Page 1 of 25 OFFICE OF CHEMICAL SAFETY

ANDPOLLUTION PREVENTION UNITED STATES ENVIRONMENTAL PROTECTION AGENCY

WASHINGTON D.C., 20460

PC Code: 035201

DP Barcode s : 424259 , 426211, and 427439

MEMORANDUM

DATE: September 10 , 2015

SUBJECT: Response to Comments Submitted to the Dicrotophos Registration Review

Docket (Docket ID: EPA

- HQ

- OPP

- 2008

- 0 440 ) and Addendum to the Dicrotophos Preliminary Ecological Risk Assessment

TO: Khue Nguyen

, Chemical Review Manager

Neil Anderson

, Branch Chief Risk Management and Implementation Branch I

Pesticide Re

- Evaluation Division (7508P)

FROM: Nathan Miller , Biologist

Andrew Shelby, Physical scientist

Environmental Risk Branch VI

Environmental Fate and Effects Division (7507 P )

Through: Mark Corbin, Branch Chief

Monica Wait, Risk Assessment Process Leader

Environmental Risk Branch VI Environmental Fate and Effects Division (7507 P )

In response to the “ Transmittal of the Preliminary Environmental Fate and Ecological Risk Assessment for the Registration of Dicrotophos ” (Document ID EPA

- HQ

- OPP

- 2008

- 0440

- 0022

in www.regulations.gov

, DP 393746, 7/10/2014 ), AMVAC Chemical Company (“AMVAC”) provided comments during the public comment period. The purpose of this memorand um is to

address those comments and respond to technical/science

- related questions and comments as they pertain to the preliminary risk assessment d ocument.

Additionally, the Environmental Fate and Effects Division ( EFED ) explored the impact of typical application rates

— as described in a m emorandum from the Biological and Economic Analysis Division ( Mallampalli and Becker, 2014)

— on risk conclusions

. A ssuming typical application rates and retreatment intervals, estimated environmental concentrations (EECs) are reduced by approximately 50%; however, risk quotients (RQs) still exceed the level of concern (LOC) for all taxa identified as having RQs exceeding the LOC in the preliminary risk

assessment , albeit at a lesser magnitude ( see Appendix A ).Page 2 of 25

AMVAC Comment: Section 3.2.1. Selection of Screening

- level Effects Metrics, Birds and Mammals; PDF Page s 55 & 56

- Avian acute oral study select ion : A closer review of the selected acute effect metric for domestic goose used in the assessment suggests that there are many deficiencies in the study (Doyle and Elsea (1963)) [MRID 00013439]

... As a result, this study is insufficient in terms of data reporting in accordance with OPP's evaluation guidelines (EPA, 2011a)

... Further, a more recent literature study on starlings provides a better basis for calculating dose

- based dietary risk (Grue and Shipley, 1984).

EFED Response: EFED concurs with AMVAC that MRID 00013439 is insufficient in terms of data reporting to be used quantitatively in risk assessment. A table of the avian acute oral toxicity studies available for dicrotophos can be found on page 15 (PDF page 17)

of the October 28, 1998 EFED RED C hapter for Dicrotophos (Document ID EPA

- HQ

- OPP

2008

- 0440

- 0009 ) . The 1984 Grue and Shipley study referenced in the AMVAC comment is cited on page 16 (PDF page 18) in Table 4 of the EFED RED chapter. California quail were

the most sensitive avian species i n acute oral toxicity studies and the LD 50 of 1.51 mg/kg

- bw from this study, classified acceptable, is now used for risk estimation ( Table 1 )

. The T

- REX

acute avian dose

- based risk quotients using the California quail LD 50 (bodyweight treated as northern bobwhite) are presented in Table 1

. These tabulated RQs were derived using the dicrotophos

- specific Mineau scaling factor of 1.118 (a default scaling factor of 1.15 was inadvertently used in the T

- REX calculations for the p reliminary risk assessment). RQs presented in Table 1 are approximately half as large as the RQs that were presented in Table

4.9 (Page 52) of the dicrotophos preliminary risk assessment for registration review (DP 393746, 7/10/2014)

.

Table 1 . Upper Boun d Kenaga, Acute Avian Dose

- Based Risk Quotients

Size

Class (grams) Adjusted

LD 50 EECs and RQs

Short Grass Tall Grass Broadleaf

Plants Fruits/Pods/Seeds Arthropods Granivore

EEC RQ EEC RQ EEC RQ EEC RQ EEC RQ EEC RQ

20 1.17 240.24 205.92 110.11 94.38 135.14 115.83 15.02 12.87 94.10 80.65 3.34 2.86

100 1.41 137.00 97.11 62.79 44.51 77.06 54.63 8.56 6.07 53.66 38.04 1.90 1.35

1000 1.85 61.34 33.13 28.11 15.19 34.50 18.64 3.83 2.07 24.02 12.98 0.85 0.46Page 3 of 2 5

AMVAC Comment: Section 3.2.1. Selection of Screening

- level Effects Metrics, Birds and Mammals; PDF Page 56

- Avian s ub acute dietary study selection : EPA (2014) also presented risk results based on dietary exposures. Typical guideline acute dietary studies have a five day exposure period followe d by three days of observation. However, the toxicity study selected by EPA (2014) was actually 28 days in length.

EFED Response: EFED concurs with AMVAC that the exposure duration of MRID 00013707 limits the utility of this study for quantitative use in risk assessment. A table of the avian subacute dietary toxicity studies available for dicrotophos can be found on page 17 (PDF page 19) of the October 28, 1998 EFED RED Chapter for Dicroto phos (Document ID

EPA

- HQ

- OPP

- 2008

- 0440

- 0009 ) . Japanese quail were the most sensitive avian species in subacute dietary toxicity studies and the LC 50 of 32 mg/kg

- diet from this study, classified supplemental, is now used for risk estimation ( Table 2 )

. The 2014 EFED PRA (DP 393746, 7/10/2014) found RQs to range from 1.01 (dietary items : fruits/pods/seeds) to 16.23 (short grass) . Using the LC 50 of 32 mg/kg

- diet results in slightly lower RQs ranging from 0.41 (dietary items : fruits/pods/seeds) to 6.59 (short grass)

.

Table 2 . Upper Bound Kenaga, Subacute Avian Dietary Based Risk Quotients

LC 50 EECs and RQs

Short Grass Tall Grass Broadleaf

Plants Fruits/Pods/Seeds Arthropods

EEC RQ EEC RQ EEC RQ EEC RQ EEC RQ

32 210.94 6.59 96.68 3.02 118.66 3.71 13.18 0.41 82.62 2.58

AMVAC Comment: Section 3. 2.1. Selection of Screening

- level Effects Metrics, Birds and Mammals; PDF Page 56

- Avian chronic study end points: For chronic exposure, EPA (2014) used the NOEC (1 ppm) from a mallard duck reproduction study. The NOEC was based on an 8% reduction in female body weight at the next highest treatment level (3 ppm). However, an 8% reduction in female body weight should not be considered ecologically relevant as such small changes would reflect natural variab ility. Certainly, minor reductions in body weight in the laboratory are unlikely to be realized in the field as birds are mobile and will spatially average their daily exposure. These minor effects on body weight are unlikely to result in population level effects particularly as dicrotophos is applied only twice a year within 14 days for crop protection, and recovery from acetylcholinesterase (AChE) inhibition tends to be rapid (Fleming et al. 1981; Fleming and Grue, 1981).

EFED Response: The selection of the NOAEC in the mallard reproduction study was based on a statistically significant reduction in bodyweight. EFED reviews ecotoxicological studies for effects to the apical endpoints of survival, growth, and reproduction

. A weight effec t is a growth effect that could adversely affect survival in the wild.

AMVAC Comment: Section 3.2.1. T

- REX ; PDF Page 63 : The dislodgeable foliar residue data that are available to the Agency demonstrates that residues decline with a half

- lifePage 4 of 25

established at two different field sites of less than 2.33 days (Prochaska, 1978) [MRID 44728501]. It is recognized that these data do not account for the possibility of a different decline profile for residues that are not dislodged. Therefore, relative a bundance of surface based residues versus residues within the target plant system is not clearly understood. In spite of a lack of certain information, EPA's designation of a 35

- day foliar half

- life for modeling purposes is likely to be highly exaggerated.

EFED Response: EFED will consider any data on foliar half

- life that AMVAC makes available to support an alternative to the 35

- day default foliar half

- life used to parameterize

the T

- REX model. EFED concurs with AMVAC’s evaluation of the limitation of t he available dislodgeable foliar residue study for half

- life estimation.

AMVAC Transmittal Memo Comment # 1 , PDF Page 7 2 : While EPA has identified possible chronic risks of concerns, they are based on a screening level assessment and AMV AC has

herein provided a more refined analysis.

EFED Response: EFED will consider AMVAC’s comments in future refinements to the dicrotophos ecological risk assessment.

AMVAC Transmittal Memo Comment # 2 , PDF Page 7 2 : The study that we believe EPA is referring to is t itled, "Dicrotophos and Monocrotophos in Dislodgeable Foliar Residues on

Cotton Leave s" and is indexed under MRID 44 731002. Our interpretation of this study is that it validates our view that monocrotophos is only a very low level foliar metabolite that is rapidly degraded in the environment and therefore has a very negligible effect on any risk assessments. This study was composed of two field sites and at the site located in Washington County, Mississippi. Detectable levels of monocrotophos were only meas ured at two sampling intervals. The first finding was on the day of the 2 nd application for which the arithmetic mean monocrotophos residue level was less than the limit of quantification. The second finding was 4 days after the 3rd application for which t he arithmetic mean monocrotophos residue level was 0.0145 ppm, less than 2X the limit of quantitation

. Because the highest total residues occurred immediately following each application, the contribution of monocrotophos during these periods is negligible. Also, the labile nature of the monocrotophos residues would not support a contention that the enhanced activity of monocrotophos residues relative to dicrotophos residues would extend the time of acute risk LOC exceedances in a meaningful way, given the s ignificant differences in concentration between parent and metabolite.

EFED Response: It is agreed that monocrotophos is likely a minor foliar degradation product based on the cited study but two samples in one study do not represent a robust

dataset and cannot provide conclusive characterization on the magnitude of monocrotophos as a degradate of dicrotophosPage 5 of 25

AMVAC Transmittal Memo Comment # 3 , PDF Page 7 3 : As the ecological risk assessments are envisioned to be refined over time, it would be clearer to indicate when a risk table was developed using screening

- level modeling and when a refined approach is used. On this basis,

we propose that the title be changed to, "Screening

- Level Risk Resulting from Dicrotophos Exposure Presented by Taxon".

EFED Response: It is agreed that the title proposed by AMVAC is more accurate and clear.

AMVAC Comment # 1 , PDF Page 7 3: Although the butanamide degradates SD 6167 or SD 11733 may pose some undetermined level of risk to certain aquatic species, these chemica ls belong to a class of compounds that is distinct from the organophosphates. On this basis, these two metabolites should not be included in the aquatic risk assessment for dicrotophos.

EFED Response : It is agreed that these degradates may represent different modes of action than parent dicrotophos. However, toxicity may be similar for taxa where AChE inhibition is not the toxicity pathway of concern ( e.g. , plants). Differences between parent

- only and total toxic residues ( TTR ) estimated environment al concentrations ( EECs ) were demonstrated to be too small to impact risk conclusions on any taxa. For the purposes of risk assessment, it is useful to demonstrate the impact of uncertainties that do not impact risk conclusions so that

efforts can be conc entrated on uncertainties that weigh more heavily on risk conclusions.

AMVAC Comment # 2 , PDF Page 7 3 : When discussing the metabolism or degradation of dicrotophos in the context of SD 6167 and SD 11733 formation, it should be clarified that these compounds are not organophosphates. One suggestion is to describe the metabolites as the oxo

butanamide SD 6167 and the hydroxy

- butanamide SD 11733.

EFED Response: Chemical structures are provided in the risk assessment that show the

differences between dicrotophos and degradates.

AMVAC Comment #3, PDF Page 74: The concentration of bifenthrin in product mixes is generally low and its contribution to the overall toxicity to aquatic invertebrates is uncertain. Generally, pesticide mixtures act in an addit ive fashion (NAS, 2013; Rodney et al. 2013) thus there is little reason to believe toxicity would be enhanced beyond what would be expected by an additive response.

EFED Response: EFED agrees that the overall toxicity of these product mixtures are

uncertain.

AMVAC Comment # 4 , PDF Page 74: For a screening level assessment, this approach may be appropriate; however, for a refined assessment, a more accurate assessment would consider the

oxo

- butanamide SD 6167 and the hydroxy

- butanamide SD 11733, se parately. For that reason, itPage 6 of 25

would be appropriate to add an additional statement such as, "Because the oxo

- butanamide SD 6167 and the hydroxy

- butanamide SD 11733 are butanamides and not organophosphates, and should not be included in the dicrotophos risk assessment.

EFED Response: It is agreed that these degradates may represent different modes of action than parent dicrotophos. However, toxicity may be similar for taxa where AChE inhibition is not the toxicity pathway of concern ( e.g. , plants). Differences between parent

- only and TTR EECs were demonstrated to be too small to impact risk conclusions on any taxa. For the purposes of risk assessment, it is useful to demonstrate the impact of uncertainties that do not impact risk conclusions so that efforts can be concentrated on uncertainties that weigh more heavily on risk conclusions.

AMVAC Comment #5 , PDF Page 74: In the absence of toxicity data for terrestrial

- phase amphibians and reptiles, it is standard practice to use endpoints for avian sp ecies as a surrogate (EPA, 2008a). This extrapolation has little, if any, empirical support. That is, the extrapolation is made out of necessity due to a paucity of herptile toxicity data, not because of scientific justification. Birds and herptiles belong to different taxonomic classes, and therefore, have different metabolic rates, diets, respiratory and reproductive systems and ecology in general. Many of these factors can be addressed using a more appropriate exposure model (T

- HERPS) that can account fo r the lower metabolic rates and thus lower food and residue ingestion experienced by a herptile in the field.

EFED Response : Acute dose

- based RQs for three size classes of herptile were calculated using T

- HERPS to explore the magnitude of reduction in EECs and RQs for three size

classes of herptiles compared to the RQs determined for avian species using T

- REX (Tables 3 & 4)

. Whereas the T

- REX calculated RQs for a 20 gram bird range from 0.46 to 205.92,

T

- HERPS parameterized with the same avian LD 50 and application information used in T

REX calculated a range of RQs from 0.37 to 120.98 for a 20 gram amphibian

.

Table 3 . Upper Bound Kenaga, Acute Herptile Dose

- Based EECs

Dose

- based EECs (mg/kg

- bw) Herpetofaunal Size Classes and Body Weights

small (g) mid (g) large (g)

2 20 200

Short Grass 11.72 6.95 4.12

Tall Grass 5.37 3.18 1.89 Broadleaf plants/sm Insects 6.59 3.91 2.32

Fruits/pods/seeds/lg insects 0.73 0.43 0.26

Herbivore mammals 385.18 141.14 51.72

Insectivore mammals 24.07 8.82 3.23

Reptile/Terrestrial phase amphibian 4.82 2.86 1.69Page 7 of 25

Table 4 . Upper Bound Kenaga, Acute Herptile Dose

- Based Risk Quotients

Dose

- based RQs (Dose

- based EEC/adjusted LD 50 ) * Amphibian/Reptile Acute RQs for Small, Medium, and Large Species (grams)

2 20 200

Short Grass 13.18 5.95 2.69

Tall Grass 6.04 2.73 1.23 Broadleaf plants/sm insects 7.41 3.35 1.51 Fruits/pods/seeds/lg insects 0.82 0.37 0.17

Herbivore mammals 433.22 120.98 33.78

Insectivore mammals 27.08 7.56 2.11 Terrestrial phase amphibian 5.42 2.45 1.11

*LD 50 of 1.51 mg/kg

- bw from California quail

AMVAC Comment #6 , PDF Page 74: As discussed in Section 2.3.4 of this report, the SIP model is extremely conservative and does not consider dissipation kinetics, application rates,

chronic exposure durations, application timing (on days without precipitation events), mammalian and avian mobility, and other factors that would result in a significantly more realistic exposure scenario. AMVAC recommends that the Agency re

- evaluate the use of SIP even at the screening level, and conduct a more reasonable, realistic drinking water assessment for all pesticide products.

EFED Response: SIP is not a risk assessment tool. EFED uses the SIP model as a screen at the problem formulation stage to det ermine whether additional consideration should be given to the drinking water exposure route.

AMVAC Comment # 7 , PDF Page 7 5 : It is recognized that there is very limited background

data concerning the cause of the peak detection in wate r of 6.83 ppb. As this value is significantly out of range of other reported values, it remains a distinct possibility that the finding represents some aberration as opposed t o a true value. A more thorough assessment of the NAWQA data set is contained w it hin AMVAC's response to EPA's assessment of water exposure and aggregate risk.

EFED Response : The peak detection of 6.83 ppb for dicrotophos is not an aberration when considered in the context of organophosphates with similar environmental fate propertie s ( i.e., short metabolic half

- lives) but more NAWQA monitoring data. Of more than 62,000 samples for malathion, six samples had detections between 6 ppb and 22.5 ppb. Much like dicrotophos, it was found that detections were below one part per billion on days immediately following peak detections of malathion. NAWQA currently contains 8,831 samples for dicrotophos . Given that there is one detection above 6 ppb for every 10,000 malathion samples, it is not unreasonable that there is only one dicrotophos d etection at this

concentration. Single maximum application rates for agricultural uses of malathion rangePage 8 of 25

from 0.5 to 7.5 lbs a.i./A as compared to the dicrotophos rate of 0.5 lb a.i./A on cotton. Malathion is used as an example because it has a similar short half

- life and also has a large

non

- targeted monitoring dataset. Additionally, areas of high dicrotophos usage, such as northwest Texas, have no reported NAWQA surface water monitoring samples for dicrotophos.

AMVAC Comment #8 , PDF Page 7 5 : Soil dissipation studies do n ot provide evidence of

residues occurring at lower soil depths. Also, the EP A has demonstrated through PRZM

- GW modeling that there is little exposure potential for dicrotophos within groundwater.

EFED Response: It is concluded that the terrestrial field dissipation study (MRID 41114301) does not address the formation and decline of degradates. However , PRZM

- GW estimates provided in the revised DWA indicate groundwater is not a substantial exposure pathway

.

AMVAC Comment #9 , PDF Page 7 5 : Information concerning the iden tity of the compounds

should be provided in the text. As previously stated, SD 6167 is better described as the

oxobutanamide SD 6167 and SD 11733 as the hydrox y

- butanamide.

EFED Response: AMVAC’s naming preferences will be incorporated in future risk

assessments.

AMVAC Comment #10

, PDF Page 76 : AMVAC Chemical Corporation has labeling provisions

that prescribes certain drift reduction technology (DRT) measures and would seek that the effect of such mitigation be incorporated into the risk assessment. For example, on this basis, the default ASAE Fine to Medium droplet size distribution should be modified to a coarser droplet

size.

EFED Response: Incorporation of DRT measures on dicrotophos labels is good; however, these labels do not appear to have the specificity to support modifying the risk assessment assumptions as claim ed by this AMVAC comment.

AMVAC Comment #11

, PDF Page 76 : Information concerning the low potential for monocrotophos to be formed on foliage surface is evident based on the foliar residue study titled, "Dicrotophos and Monocrotophos in Dislodgeable Foliar Residues on Cotton Leaves" and filed

under MRID 44 731002. The study de monstrates that residues of monocrotophos on cotton foliage at two distinct sites remained at very low levels over a 35 day period after 3 applications. On this basis, the words, "in and/or on foliage" should be modified to "in foliage".

EFED Response: T he language change could be made but does not substantially change the meaning of the statement.Page 9 of 25

AMVAC Comment #12

, PDF Page 76 : EPA's Preliminary Environmental Fate and Ecological

Risk Assessment for the Registration of Dicrotophos (Case #145), is not an Endangered Species Assessment, but rather an ERA to evaluate the registration of dicrotophos under

FIFRA.

EFED Response: In November 2013, the EPA, along with the U.S. Fish & Wildlife Service (USFWS), the National Marine Fisheries Service (NMFS) (coll ectively, 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 National Academy of Sciences’ (NAS) recommendations and reflect a common approach to risk assessment shared by the agencies as a way of addressing scientific differences between the EPA and the

Services. The NAS report outlines recommendations on specific scientific and technical issues related to the development of pesticide risk assessments that EPA and the Services must conduct in connection with their obligations under the Endangered Species Act (ESA)

and FIFRA. The joint Interim Approaches were released prior to a stakeholder workshop held on November 15, 2013. In addition, the EPA presented the joint Interim Approaches at

the December 2013 Pesticide Program Dialogue Committee (PPDC) and State

- FIFRA Issues

Research and Evaluation Group ( SFIREG) meetings, and held a stakeholder workshop in April 2014, allowing additional opportunities for stakeholders to comment on the Interim Approaches. As part of a phased, iterative process for developing the Interim Approaches, the agencies will also consider public comments on the Interim Approaches in connection with the development of upcoming Registration Review decisions. 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.

Given that the agencies are continuing to develop and work toward implementation of the Interim Approaches to assess the potential risks of pesticides to listed species and their designated critical habitat, this preliminary risk assessment for dicrotophos does not contain a complete ESA analysis. While the agencies continue to develop a common method for ESA analysis, this preliminary, screening

- level risk assessment indicates potential risks of direct effects to listed freshwater and estuarine/marine invertebrates, mammals, birds, and

terrestrial invertebrates from the use of dicrotophos on some of its registered use sites. Listed species of freshwater and estuarine/marine invertebrates, mammals, birds, and terrestrial invertebrates may also be affected through indirect effects bec ause of the potential direct

effects on listed and non

- listed species. Potential direct effects on listed freshwater and estuarine/marine invertebrates, mammals, birds, and terrestrial invertebrates from the use of dicrotophos may be associated with modif ication of Primary Constituent Elements (PCEs) of designated critical habitats, where such designations have been made. Once the agencies have fully vetted the scientific methods necessary to complete risk assessments for endangered and threatened (listed ) species and their designated critical habitats, these methods will be applied to subsequent analyses for dicrotophos as part of completing this registration review.Page 10 of 25

To conduct full ESA analysis for individual listed species, useful refinements may inc lude, but are not limited to, analyses of: 1) more detailed, species

- specific ecological and biological data; 2) more detailed and accurate information on cotton and tree injection use patterns; and 3) sub

- county level spatial proximity data on the co

- occu rrence of potential effects areas and listed species and any designated critical habitat.

AMVAC Comment #13

, PDF Page 76 : It is not clear whether EPA intended to list the NOEAC

and LOEAC for reproductive effects, which are 0.0028 and 0.0044 mg ai/L, respectively. With respect to length measurements, the NOAEC and LOAEC are 0.00099 and 0.0017 mg ai/L, respectively. However, the length data do not indicate any trend in effect versus concentration; thus we would conclude are not appropriate endpoints for consideration.

EFED Response: In an addendum dated August 27, 2014, EFED upgraded the classification of the data evaluation record (DER) for MRID 44956501 from supplemental to acceptable. In order to review the study data supplement submitted by the contract laboratory, EFED analyzed the data for all study endpoints ( e.g. , leng th, weight, parental survival, offspring per parent, time to first brood) using the Divis i on’s current statistical analysis software (CETIS TM ) and Divisional policy ( e.g ., treatment response was compared to the negative

control instead of the solvent or pooled control)

. It was determined that dry weight and total length were the most sensitive study parameters, with NOAEC and LOAEC values of 1.7 and 2.8 μg a.i./L , respectively

.

AMVAC Comment #14

, PDF Page 77 : W e propose that the reproduction

- based NOAEC and LOAEC be utilized for risk assessment purposes.

EFED Response: EFED policy is to use the most sensitive endpoint from among the apical response endpoints of survival, growth, or reproduction. It was determined that dry weight and total length were the most sensitive endpoints in the study, with NOAEC and LOAEC values of 1.7 and 2.8 μg a.i./L, respectively.

AMVAC Comment #15

, PDF Page 77 : Even for the individual avian species of highest residues, the measured internal dose level did not exce ed the laboratory

- based LD 5 0 of 3 mg/ kg/b w associated with the House sparrow (Passer domesticus), another passerine species.

There is no data to suggest that an external dose of this magnitude would have a detrimental effect on avian species. This data indicates that this exposure level would not place this avian species at undue risk. Sample identification is contained within Table 7 of the report and

indicates that the sample consisted of skin and feathers. The efficiency of transfer of residues

associ ated with the feathers onto the skin is likely not high and the range of concentration

associated with samples having measured internal residues is consistent with that view. In the sample in question that had external residues of 17 ppm, the concentration of residues in the associated carcass was only 0.09 ppm. Therefore, there is no evidence that dicrotophos residues having toxicological implications occur at high levels.Page 11 of 25

EFED Response: The fact that the measured internal dose level did not exceed the L D 50 is no basis for disputing the toxicological relevance of the detected dicrotophos residue

concentration to an individual bird since the very definition of the LD 50 is the dose required

to kill 50 percent of a population of test animals ; mortalities are typically recorded at doses

lower than the LD 50

. External c arcass residue concentrations further help to substantiate T

REX modeled field residues. Beyond the toxicological relevance and bioavailability of external residues uncertainty, a separate uncer tainty is whether i nternal residue concentrations may underestimate maximum internal dicrotophos concentrations in the sampled bird since metabolism of dicrotophos may h ave preceded the mortality event

.

AMVAC Comment #16

, PDF Page 77 : We agree with the statement [“ While neither study design is sufficiently robust for quantitative use in risk estimation, anecdotal information contained within the study reports is useful for risk characterization ”] only in that the avian effects due to th e different individual insecticides, including dicrotophos, should be no worse

than that observed in this study. On this basis, one can conclude that the overall effects seen in

both studies are limited.

EFED Response: EFED does not agree that either fie ld study is necessarily representative

of a worst case scenario. These studies were not designed robustly enough or adequately

executed so as to conclude that effects should be no worse than effects observed in the

studies.

AMVAC Comment #17

, PDF Page 78 : Although we do not dispute the EPA's [avian toxicity] classification on the basis of the laboratory studies, the extent of exposure as evident in the two field studies even in view of the complications previously discussed, demonstrate that the

chemic al is not highly toxic in the field where there were only limited mortalities noted.

EFED Response: While EFED risk assessments do rely on multiple lines of evidence, i t is important to note the limitations of the carcass search employed by the study authors which may have resulted in an underestimate of avian mortalities in the field; namely that fields

were not searched for carcasses until 48 hours after application (in accordan ce with the reentry restriction ) and carcass search efficiency trial failures.

AMVAC Comment #18

, PDF Page 78 : AMVAC believes that the chronic risk to aquatic organisms is best assessed by considering the extensive NA WQA monitoring data set, which

substantiates that actual exposure levels would be far lower than that dete rmined from modeling efforts. Therefore, although chronic risk as calculated using baseline PRZM/ EXAMS modeling implies that there is some risk to aquatic organisms, realistic exposures in surface waters

a ssociated with agricultural areas as evident by mon itoring data is very low and would not pose a risk of concern to aquatic organisms.

EFED Response: Use of PRZM/EXAMS modeled EECs to calculate RQs is consistent with

EFED policy. In the case of dicrotophos, monitoring data from Bogue Phalia is of the samePage 12 of 25

magnitude as the modeled EECs for 1

- in

- 10

- year peak exposure

. However, direct comparison of NAWQA monitoring data from waterbodies with variable flow and variable watershed sizes to EECs from the PRZM/EXAMS farm pond should not be made. Dicrotophos monitoring indicates that concentrations may attenuate quickly in flowing waterbodies but it cannot be assumed this attenuation will occur in all environmental, watershed, and usage conditions. The PRZM/EXAMS farm pond is intend ed conservatively represent these conditions and is therefore the best tool for quantitatively assessing chronic risk to aquatic organisms.

AMVAC Comment #19

, PDF Page 78 : Context should be provided on the 23X exceedance factor as this maximum is as a re sult of an exposure scenario that is unlikely to occur in nature (i.e. a 20 g mammal consuming exclusively short grass). This information has been further refined within this document.

AMVAC Comment #20

, PDF Page 78 : [Chronic dose

- based LOC exceedances for mammals have] been further refined within this document.

AMVAC Comment #21

, PDF Page 78 : [Acute dose

- based LOC exceedances for birds have] been further refined within this document.

AMVAC Comment #22

, PDF Page 79 : [Sub

- acute dietary

- based LOC exceedances for birds have] been further refined within this document.

AMVAC Comment #23

, PDF Page 79 : [Chronic LOC exceedances for birds have] been further refined within this document.

EFED Response to AMVAC comments 19

- 23 : EFED will consider AMVAC’s comment s in future refinements to the dicrotophos ecological risk assessment.

AMVAC Comment #24

, PDF Page 79 : No comment

EFED Response: EFED will correct the typographical error in spelling in future dicrotophos ecological risk assessments.

AMVAC Comment #25

, PDF Page 79 : EPA has cited incidents as late as 1976 and has suggested that the weight of the evidence forms a basis for assessing direct ecological effects from the current registered use. However, the current registered use differs from pre vious labels and agricultural practices in many ways. These exposure mitigation changes, some prescribed by EPA, have had a significant impact on reducing environmental concerns related to product use. Further and most importantly, there is no evidence of avian incidents associated with the current registered use on cotton.Page 13 of 25

EFED Response: EFED concurs that there are no incidents recorded in either the Avian Incident Monitoring System or the Ecological Incident Information System associated with the current registered use of dicrotophos on cotton. The absence of incident data cannot be

construed as an absence of incidents resulting from use on cotton , but EFED will consider AMVAC’s comment in future refinements to the dicrotophos ecological risk assessment.

AMVAC Comment #26

, PDF Page 79 : Our understanding is that EPA did not utilize the 90th percentile mean of metabolism half

- life estimates as stated, but in stead added conservatism to

the assessment by incorporating a 3X multiplier to t he single aerobic and anaerobic metabolism half

- lives on file and a 6X factor to the aerobic aquatic metabolism half

- life.

EFED Response: When there is one study, the half

- life is multiplied by 3, i.e., half

- life x 3 = input parameter

. Thi s is viewed as an estimate of the upper bound on the mean that

is calculated under the following assumptions: (a) T he experimental half

- life is the mean value fr om a normally distributed population. (b) T he standard deviation is equa l to the

mea n ( i.e ., coefficient of variation= 100%). (3) The "mean" value times 3 (equivalent to

mean plus 2 standard deviations) r epresents the 90% upper bound

. Th is is almost equivalent to using the value of 3.078 for one degree of freedom (df=l)

. Some experimental justi fication for this approximation is provided by Howard and Howard 1

who extens i ve l y studied soi l respira t ion (carbon evolution) rates i n diverse soi l s with

different microbiologica l activities and about 75% of water holding capacity, the current

EFED soil moistu r e norm. Inspection of their data shows that the temperature

independent ratio of c a rbon dioxide evolution of the most active soil to that of the least active soil was approximately 2.7, or close to 3. In addition, a preliminary data evaluation

for s evera l pesticides suggests that soil metabo l ism half

- l ives vary by about a factor of 3.

AMVAC Comment #27

, PDF Page 80 : We do not dispute the factual nature of the comment; however, the implications of the finding need to be more thorough ly examined. It is important to consider that this single value is not representative of the entire very large NA WQA dataset where residues are more than an order of magnitu de lower for all other samples. A more thorough assessment of the NAWQA data set is contained within AMVAC's response to EPA's assessment of water exposure and aggregate risk.

EFED Response: It is agreed that the single value is not representative of the entire dataset but the dataset is not targeted monitoring data. Non

- targeted monitoring data may provide characterization of pesticide concentrations but lacks sufficient context and sampling timing to capture peaks associated with pesticide usage , especially for a pesticide like dicrotophos

that is demonstrated to differ in conce ntration by more than an order of magnitude from one day to the next. The use of targeted monitoring bias factors presented at Scientific Advisory Panels ( 6/12

- 15/2012; 7/26

- 28/2011, and 4

- 26

- 29/2010 ) were considered but are not appropriate for dicrotopho s’ non

- targeted monitored data. Due to dicrotophos’ short aerobic

metabolism half

- life, malathion chemographs are expected to behave similarly to the “flashy”

1 Howard, D. M., and P. J. A. Howard. "Relationships between CO~ 2 evolution, moisture content and temperature for a range of soil types." Soil Biology and Biochemistry 25 (1993): 1537

- 1537.Page 14 of 25

runoff events with sharp peaks and rapid recessions described in the bias factors SAPs.

These e vents do not allow for robust estimates of bias factors for peak concentrations with sparse, systematic sampling.

AMVAC Comment #28

, PDF Page 80 : The spray drift assessment using AgDrift v 2.01 is

accur ate for use practices that underlie the model when it was deve loped. Since the time when

this data was developed, there have been important adv ances in reducing drift through implementation of more modem, good agricultural pra ctices. For example, changes in nozzle specifications have led to coarser drople ts t hat are less prone to drift. On AMVAC's Bidrin labels are significant instructions to re duce drift and we believe these have dramatically reduced drift. Therefore, the results o f AgDrift overestimate exposure and risk.

EFED Response: The spray drift l anguage on Bidrin labels have been reviewed and the instructions therein are not inconsistent with AgDRIFT parameterizations made in the risk assessment for dicrotophos.

AMVAC Comment #29

, PDF Page 82 : The exposure of aquatic organism s is best reflected by the very large NA WQA dataset, which indicates that exposure lev els in surface water should not be detrimental to aquatic species. The EPA's PRZM/GW modeling assessment is sufficient to demonstrate that exposure associated wit h groundwater sources would not pose a risk to aquatic organisms.

EFED Response: Non

- targeted monitoring is used only for risk characterization and not for risk estimation. Surface water modeling through PRZM/EXAMS or SWCC is principally relied upon for assessing exposure to aquatic taxa.

AMVAC Comment #30

, PDF Page 82 : AMV AC propo ses that the Agency's statement be further clarified by adding information that explains that the AgDrift m odel is based on a dataset

that reflects application practices that have since been refi ned and are included on current product labels; therefore the modeling outputs likely exaggerate actual drift concerns ; but provide a useful screening level assessment.

EFED Response: Current product labels do not make reference to Drift Reduction Technology (DRT) nor have studies been submitted to support DRT for dicrotophos uses. For more information on EPA’s DRT program, please visit the following website: http://www2.epa.gov/reducing

- pesticide

- drift/about

- drift

- reduction

- technology

- program

AMVAC Comment #31

, PDF Page 82 : [Acute LOC exceedances for mammals have] been further refined within this document.

EFED Response: EFED will consider AMVAC’s comment in future refinements to the dicrotophos ecological risk assessment.Page 15 of 25

AMVAC Comment #32

, PDF Pages 82

- 83 : [Dose and dietary

- based chronic LOC

exceedances for mammals have] been further refined within this document. As this assessment addresses reproductive issues that are indicative of population

- based effects, it is worthier noting that the baseline risk assessment itself is derived from the risk to the m ost sensitive individual of a group of animals. The use of the NOAEC is not population

- based as the impact of a small portion of animals is unlikely to cause a detrimental effect to the population as a whole. Therefore, we find that EPA's statement that it believes that there is a high level of confidence in their prediction of adverse chronic effects is overstated. A more appropriate statement would

have been that based on the Agency's risk assessment, it finds that chronic RQs exceed the regulatory standa rds.

EFED Response: EFED concurs with AMVAC that mammalian chronic RQs exceed the
EFED’s established level of concern. EFED will consider AMVAC’s comment in future refinements to the dicrotophos ecological risk assessment.

AMVAC Comment #33

, PDF Page 83 : [Acute LOC exceedances for mammals have] been further refined within this document.

EFED Response: EFED will consider AMVAC’s comment in future refinements to the dicrotophos ecological risk assessment.

AMVAC Comment #34

, PDF Page 83 : As previously stated, the spray drift assessment using AgDrift v 2.01 is accurate for use practices that underlie the model. Since the time when this data was developed, there have been important advances in reducing drift through implementation of more mo dem, good agricultural practices. For example, changes in nozzle specifications have led to coarser droplets that are less prone to drift. On AMVAC's Bidrin labels, these practices are provided to the user and ensure that previous concerns relating to

chem ical drift have been properly mitigated.

EFED Response: Current product labels do not make reference to Drift Reduction Technology (DRT) nor have studies been submitted to support DRT for dicrotophos uses. For more information on EPA’s DRT program, plea se visit the following website: http://www2.epa.gov/reducing

- pesticide

- drift/about

- drift

- reduction

- technology

- program

AMVAC Comment #35

, PDF Page 84 : [ Acute dose

- based, s ub

- acute dietary, and chronic dietary LOC exceedances for birds have] been further refined within this document. Also, it is not clear what the Agency means when it states that there is a high degree of certainty that avian species will be adversely impacted by dicrotophos. As stated earlier, the chronic risk assessment is more geared to wards assessing the impact on individual birds, rather than on the species due to the use of the NOAEC as the toxicological endpoint. Also, we believe that the Agency is overstating its conclusion based on a deterministic, screening level assessment withou t fully examining the supporting evidence (incident reports and field studies).Page 16 of 25

EFED Response: EFED will consider AMVAC’s comment in future refinements to the dicrotophos ecological risk assessment. The risk assessment’s statement about a high degree

of certainty in the prediction of avian risk stems from the magnitude of the RQs which are directly related to the estimated exposure concentrations.

AMVAC Comment #36

, PDF Pages 84

- 85 : [Acute and chronic LOC exceedances for birds have] been further refined within this document. Also, it is important to place into perspective the timing calculated for achieving an acceptable LOC as the shape and slope of the curves have a significant basis on how far the acceptable values extend and relatively small o verages in the RQ values may occur well before the calculated times associated with these values. This is evident for assessing the effect of time on achieving an acceptable chronic LOC in EPA's Figure 4.2 Avian LOCs Superimposed on Residue Decline Curve. It is also important to note that the residue decline curves represent generic upper bound estimates that likely underestimate the rate of residue degradation on food items. It is also worth noting that to properly assess a sophisticated approach for evalu ating the meaning of the time periods associated with RQ exceedances, it is important to consider the likely exposure periods of different species of birds.

EFED Response: EFED will consider AMVAC’s comment in future refinements to the dicrotophos ecolog ical risk assessment.

AMVAC Comment #37

, PDF Page 86 : As previously stated, the use of AgDRIFT is appropriate for a screening level assessment; however, with the implementation of more modem good agricultural practices, appropriate labeling provisions have been developed for dicrotophos products that address these previous concerns relating to drif t associated with outdated application procedures. AMVAC believes that current labeling practices relating to drift fully address environmental exposure issues.

EFED Response: Current product labels do not make reference to Drift Reduction Technology (DR T) nor have studies been submitted to support DRT for dicrotophos uses. For more information on EPA’s DRT program, please visit the following website: http://www2.epa.gov/reducing

- pesticide

- drift/about

- drift

- reduction

- technology

- program

AMVAC Comment #3 8

, PDF Page 86 : AMV AC agrees with the EPA's statement that

inhalation should not be regarded as a primary route of exposure. We also believe that in consideration of all of the information associated with inhalation exposure, especially the changes in application to minimize any fine aerosol spray droplets

, that it is appropriate to characterize inhalation exposure as an unlikely route of exposure concern.

EFED Response : EFED will consider AMVAC’s comment in future refinements to the dicrotophos ecolo gical risk assessment, but any changes to the inhalation exposure component of the conceptual model will need to be based on explicit nozzle and droplet size restrictions specified on the label.Page 17 of 25

AMVAC Comment #39

, PDF Page 86 : AMVAC believes that although there is always some value for developing additional information, there is already sufficient evidence that dicrotophos use on cotton does not yield environmental incidents on honey bees nor is there data to indicate any exposure. The Bidrin label also calls for care in terms of not utilizing the product when bees are detected in the fields designated for treatment. Also, consideration of dislodgeable foliar residue data on cotton as previously described in this document provides evidence to suppor t the contention that dicrotophos residues are not persistent on foliage.

EFED Response : T he Agency has issued guidance for the data needed to assess pesticide risk to bees (USEPA et al. , 2014). This guidance document indicates that if exposure of bees to a pesticide is expected 2 , a Tier I screening

- level risk assessment is conducted. The Tier I assessment is intended to be sufficiently conservative that chemicals that pass the screen are considered to represent a relatively low risk of adverse effects to bees. Tier I toxicity data that are generally needed to complete screening

- level risk assessments include:

 acute contact toxicity data to adult honey bees (honey bees serving as a surrogate for all bee species)

 acute and chronic oral toxicity to adult honey bees

 acute and chronic oral toxicity to juvenile ( i.e. larval) honey bees.

If risk concerns are identified in the screening

- level assessment, it may be refined using data that further define exposure or through additional data including Tier II se mi

- field or Tier III

full

- field toxicity tests.

The use of dicrotophos on cotton include ground and aerial applications where spray drift may land on blooming non

- target plants and could result in residues in pollen and nectar (which could then be transpo rted to the hive). Residues can in turn be brought back to bee

colonies where in

- hive bees including young adult and developing brood ( i.e. , eggs, larvae and pupae) may be exposed. Therefore, exposure at all bee life stages would be expected.

Since e xposure of bees to dicrotophos residues is expected, Tier I honey bee laboratory toxicity data are needed to conduct a screening

- level risk assessment. Acute contact toxicity

data is available that indicates dicrotophos residues are highly toxic to honey bees on an acute contact basis. However, no data are available that evaluate dicrotophos ’ toxicity from the oral exposure route to adult bees on a chronic basis and larval bees on an acute or chronic

basis.

Therefore, the Agency is requesting Tier I laboratory toxicity data for acute and chronic oral toxicity for larval honey bees and chronic oral toxicity to adult honey bees in order to complete the screening

- level risk assessment for bees. Should the scre ening level risk assessment identify that there are risk concerns to bees, mitigation measures may need to be

2 Exposure is expected for the cotton use because bees are required for crop pollination ( Delaplane and Mayer

, Crop P ollination by B ees ) and exposure is presumed for the tree injection

use on pollinator

- attractive treesPage 18 of 25

considered and/or the registrant may need to conduct Tier II or III effects studies that reduce uncertainty by characterizing dicrotophos’ effects at the whole

- colony level.

AMVAC Comment #40

, PDF Page 86 : As EPA has determined that the acute risk to freshwater and estuarine/marine fish is not of concern and that the chronic risk quotients for freshwater fish are all less than 0.001, the developme nt of additional chronic data for the refinement of risk to estuarine/marine species is not warranted.

EFED Response : The chronic toxicity of dicrotophos to estuarine/marine fish is a risk assessment uncertainty that can only be resolved through the submission of additional data.

AMVAC Comment #41

, PDF Page s 86

- 87 : AMVAC recognizes the current variability in the approach and proposed methods for the conduct of National Endangered Species Assessments for pesticide products. In 2012, the Services and EPA asked the National Academy of Sciences (NAS) to address several areas of concern with regard to how pesticide risk assessments are conducted by EPA and the Services. In the 2013 report entitled "Assessing Risks to Endangered and Threatened Species from Pesticides" (NAS, 2013), NAS provided a proposed framework for conducting generic endangered species assessments under FIFRA with direct consideration of the ESA Section 7 requirement (Figure 1). In addition, the NAS panel recommended the use of refined a pproaches (e.g., probabilistic methods, population modeling) when conducting risk assessments for endangered species. The EPA, Services and USDA are currently evaluating the

NAS panel report and are providing fairly regular updates on progress (e.g. Federal Family, 2013; EPA, 2013; EPA, 2014a; EPA, 2014b).

One comment on the Agency's description of the process relates to the use of endangered sp ecies LOCs (Section 6.2

- 3rd pp ). The NAS report recommended strongly against the use of LOCs, favoring pro babilistic approaches (NAS, 2013). The Agency and Services initially responded with a recommendation of use of a one

- in

- a

- million analysis as described in the Interim Approach. Thus, use of endangered species LOCs is unlikely in the process at this time.

R ecognizing the on

- going uncertainty in the ESA process for pesticides, Intrinsik and AMV AC will monitor progress in this area and will provide appropriate input as required to support dicrotophos.

EFED Response : EFED’s methodology for listed threatened a nd endangered species risk assessment continues to evolve in collaboration with various stakeholders. EFED encourages

AMVAC and Intrinsik to participate in the comment period for the three NAS pilot chemical risk assessments, particularly since the three pilot chemicals (c hlorpyrifos, diazinon, and malathion) are organophosphate insecticides.

AMVAC Comment #42

, PDF Page 87 : The Agency was not consistent in the application of the

Mineau scaling factor for dicrotophos of 1.118 for birds in this analysis, but used the default

1.15 for birds in the T

- REX analysis (Appendix C

- Table C

- 2). It is recommended that no scaling factor be applied for birds and dicrotophos.Page 19 of 25

EFED Response : The Mineau scaling factor of 1.15 was inadvertently not modified to
reflect the chemical specific factor of 1.118 available for dicrotophos in the T

- REX model

. RQs associated with the 1.118 scaling factor are slightly lower than the RQs associated with the 1.15 scaling factor

.

AMVAC Appendix 4

ABC Laboratories Comment

, PDF Page 111 : T he reviewer classified [MRID 48482901 ] as SUPPLEMENTAL. However, the inadvertent mingling of fish from two closely linked control replicates early in the study did not result in any trend or effect on sensitive test endpoints determined at study termination. The EPA reviewer determined that this inadvertent mingling of fish from two control replicates early in the study did not impact study integrity. The few edematous fish observed on or before day 0 of the post

- hatch period were not observed at any later time points, and specifically, no edematous fish were observed at test termination, so no edematous fish affected the body weight measurements taken at test termination. Therefore, ABC Laboratories, based on the information provided, believe tha t the study classification should be upgraded to a CORE classification.

EFED Response : EFED has considered ABC laboratories’ comment requesting a change to the study classification for MRID 48482901 but maintains that the supplemental

classification is a ppropriate. While noting that MRID 48482901 does provide information useful for risk assessment and a new study is not requested , EFED concluded in the transmittal memo dated March 20, 2014 that t he redistribution of fry in control replicates is a violation of independence of replicates and calls the integrity of the study conduct into question

. EPA concurs that edema effects observed no later than study day five would not be expected to affect the weight s recorded at study termination; however, dr y weight

measurement is still preferable to wet weight (blotted dry) measurement as stated in the Draft OPPTS 850.1400 guideline.

Response to study classification rebuttal, DP 426211 , MRID: 49527901

EFED has reviewed AMVAC’s response to the study clas sification assigned to a Tier I seedling emergence DER for dicrotophos (MRID 48482902) but maintains that dicrotophos’ mobility, in conjunction with the study’s top

- watering regimen, makes the true dicrotophos exposure level uncertain for the plants tested in the study. EFED therefore considers the previously assigned supplemental study classification appropriate. As stated in the transmittal memo for MRID 48482902, this study is classified supplemental but a new seedling emergence study is not requested since MRID 48482902 contains useful information for the purposes of risk assessment. The nominal concentrations of dicrotophos applied in the available study (MRID 48482902) arePage 20 of 25

treated as estimates of exposure for the purposes of risk assessment; however , the distribution and availability of dicrotophos within the soil of the treated pots after the pots were top

- watered

remains uncertain.

References:

Delaplane and Mayer

, 2000. Crop Pollination by Bees

. CABI Publishing, New York.

Mallampalli, Nikhil and Jonathan Becker , 2014. Information to Support Registration Review of Dicrotophos: Cotton Crop Phenology in the Southern U.S., Recent Dicrotophos Use Patterns,

and Potential Alternative Insecticides. Memorandum from the Biological and Economic Analysi s Division, Office of Pesticide Programs. September 15, 2014.

USEPA, PMRA and CDPR, 2014. Guidance for Assessing Pesticide Risks to Bees. Office of Pesticide Programs, USEPA, Washington D.C. Health Canada Pest Management Regulatory Agency, Ottawa, ON, Canada. California Department of Pesticide Regulation, Sacramento, CA. June 23, 2014.Page 21 of 25 Appendix A

Aquatic risk:

Aquatic estimated environmental concentrations (EECs) are reduced by approximately 50% when the typical application rates, dates, and interv als are modeled. However, all freshwater and

estuarine/marine invertebrate acute and chronic RQs still exceed the Agency’s LOCs under the alternative application assumptions.

Terrestrial risk:

Terrestrial EECs are similarly reduced by approximately 50% when the typical application rates, dates, and intervals are modeled. However, all avian and mammalian acute and chronic RQs (with the exception of acute dose

- based mammalian granivores) still exceed the Agency’s LOCs under the alternative application as sumptions. A 50% reduction in EECs does not alter the risk

conclusion s for terrestrial invertebrates.

Figure 1. TREX parameterization for typical dicrotophos application to cotton , as defined by BEAD’s September

2014 memoPage 22 of 25

Figure 2. Dicrotophos ecotoxicity endpoints used to parameterize TREX modelPage 23 of 25

Summary of Risk Quotient Calculations Based on Upper Bound Kenaga EECs

Table A

- 1 . Upper Bound Kenaga, Acute Avian Dose

- Based Risk Quotients

Size

Class (grams) Adjusted

LD50 EECs and RQs

Short Grass Tall Grass Broadleaf Plants Fruits/Pods/Seeds Arthropods Granivore

EEC RQ EEC RQ EEC RQ EEC RQ EEC RQ EEC RQ

20 1.09 118.78 109.19 54.44 50.05 66.82 61.42 7.42 6.82 46.52 42.77 1.65 1.52

100 1.38 67.74 48.91 31.05 22.42 38.10 27.51 4.23 3.06 26.53 19.16 0.94 0.68

1000 1.96 30.33 15.50 13.90 7.11 17.06 8.72 1.90 0.97 11.88 6.07 0.42 0.22

Table A

- 2 . Upper Bound Kenaga, Subacute Avian Dietary Based Risk Quotients

LC50 EECs and RQs

Short Grass Tall Grass Broadleaf

Plants Fruits/Pods/Seeds Arthropods

EEC RQ EEC RQ EEC RQ EEC RQ EEC RQ

32 104.30 3 .26 47.80 1.49 58.67 1.83 6.52 0.20 40.85 1.28

Size class not used for dietary risk quotientsPage 24 of 25 Table A

- 3 . Upper Bound Kenaga, Chronic Avian Dietary Based Risk Quotients

NOAEC (ppm) EECs and RQs

Short Grass Tall Grass Broadleaf

Plants Fruits/Pods/Seeds Arthropods

EEC RQ EEC RQ EEC RQ EEC RQ EEC RQ

1 104.30 20 8.59 47.80 95.61 58.67 117.33 6.52 13.04 40.85 81.70

Size class not used for dietary risk quotients

Table A

- 4 . Upper Bound Kenaga, Acute Mammalian Dose

- Based Risk Quotients

Size

Class (grams) Adjusted

LD50 EECs and RQs

Short Grass Tall Grass Broadleaf Plants Fruits/Pods/Seeds Arthropods Granivore

EEC RQ EEC RQ EEC RQ EEC RQ EEC RQ EEC RQ

15 17.58 99.44 5.66 45.58 2.59 55.93 3.18 6.21 0.35 38.9472 2.2151 1.3811 0.0785

35 14.23 68.73 4.83 31.50 2.21 38.66 2.72 4.30 0.30 26.9177 1.8921 0.9545 0.0671

1000 6.15 15.93 2.59 7.30 1.19 8.96 1.46 1.00 0.16 6.24096 1.0142 0.2213 0.036Page 25 of 25 Table A

- 5 . Upper Bound Kenaga, Chronic Mammalian Dietary Based Risk Quotients

NOAEC (ppm) EECs and RQs

Short Grass Tall Grass Broadleaf

Plants Fruits/Pods/Seeds/Large

Insects Arthropods

EEC RQ EEC RQ EEC RQ EEC RQ EEC RQ

2 104.30 52 .15 47.80 23.90 58.67 29.33 6.52 3.26 40.85 20.42
Size class not used for dietary risk quotients

Table A

- 6 . Upper Bound Kenaga, Chronic Mammalian Dose

- Based Risk Quotients

Size

Class (grams) Adjusted

NOAEL EECs and RQs

Short Grass Tall Grass Broadleaf Plants Fruits/Pods/Seeds Arthropods Granivore

EEC RQ EEC RQ EEC RQ EEC RQ EEC RQ EEC RQ

15 0.22 99.44 452.44 45.58 207.4 55.93 254.50 6.21 28.28 38.95 177.2 1.38 6.28

35 0.18 68.73 386.48 31.50 177.1 38.66 217.39 4.30 24.15 26.92 151.3 0.95 5.37

1000 0.08 15.93 207.17 7.30 94.95 8.96 116.53 1.00 12.95 6.24 81.14 0.22 2.88