a more refined tier II terrestrial plant exposure model to address

this issue. The comments that DAS su bmitted concerning recommended refinement of the terrestrial plant exposure model have been forwarded to the team developing this new model. However, until this

new model is complete d

, has undergone peer review, and QA/QC review, EFED will continue to rely on

the TerrPlant model for conducting quantitative exposure assessments for risk to nontarget terrestrial plants.6

Comments from Minnesota Department of Agriculture

The Minnesota Department of Agriculture (MDA) submitt ed monitoring data for flumetsulam. Data sets were provided which give results of analysis for flumetsulam residues in samples of surface water and ground water collected in Minnesota during 2011 through 2013. In the surface water monitoring,

flumetsulam w as detected in 7 out of 375 (1.9%) of the samples. Detected flumetsulam concentrations ranged from 0.0508 to 0.101 μg/L. In the ground water monitoring, flumetsulam was detected in 16 out of 600 (2.7%) of the samples. Detected flumetsulam concentrations ra nged from 0.0535 to 0.137 μg/L. The limit of detection for both the surface and ground water analysis was 0.050 μg/L.

EFED Response:

EFED appreciates the MDA making their monitoring data available to us. The information submitted by Minnesota report s th e date of sampling and indicates a relatively low limit of detection, but without information concerning the surrounding land use or pesticide use at or upstream from the monitoring

site , as well as other relevant ancillary data, further analysis is limite d

.

REFERENCES

Bruce, R.D. and D.J. Versteeg. 1992. A statistical procedure for modeling continuous toxicity data.

Environ. Toxicol. Chem. 11:1485

- 1495.