December 1, 2014

Russell Wasem Document Processing Desk (DCI/PRD) Office of Pesticide Programs U.S. Environmental Protection Agency One Potomac Yard 2777 S. Crystal Drive Arlington, VA 22202 Subject: Federal Register, Vol. 79, No. 146; Wednesday July 30, 2014 (Page 44169) Preliminary Risk Assessments for Dicrotophos EPA-HQ-OPP-2008-0440 Dear Mr. Wasem, AMVAC Chemical Corporation (AMVAC) is submittingthese comments in response to US EPA's recently released Preliminary Risk Assessment for dicrotophos. AMVAC is the data owner and only holder ofatechnical registration in the US. Additionally, AMVAC holds end use registrations and will be defendingthe use ofthe product here in the US. We appreciate the opportunity to provide additional information and comments to the Agency and look forward to discussing the next steps afterthe Agency has had a chance to review all the comments submitted to the docket. Dicrotophos is a critical tool for US cotton growers to control pests that would otherwise destroytheir crop. The National Cotton Council reports that the annual economic activity generated by cotton and its products in the U.S. economy is estimated to be in excess of$120 billion. As pest management issues evolve in cotton, growers need tools that are not only effective but also augment their Integrated Pest Management (I PM) and Integrated Resistance Management (IRM) programs, and provide a positive economic return. Please see attached report (Appendix 1) for a more detailed reporting ofthe benefits ofdicrotophos use in cotton. The Agency's Preliminary Risk Assessment addresses several different exposure scenarios but we have focused on those the Agency identified as potentially concerning- aggregate riskspecifically drinking water and ecological risk. With respect to drinking water and aggregate risk, AMVAC is providing in an attachment specific and general comments concerning the Agency's drinking water and aggregate risk assessments (Appendix 2). Our submission focuses on the dietary consumption ofsurface-based drinking water, which has been shown to drive the aggregate risk assessment. The acute aggregate risk is acceptable at the 95th percentile for all subpopulation groups and information contained in this report indicates that exposure levels are likely lowerthan that calculated by the baseline PRZM/GW modeling reported bythe Agency. The sub-chronic aggregate risk calculated through Calendex is based on a 21 day 4695 MacArthur Court, Suite 1200, Newport Beach, CA, 92660 · Phone (949) 260-1200steady state exposure period. At the 95th percentile, the Agency calculated sub-chronic-based exceedances for certain subpopulation groups. By applying sensitivity analysis to several environmental fate parameters, it can be shown that these exceedances can be reduced significantly to levels that would not be ofconcern through refinement ofthese variables. Although additional modeling efforts may be useful, a substantive database of higher tier monitoring data is already available and can be conservatively applied to more accurately predict the 21 day average surface water exposure levels. Based on this assessment, there would be no sub-chronic exceedances ofany ofthe population subgroups at the 95th percentile. On this basis, dicrotophos use on cotton does not pose an aggregate dietary risk of concern. AMVAC is continuing the analysis provided for in this document and intends to submit a more comprehensive assessment within 90 days ofdelivery ofthis response. With respect to ecological risk, AMVAC is providing in an attachment specific and general comments concerning the Agency's ecological risk assessment (Appendix 3). A review of ecological incident reports does not yield any findings ofeffects from the agricultural use ofthis product in cotton, which strongly suggests the label mitigation measures put in place duringthe RED, have adequately addressed ecological risk. The fact that cotton fields do not provide a good source of nutrition to animals is in itselfsome rationale as to whythis use should not significantly affect wildlife. While there are some studies that have assessed the potential impact of dicrotophos to avian species, AMVAC's review ofthese studies has determined they are flawed in design and therefore do not provide any meaningful data. For this reason, the most accurate assessment of ecological risk must be performed using modeling. An examination ofthe baseline modeling reported by EPA has led to refinements based on free metabolic rate assessments for certain focal species. A refinement ofthe foliar dissipation default value is also justified in this report. From this effort, risk quotients are estimated to be less than 10for all focal species. AMVAC is continuingthe analysis provided for in this document and intends to submit a more comprehensive assessment within 90 days ofdelivery ofthis response. AMVAC has provided a response to EPA's aquatic risk assessment within our ecological risk assessment document. The EPA has determined that the risk to larger aquatic organisms is acceptable; but that there is a low level risk to invertebrates. It is our viewthat a highertier assessment will demonstrate that the risk to these lower level species is also acceptable. AMVAC is continuing the analysis provided for in this document and intends to submit a more comprehensive assessment within 90 days ofdelivery ofthis response. There are some specific issues and corrections AMVAC wishes to address with respect to the Preliminary Risk Assessment:
1. In the July 10, 2014 Transmittal ofthe Preliminary Environmental Fate and Ecological Risk Assessment for the Registration ofdicrotophos (Case# 145), page 38 of 102, the Agency defines the 33-Day Fish Early Life Stage (ELS) Study (MRID 48482901) as "supplemental." Please see attached document (Appendix 4) to clarifythe deficiencies cited in an effort to upgrade this study to "core." 4695 MacArthur Court, Suite 1200, Newport Beach, CA, 92660 · Phone (949) 260-12002. In the July 10, 2014 Transmittal ofthe Preliminary Environmental Fate and Ecological Risk Assessment for the Registration ofdicrotophos (Case# 145), page 38 of 102, the Agency defines the 21-Day Chronic Flow-Through Toxicity Study (Daphnia Magna)(MRID 44956501) as "supplemental." In May 2014, AMVAC submitted the inadvertent missing data from the specified Table 7 and this study should now be considered fully upgraded. 3. In the July 10, 2014 Transmittal ofthe Preliminary Environmental Fate and Ecological Risk Assessment for the Registration ofdicrotophos (Case# 145), page 45 of 102, the Agency defines the Tier I Seedling Emergence Study (MRID 48482902) as "supplemental." AMVAC will be submitting a document to clarify the deficiencies cited in an effort to upgrade this study to "core" within a couple ofweeks.
4. In the July 10, 2014 Memorandum for dicrotophos: Human Health Risk Assessment for Registration Review ofdicrotophos, the Summary ofToxicological Doses and Endpoints and Points of Departure for dicrotophos (page 23 of92), lists the MRID 4615205 for both the Acute Dietary and the Incidental Oral Single Day and it should be listed as MRID 46153205.
5. In the July 10, 2014 dicrotophos: Acute and Steady State Aggregate Dietary (Food and Drinking Water) Exposure and Risk Assessments to Support Registration Review, the Summary ofToxicological Doses and Endpoints for dicrotophos for use in Human Health Risk Assessments (page 6 of 20), the MRID for Acute Dietary is listed as 4615205 and should be listed as MRID 46153205. Next, on page 17 of20 ofthis document, the active ingredient "coumaphos" is listed instead ofdicrotophos on lines 1 and 2. Finally, Section VIII. Results/Discussion paragraphs (page 7) and Section IX. Characterization of Inputs/Outputs (page 17) do not match up with their associated charts. Per Russell Wasem, via email on August 7, 2014, we believe the charts to contain the correct information and the paragraph descriptions to contain incorrect data. Again, AMVAC appreciates the opportunityto provide these comments and additional information to the Agency and looks forward to the chance to discuss the next steps with the Agency. Ifthere are any questions or issues with this response, I can be reached at 949-221- 6146 or via email at KrystaiJ@amvac-chemical.com. Kind regards,

# 1\.~ Krystal Jenkins, Regulatory Product Manager AMVAC Chemical Corporation

20141201.kj.dicrotophos risk assessment.us 4695 MacArthur Court, Suite 1200, Newport Beach, CA, 92660 · Phone (949) 260-1200Volume 1 of5- Submission Transmittal Document Name and Address ofSubmitter: AMVAC Chemical Corporation 4695 MacArthur Court, Suite 1200 Newport Beach, CA 92660 Regulatory Action: Submission of Preliminary Risk Assessment Response for Dicrotophos
Transmittal Date: December 1, 2014 List of Submitted Studies· MRID Number Volume Number 1 of5
2 of5

3 of5

4 of5

5 of5

Company Name:
Company Official:
Company Contact: EPA Study Title
Transmittal Document
AMVAC November 2014 response to EPA's Preliminary Environmental Fate and Ecological Risk Assessment for the Registration of dicrotophos (Case# 145) Response to EPA's Preliminary Drinking Water Exposure and Acute and Steady State Aggregate Dietary Risk Assessments for Dicrotophos Response to EPA's Preliminary Environmental Date and Ecological Risk Assessment for Dicrotophos Response to the Data Evaluation Record on the Fish Early Life Stage Toxicity of Dicrotophos Technical to Fathead Minnow

AMVAC Chemical Corporation

Krys'tal Jenkins, Regulatory Product Manager Krystal Jenkins, Regulatory Product Manager 949-221-6146 KrystaiJ@amvac-chemical.com Guideline Number



### ------------

4695 MacArthur Court, Suite 1200, Newport Beach, CA, 92660 ·Phone {949) 260-1200

# Appendix 1TITLE: AMVAC November 2014 response to EPA's Preliminary Environmental Fate and Ecological Risk Assessment for the Registration of dicrotophos (Case #145)

Author: AMVAC Chemical Corporation

Sponsor: AMVAC Chemical Corporation 4695 MacArthur Court, Suite 1200 Newport Beach, CA 92026

Date: November 24, 2014

Page 1 of6NO CLAIM OF CONFIDENTIALITY

No claim ofconfidentiality, on any basis whatsoever, is made for any information contained in this document. I acknowledge that information not designated as within the scope of FIFRA sec. lO(d)(l)(A),(BL or (C) on which pertains to a registered or previously registered pesticide is not entitled to confidential treatment and may be released to the public, subject to the provisions regarding disclosure to multinational entities under FIFRA lO(g).

Submitter: Date:

Typed name ofsigner: Jon C. Wood Director of Registrations

Typed name ofcompany: AMVAC Chemical Corporation

Page 2 of6STATEMENT OF GLP COMPLIANCE This technical document provides information that assesses the benefits of use ofdicrotophos. The document does not contain any new or original data. Therefore, the requirements of40 CFR Part 160 are not appropriate to this document.

Author: Date:

I •

Typed name ofsigner: Krystal Jenkins Regulatory Product Manager

Typed name ofcompany: AMVAC Chemical Corporation

Submitter/Sponsor: Date:

## ()1-k-~1'/ I
Typed name ofsigner: Jon C. Wood Director of Registrations

Typed name ofcompany: AMVAC Chemical Corporation

Page 3 ofGAMVAC November 2014 response to EPA's Preliminary Environmental Fate and Ecological Risk Assessment for the Registration of dicrotophos (Case #145)

AMVAC Chemical Corporation (AMVAC) is submitting this updated benefits analysis as part ofour response to EPA's Preliminary Environmental Fate and Ecological Risk Assessment for the Registration of dicrotophos. These comments are the result ofextensive discussions that we conducted with the National Cotton Council, University Extension Service personnel, cotton growers and otherfield experts and experienced users ofdicrotophos. Dicrotophos is a critical product used by cotton growers across the United States to protecttheir crop from pests that would otherwise destroy the crop and/or significantly reduce yield. The National Cotton Council reports that the annual economic activity generated by cotton and its products in the U.S. economy is estimated to be in excess of$120 billion. As pest management issues evolve in cotton, growers need tools that are not only effective but also augment their Integrated Pest Management (IPM) and Integrated Resistance Management (IRM) programs, and provide a positive economic return. Dicrotophos remains an economical product to growers in times of high production costs and low cotton prices. Dicrotophos is a needed option for early season use to provide a foliar alternative to acephate for thrips control. Seed treated neonicotinoid insecticides have become afairly standard treatment for growers. This is resulting in confirmed resistance ofthrips to thiamethoxam in the mid-south states. This increases the need forfoliar applied thrips control following seed treated insecticides. Acephate is not a preferred option because it has atendency to flare spider mites while dicrotophos provides suppression ofthis pest. Options for early season control ofspider mites are limited. In mid-to-late season cotton, the flexibility to manage plant bug and stink bug infestations afterfirst bloom is critical since nationally these are two ofthe most damaging pests to cotton and ones with which dicrotophos has an excellent performance record. In addition to yield reduction, stink bugs cause further economic loss due to reduced lint quality so maintaining the use of Dictrophos is critical. Pest Pressure and Control For plant bug management programs, it is not uncommon to make eight to ten insecticide applications in a growing season. Other key active ingredients used are thiamethoxam, imidacloprid, acephate, oxamyl, sulfoxaflor and pyrethroids. Rotation ofchemistry is critical to IRM. Dicrotophos has an excellent fit afterfirst bloom stage ofgrowth and works well in the rotation plan after neonicotinoid insecticides are used. It also has an excellent fit late in the season when a mixed population of plant bugs and stink bugs are in the field. For stink bug control, it is not uncommon in the Southeastern states to make fourto six total insecticide applications due to stink bug migration into cotton from corn, soybeans, peanuts and other crops as they reach maturity. Common insecticides used to manage stink bugs are dicrotophos, acephate, pyrethroids and to a limited degree neonicotinoids. Ofthe three main species ofstink bugs (green,

Page 4 of6southern green and brown}, there is variability in their response to different insecticides. Dicrotophos performs very well on all species, but is particularly effective on brown stink bugs compared to other insecticides, such as pyrethroids and acephate. The loss of methyl parathion for use on cotton in 2012, reduced the options available. Because ofthe limited insecticide choices available, dicrotophos is avital tool to manage resistance to pyrethroids. Application Parameters Although, used sparingly overall, dicrotophos is used strategically and is of immense importance to cotton growers. The number oftotal insecticide applications needed for plant and stink bug control is fluid and will depend on the circumstance ofthe year and the location ofthe crop. The current label for dicrotophos allows for use in cotton based on the cotton stage ofgrowth. Early season use (emergence to pre bloom) allows for one application for eitherthrips orflea hoppers. Late season use (first bloom to 30 days prior to harvest) allows for atotal application of no more than 16 fluid oz/acre. Early season use is applied at lower rates to effectively control thrips or cotton flea hoppers. In some southern states, tobacco thrips have been reported to be resistant to neonicotinoid seed treatments; and with this threatto cotton producers, dicrotophos is a key tool for managing early season thrips. In terms ofthe economics ofthis early season control, dicrotophos cost is around $4.50/acre compared to acetamiprid at $12.00/acre. Use ofdicrotophos does not trigger outbreaks ofsecondary pests, whereas acephate, which is also utilized to manage some insect pests, can trigger spider mites and cotton aphids particularly. For late season use, dicrotophos is essential. It is the only pesticide that can control plant bugs and stink bugs in a mannerthat prevents significant damage to cotton crops, because applications ofdicrotophos can be made during the critical blooming and boll set period when cotton bolls must be protected. Inability to make sufficient applications will reduce effectiveness ofthe grower's pest management program, resulting in reduced yield and cotton fiber quality. Because dicrotophos is more efficacious than other chemistries against specific pests at specific times, it is a key component for successful implementation of IRM and IPM strategies. Aerial Application and Buffers Maintaining aerial application is critical for the effective use ofdicrotophos to manage both early season and late season pests. It is not uncommon for wet field conditions to prevent ground application for thrips control, particularly in the Mid-South and Southeastern states. Thrips can cause significant damage to young cotton plants in avery short time, therefore growers rely heavily on aerial applications when weather prevents ground application. In late season plant bug and stink bug applications, aerial application is preferred to avoid crop damage from ground equipment. Wet weather can also be a factor in preventing timely applications in the mid to late season as well. Leaving an untreated area around afield is not a proven or acceptable IPM practice. Stink bug and other pest populations are most often heavier on the border when the pests are migrating into fields from other host crops nearby such as corn or peanuts. Buffers would serve as a nursery to create a rapid

Page 5 ofGsource for pest reinfestation into the remainder ofthe field as well as neighboring fields. In addition to the excessive damage to cotton plants in the border areas, the remainder ofthe field would incur more severe pest pressure and elevated yield losses. Such an approach could escalate the need for more frequent insecticide sprays to manage plant bugs and stink bugs. Retreatment Interval The current restriction on dicrotophos for late season application is afourteen day retreatment interval which allows growers some flexibility while still limiting environmental impact. Any further restriction added to this would have serious consequences as itwould cause an increase in the use ofother products that may be more environmentally harmful, especially for pollinators. Brown stink bugs are known to be highly mobile and can re-infest afield in as little as two weeks. Industry Comments The National Cotton Council ofAmerica [sent via email on October 23, 2014 to Khue KguyenL the Arizona Pest Management Center [sent via email on November 10, 2014 to Khue Kguyen] and the North Carolina Department ofAgriculture and Consumer Services [submitted to the public docket EPA-HQOPP-2008-0440-0028] all submitted extensive comments describing the critical need for dicrotophos with respect to their particular issues, pest pressures, buffers, and reentry intervals. AMVAC has carefully reviewed these letters and fully supports the comments.

Page 6 ofG

# Appendix 2

### STUDY TITLE Response to EPA's Preliminary DrinkingWaterExposure and Acute and Steady State Aggregate Dietary RiskAssessments for Dicrotophos

TEST GUIDELINE: None



### AUTHOR: DickFreedlander, Ph.D. 1



### REPORT COMPLETIONDATE: November 24,2014



### TECHNICAL SUPPORT: Timothy L. Negley Christopher Hassinger ARCADIS U.S. Inc. 6723 Towpath Road Syracuse, NY 13214



### PROJECT NUMBER: AMVAC Report#800-REV-020



### SUBMITTED BY: 1AMVAC Chemical Corporation 4695 MacArthur Court, Suite 1200 Newport Beach, CA 92660



### TOTAL PAGES: 34 

### NO CLAIM OF CONFIDENTIALITY

Page 1 of34No claim ofconfidentiality, on any basis whatsoever, is made for any information contained in this document. I acknowledge that information not designated as within the scope ofFIFRA sec. 10(d)(l)(A), (B), or (C) and which pertains to a registered or previously registered pesticide is not entitled to confidential treatment and maybe released to the public, subject to the provisions regarding disclosure to multinational entities under FIFRA lO(g).

Company: AMV AC Chemical Corporation

CompanyAgent: Dick Freedlander, Ph.D. Director ofEnvironmental Sciences AMVAC Chemical Corporation

Signature:

# ----'~'--------='-------~__:,,.____ ==-------- 

### -==:::::::::: Date:

__ 

### .:__fl_.!.(_z._L/..:........jf"--Z=--D_I L}....l......--

____ _

Page 2 of34GOOD LABORATORYPRACTICE COMPLIANCE This study does not fall under EPA FIFRA Good Laboratory Practice (GLP) Standards set forth in Title 40, Part 160 ofthe Code ofFederal Regulations.

Submitter:

Signature: Date: DickFreedlander, Ph.D. Director of Environmental Sciences AMVAC Chemical Corporation

Page 3 of34TABLE OF CONTENTS

1.0 SUMMARY

......................................................................................................................................6 2.0 INTRODUCTION

............................................................................................................................ 8 3.0 GENERAL COMMENTS

................................................................................................................ 8 3.1 Use Patterns

.................................................................................................................................. 8 3.2 Aggregate Exposure Considerations

............................................................................................. 8 3.3 EPA's Assessment ofDrinking Water Exposure Based on Modeling

..........................................9 3.3.1 GroundwaterModeling

.........................................................................................................9 3.3.2 Surface Water Modeling

.......................................................................................................9 3.4 Water Modeling Refinements

..................................................................................................... 10 3.4.1 Percent Crop Treated

.......................................................................................................... 10 3.4.2 Soil Adsorption

................................................................................................................... 11 3.4.3 Aerobic Aquatic Metabolism

.............................................................................................. 13 3.4.4 BufferZones

....................................................................................................................... 15 3.5 Surface Water Monitoring Data

.................................................................................................. 15 3.5.1 Dicrotophos Use from 1992 to 2009

................................................................................... 16 3.5.2 NAWQA Sampling Sites for Dicrotophos

.......................................................................... 17 3.5.3 NAWQA Sampling Sites with Dicrotophos Detections

..................................................... 18 3.5.4 Location ofHighest Measured Dicrotophos Concentration in NAWQA Data Set

.............20 3.5.5 Discharge Rates vs. Residue Detections at Site ofHighestDicrotophos Concentration

....21 3.5.6 Relative Contributions ofDrift and Runofffor Dicrotophos Surface Water Concentrations 22 3.5.7 Refinement ofSurface WaterExposure and Resulting Aggregate Exposure Risk

.............23 4.0 SPECIFIC COMMENTS

................................................................................................................27 4.1.1 EPA memorandum ofJuly 10,2014: (PC Code: 035201; DP Barcode 393772); "Dicrotophos: DrinkingWater Assessment for Reregistration Review", byAndrew Shelby (Physical Scientist) Environmental Risk Branch 6

.............................................................................................27 4.1.2 EPA memorandum ofJuly 10,2014: (PC Code: 035201; DP BarcodeD418103); "Dicrotophos: Acute and Steady State Aggregate Dietary (Food and Drinking water) Exposure and RiskAssessments to Support Registration Review", by ThurstonMorton (Chemist) RiskAssessment Branch IV, Health Effects Division (7509P)

......................................................................................31 5.0 REFERENCES USED IN THE ASSESSMENTS

.........................................................................34

Page 4 of34ListofTables and Figures



### Table 3-1 Calculation ofSurface WaterParent Compound EDWCs Table 3-2 Calculation ofSurface Water Total Toxic Residues EDWCs Table 3-3 Sensitivity ofParent Compound EDWCs to Soil Adsorption Table 3-4 Sensitivity ofTotal Toxic Residues EDWCs to Soil Adsorption Table 3-5 Sensitivity ofParent CompoundEDWCs to Aquatic Metabolism Table 3-6 Sensitivity ofTotal Toxic Residues EDWCs to Aquatic Metabolism Table 3-7 Sensitivity ofParent Compound EDWCs to SprayDrift Table 3-8 Sensitivity ofParent Compound EDWCs to Spray Drift Table 3-9 Dicrotophos Steady State Dietary Exposure forMS at Cotton MaximumRate Table 3-10 Dicrotophos Steady State DietaryExposure forMS at Cotton Typical Rate Table 3-11 Dicrotophos Steady State DietaryExposure for NC at Cotton Maximum Rate Table 3-12 Dicrotophos Steady State DietaryExposure forMS at Cotton Typical Rate Table 3-13 Dicrotophos Steady State DietaryExposure for TX at Cotton Maximum Rate Table 3-14 Dicrotophos Steady State DietaryExposure for TX at Cotton Typical Rate Figure 3-1 Map ofDicrotophos Use from 1992 to 2009 Figure 3-2 NAWQA Map ofSamplingLocations for Dicrotophos Analysis ofSurface Water Sites Figure 3-3 NAWQA Map ofSampling Locations for Detections ofDicrotophos at Surface Water Sites Figure 3-4 Distribution ofNAWQA Surface Water Concentrations for Dicrotophos Figure 3-5 Map Location ofHighestMeasured Concentration ofDicrotophos withinNAWQA Surface Water Sampling Sites Figure 3-6 Discharge Rate vs. Dicrotophos Residue Concentration at the NA WQA Site of HighestResidue Concentration

Page 5 of341.0 SUMMARY The onlyregistered us for dicrotophos is on cotton, which when processed to a food commodity contributes very little to the overall dietary burden. Therefore, drinking water is the dominant factor in the dicrotophos aggregate risk assessment. The EPAhas recently determined that the use ofgroundwater as a drinking water source would not yield any exceedances in the aggregate risk assessment. For thatreason, this response is primarily focused on surface water exposure. The EPA has assessed dicrotophos surface water exposure in relation to the compound's acute population adjusted dose (aPAD). The Agency has demonstrated that the aPAD is not exceeded at the 95th percentile for any ofthe modeled cotton scenarios. This percentile wouldbe appropriate for use within the aggregate risk assessment. Even when considering exposure within a sensitivitybased analysis, at higherpercentiles only one ofthe sub-population groups (all infants, <1 year old) yielded an exposure that was greaterthan 100% ofthe aPAD andthis exposure was associated withthe maximum, notthe typical application rate. On this basis and in recognition ofthe conservative nature ofthe Agency's baseline analysis, the acute aggregate risk for dicrotophos should be deemed acceptable. EPAhas also conducted a baseline modeling assessmentusing Calendex for developing a conservative estimate ofsub-chronic risk. This assessment utilized PRZMIEXAMS modeling for determination ofthe average weekly surface water exposure. The Agencythen based its 21- day exposure using a 3-weekrolling average over a year. From this analysis, EPA identified exceedances for some population groups atthe 95th percentile. The highest exceedance is associated with infants (all infants, <1 year old) and the maximum use rate associated with the Mississippi use scenario. That exceedance EPA assumes is approximatelytwice (i.e., 2.1X) the acceptable cPAD level. Somerefinements have been identified in this reportthat couldbe pursued within the modeling, (e.g., conducting additional soil metabolism studies to eliminate the use ofcorrection factors). Further, this document focuses on two effective means for aggregate risk refinement that can be immediately implemented. The first beingthe refinement ofthe modeling based on the provisions ofthe current dicrotophos label (e.g., established buffer zone requirements) and the second being the utilization ofhigher tier surface water exposure databyfurther consideration of available surface water monitoring data. Onthe first point, information contained withinthis report indicates that modeled surface water contamination would primarily occur through runoffevents, although a component ofthe residue wouldbe associated with drift potential. It is recognized that currently there is not an accepted modeling approach for translating buffer zones to surface water exposure levels. Nor is there a validated approach for refining drift contributions based on drift reduction technology practices already in place. Still, it is quite evidentthatthese factors do translate to a significant lowering ofsurface water exposure from chemical application.

Page 6 of34Concerningthe secondpoint, the USGS National Water-Quality AssessmentProgram (NAWQA) andthe USDA's Pesticide DataProgramprovide approximately 8,500 samplings of agriculturally relevant surface waterbodies. This data provides a realistic and more accurate assessment ofsurface water exposurepotential to dicrotophos use. Although the Calendex-based risk assessmentutilizes a weekly average concentration, it would be more appropriate to adopt a 3-week average concentration in order to match the response time associated with the toxicological endpoint. In either case, it is importantto recognize that uncertainties associated withthe determination ofthe peakwater concentrations within the monitoring data become much less influential when considering a sub-chronic based exposure. Further, the use ofa very extensive monitoring database provides an opportunityto examine exposure trends and better understand temporal exposure trends. Therefore, bytaking advantage ofthis monitoring database, it is possible to more accurately assess surface water exposure in a meaningful and more realistic manner. WithinUSDA's Pesticide DataProgram, there were a limited number ofsamplings for dicrotophos with only 4 detections from 232 finished water samples and 3 detections from 253 untreated water samples. These limited detections would suggest there are few incidents of dicrotophos getting into water samples. The highestreported concentration was 0.003 ppb, which is more than 2 orders ofmagnitude belowEPA's PRZMIEXAMS modeled concentration. Within NA WQA, it is immediately evident that dicrotophos exposure is low. EPAhas reported thatwithin the entire collection ofsampling sites, there are only 57 detections (<1% ofthe sampling) withmeasureable residues. With one exception, all residues are at concentration levels that are less than 0.3 ppb, a level that is 2.7X lowerthan whatwas predicted for subchronic exposure in baseline modeling conducted bythe Agencyusing PRZMIEXAMS. The implications ofthis single >0.3 ppb concentration (i.e., 6.83 ppb) sampling in Washington County, Mississippi, was further examined to better understand the implications ofthis result. It was noted that samplingtaken on the next day had measured residues that were more than an order ofmagnitude lower. As the Agency has determined that the steady state exposure is associated with a 21 day period, it is clear that the average surface water concentration at this site wouldbe much lowerthanthe peak concentration. Further, the absence ofa relationship between discharge rate and residue concentrations atthis site, challenges the integrity ofthis aberrant datapoint. Within this report, a very conservative approach was used for refining the 21 day exposure of dicrotophos in surface water using the extensive monitoring database. A concentration of0.3 ppb from the modeling data, whichrepresents an upper limit or near upper limit (i.e., >99.9 percentile) in monitoring data expoaure was used to refine the aggregate risk assessment. Under these circumstances, there are no exceedances atthe 95th percentile in the aggregate risk assessment at the maximum use rate. Therefore, this still conservative assessment demonstrates thatthe use ofdicrotophos on cotton does notexceedthe health-based safety standards ofthe EPA. Further, this assesment does not consider label mitigation factors already in place on the current labels thatwouldhave a significantbearing on lowering exposure levels even further.
Page 7 of34

### 2.0 INTRODUCTION The Environmental Protection Agency (EPA) released their Preliminary Environmental Fate and Ecological Risk Assessment (ERA) for the Registration ofDicrotophos in July, 2014. This report outlines the preliminary aggregate risk assessment conducted byEPAunderthe Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA) for registration review ofdicrotophos. Dicrotophos is a systemic broad spectrum organophosphate insecticide with a mode ofaction that interferes with the acetylcholinesterase enzyme (AChE). AMVAC Chemical Corporation (AMVAC) currentlymanufactures two end-use products that contain dicrotophos; Bidrin® 8 (82% dicrotophos) and BidrinXP IITM (50.7% dicrotophos 

### + 11.2% bifenthrin). Bidrin 8 and BidrinXP II are onlyproposed for use on cotton through both aerial and ground application. As part ofthe registration reviewprocess, AMV AC has retained ARCADIS to review EPA's surface water exposure assessment. The following report has two main sections. Section 3.0 provides general comments on the approaches used by the Agency in developing their exposure, effects, and risk characterization. Section 4.0 contains specific comments on the Agency's report that includes typographic errors, data or calculation errors, and other specific comments.



### 3.0 GENERAL COMMENTS The following general comments address key issues that have been identified within EPA's preliminarydrinking water exposure and acute and steady state aggregate dietary risk assessments for dicrotophos.

3.1 Use Patterns There have been significant changes to the use patterns for dicrotophos since it was first registered in the United States. These changes and important mitigation measures adopted on its labels have resulted in significant decreases in human population and environmental exposure.



### 3.2 Aggregate Exposure Considerations There have been significant changes to the usepatterns for dicrotophos since it was first registered in the United States. The onlyremaining food use is associated with cotton and the only potential exposure through ingestion ofdicrotophos residues in cottonseed oil. As there are no residential uses, exposure is driven by ingestion ofdrinking water. Therefore, aggregate exposureto dicrotophos is approximately equal to the exposure associated with drinking water.

Page 8 of343.3 EPA's Assessment ofDrinking WaterExposureBased on Modeling 

### 3.3.1 GroundwaterModeling EPA's assessment ofgroundwater exposure utilizes both maximum and typical use rates associated with dicrotophos use on cotton. The Agency has used a total toxic residues (TTR) approach in its assessment. However, AMV AC is proposing thatthis grouping be redefined to only consider residues thatwould be expectedto have cholinesterase inhibiting potential. Additional information is providedunder the "Specific Comments" section ofthis report. The Agency also noted that it has adopted its conservative approach ofapplying a 6X factor to the aerobic aquatic metabolism input parameter due to data deficiencies, rather than due to any determination ofcurrent data. Although from apolicyperspective this is appropriate, it is also recognized thatthis parameter likely exaggerates the degradation rate ofdicrotophos under aerobic aquatic conditions. The PRZM/GW modeling employed byEPA yielded a groundwater concentration of0.06 ppb, which was employed for both acute and chronic risk considerations. This concentration is more than 2 orders ofmagnitude lower than the acute concentration calculatedby EPA for surface water acute exposure. The concentration in groundwater for chronic exposure is more than 1 order ofmagnitude lower than the concentration calculatedbyEPA for surface water chronic exposure. The groundwater aPAD is not exceeded at the 95th percentile for any ofEPA's modeled cotton scenarios. Athigherpercentiles only one ofthe sub-population groups (all infants, <1 year old) yielded an exposure that was greaterthan 100% ofthe aPAD andthis exposure was associated with the maximum application rate. The groundwater cPAD is not exceeded for any EPA's modeled cotton scenarios, even at higher percentiles. On this basis, it canbe concludedthat drinking water associated with groundwaterwould not pose an aggregate risk concern.



### 3.3.2 Surface WaterModeling EPA's assessment ofsurface water exposure also utilizes both maximum and typical use rates associated with dicrotophos use on cotton. Again, the Agency has used a total toxic residues (TTR) approach in its assessment. The Agency also adopted its conservative approach of applying a 6X factor to the aerobic aquatic metabolism inputparameter. The PRZMIEXAMS modeling employed byEPA yielded a concentration of 12.44 ppb for acute risk considerations and 0.8 ppb for chronic risk considerations. Based on preliminarybaseline modeling, dicrotophos exposure through surface-based drinking water would exceed sub-chronic regulatory limits placed on aggregate risk.

Page 9 of343.4 Water Modeling Refinements 

### 3.4.1 Percent Crop Treated EPAprovided surface waterEDWCs modeled in PES that accounted for the percent crop treated in all cases except for the California scenario. The product is not currently labeled for use in this state. Forthis reason, AMY AC proposes that EPA remove this scenario from its assessment. However, as the Agency is currently evaluating a CAuse, we believe thatthe same factors should be applied to all scenarios. ARCADIS has performed calculations in a comparable mannerto EPA for all ofthe scenarios; but has also applied the percent crop treated factor to the California scenario. Table 3-1 Calculation ofSurface Water Parent Compound EDWCs

0.1 10.84 0.57 0.32

0.1 10.84 0.58 0.32

0.1 9.33 0.62 0.32
Parent 0.1 9.33 0.62 0.32 Compound

Residues 0.1 12.01 0.56 0.30
0.1 12.01 0.56 0.30 CA Cotton Maximum 0.1 6.90 0.55 0.51 (USEPA)<

.CA Cotton Maximum 0.1 (ARCADIS)
1/ Modeling performed in PES utilizing a percent crop treatment factor of33% 2/ Shaded values**indicate~** 10% change in EDWCs between EPA and ARCADIS

Page 10 of34Table3-2 Calculation ofSurfaceWaterTotal Toxic Residues EDWCs



### ... Surface Water EDWCs .· ·....
_.... Crop Scenario Prob. 1 Peak I 30-Yr

...· Yearly Avg

. .

. .

•••••• MS Cotton Maximum 0.1 11.03 0.72 0.41


### .. (USEPA)

••••• ···.· 

## . ·•.
•••••• MS Cotton Maximum

••••• (ARCADIS) 0.1 11.03 0.72 0.41

·. NC Cotton Maximum 0.1 9.60 0.80 0.41 (USEPA)

.. Total 

### NtCotton Maximum 0.1 9.60 0.80 0.41 Toxic (}\RCADIS) Residues TXGotton Maximum 0.1 12.44 0.70 0.38 {USEPA) TXCotton Maximum 0.1 12.44 0.70 0.38 (ARCADIS) ·_:. CACotton Maximum 0.1 7.51 0.70 0.65 (lJSEPA) ..

.·

. . .

# .·i!t~j: -- . 

### ·- .

# ~·-K~-~i~~;:,\,:. GA Cotton Maximum··•·· 0.1 0.23.··- (ARCADIS) .·.··· \;'."?:"""""
1/ Modeling performed in PES utilizing a percent crop treatment factor of 33% 2/ Shaded values**indicate~** 10% change in EDWCs between EPA and ARCADIS



### 3.4.2 SoilAdsorption The potential effect on surface water exposure byrefining the soil adsorption parameterwas considered. There are two avenues for such refinement. First, as there does not appearto be a correlationbetweenpercentorganic matter and compound adsorption, individually assessing the prevalent soils used for cotton in the use regions would provide for a more refined exposure assessment. Because the range ofsoil properties is diverse, there are unanswered questions concerning implementing an effort in this area. Because there are bettermeans for reining exposure, there are no plans for initiating studies in this area. Second, there is the possibilityofrefining exposure onthe basis ofdetermining the fraction of bioavailable residue inthe waterphase and correcting the Kd value onthat basis. There are techniques that have been developed for this type ofdetermination such as solid phase microextraction (SPME). Because dicrotophos has some soil bindingpotential, there is an expectation that exposure to bioavailable residue would be lower than wouldbe indicated bythe current Kd value.

Page 11 of34A sensitivity analysis indicates that a 3X increase in the Kd would lower acute exposure by more than 10% in the three major cotton modeling scenarios for TX, MS, and NC. Changes ofthis magnitude would normally be considered small butbecause the risk exceedances within the steady state risk assessment are not so significant, these differences could be meaningful. Atthis time, AMVAC believes that surface water exposure refinement canbe better addressed by other means described in this report; thus this work is not being initiated at this time. The sensitivity analyses as performed byARCADIS for parent compound and total toxic residues (TTR) residues is providedbelow.

Table 3-3 Sensitivity ofParent Compound EDWCs to Soil Adsorption

:, Sensitivity ofParent Compound EDWCs to Increasing ...... SoiJ Adsorptioll Coefficient (Kd)11 

### swcc Sensitivity 1-in-10Year Values (ppb)31 % Reduction31 ·Crop Analysis21 Peak Yearly 30-Yr Peak Yearly 30-Yr Scenario Scenario**Avg~** i·. Avg. Baseline 10.80 0.65 0.35 MS .,. Kdx3 8.65 0.62 0.19 .:.20.1 -4.1 -9.1 Cotton Kdx10 5.71 0.51 0.26 

### . ,41-2 -21.8 -25.6 Baseline 10.00 0.84 0.39 :

NC Kdx3 8.22 0.67 0.34 

# a:" C:.19;9 -12.9 .·· Cotton 

## -42.:3 KdxlO 5.61 0.49 0.27 -30.4 Baseline 13.10 0.96 0.38 TX Kdx3 11.40 0.73 0.35 

### ;,fJ

# • -3.6 -8.0 Cotton


## .::·,;

### ~:~~0~1,\·•·**f;jr~~,ij.s** c.' KdxlO 7.82 0.53 0.28**·q~** 1/ Modeling performed with Surface Water Concentration Calculator (SWCC) utilizing a percent crop treatment factor of33% 2/ Baseline Kd = 1.24 ml/g (3X = 3.72 ml/g; lOX= 12.4 ml/g) 3/ Shaded values indicate<: 10% reduction in EDWCs relative to baseline scenario

Page 12 of34Table 3-4 Sensitivity ofTotal Toxic Residues EDWCs to Soil Adsorption Sensitivity ofTotalToxicResidue (TTR) EDWCsto Increasing

· •. ··• Soil Adsorption Coefficient (Kd)11 •···· SWCC •·. Sensitivity 1-in-10 Year Values (ppb)31 ·····% Reduction31 ···• Crop.··.·. Analysis21**r-----.-~--"-'---,...•.---+-~~""""T"-**.. ·**.-.~.~** .. ->....-'--.--.--1 Scenario Scenario
··•·· Baseline



### TX Cotton KdX: 10 Baseline

Kdx 3 ·•· KdxlO Baseline

Kdx3 ··•

. . . . Kdx.lO··· Peak Yearly 30-Yr Peak • Yeai:ly .· ·•**30**

### ~vr

.. Avg. · ...· · ...· .. Avg.

6.01 0.69 11.00 1.09 9.11 0.90 6.24 0.71 13.66 0.97 0.49 12.10 0.96 0.46
. -11.1. -1.3 -6.4 8.38 0.74 0.38 ; -38.6
1/ Modeling performed with Surface Water Concentration Calculator (SWCC) utilizing a percent crop treatment factor of33% 2/ Baseline Kd = 1.24 ml/g {3X = 3.72 ml/g; lOX= 12.4 ml/g) 3/ Shaded values indicate;::: 10% reduction in EDWCs relative to baseline scenario



### 3.4.3 AerobicAquaticMetabolism As a half-life has notbeen defined for dicrotophos degradation by aerobic aquatic metabolism, the EPA has usedthe values for the aerobic soil metabolism and applied a correction factor of 2X. Additionally, because there was limited aerobic soil metabolism data, a correction factor of 3Xwas applied for that value. In total, a 6X correction factor was applied. Therefore, EPA utilized highly conservative half-life values of 16.2 and 17.4 days for parentand total toxic residues as modeling input values for the aerobic aquatic metabolism ofdicrotophos. As shown in the table below, the elimination ofthe 6X correction factor for the aerobic aquatic metabolism value has a modest effect on acute EDWCs, but a fairly significant effect onthe chronic EDWCs. Although the reported concentrations do not include 21-day average values, the annual values attest to the sensitivity ofthe parameter. Atthis time, AMV AC believes that surface water exposure refinement canbe better addressed by other means described in this report; thus this work is not being initiated atthis time. The sensitivity analyses as performed byARCADIS for parent compound and total toxic residues (TTR) residues is provided below.

Page 13 of34Table 3-5 Sensitivity ofParent Compound EDWCs to AquaticMetabolism Sensitivity ofParent Compound EDWCs to Eliminationof6X Correction Factor for Estima1:ingAerobic Aquatic Metabolism Half-life11 ·•... SWCC Sensitivity**1-in~lOYear** Values (ppb)31 ••.•.•.• · ..•·.• % Reduction31 · ...·

...·

•.. Crop Analysis21

. . .·. 30-Yr .··•.·.. k 30-Yr Scenario Scenario Peak Yearly Pea Yearly ·· .· .. Avg. ..·....·· ....· Avg. MS Baseline 10.80 0.65 0.35 Cotton Baseline/2 8.02 0.26

NC Baseline 10.00 0.84 0.39

..·Cotton Baseline/2 7.06 0.27 TX Baseline 13.10 0.76 0.38 Cotton Baseline/2 8.42 0.26
1/ Modeling performed with Surface Water Concentration Calculator (SWCC) utilizing a percent crop treatment factor of33% 2/ Baseline t 112 = 16.2 d (X/2 

### * X/3 = 2.7 d) 3/ Shaded values indicate:?: 10% reduction in EDWCs relative to baseline scenario

Table 3-6 Sensitivity ofTotalToxicResidues EDWCs to AquaticMetabolism Sensitivity ofTotalToxic Residue (TTR) EDWCs to Elimination ofGX Correction FactorforEstimating Aerobic Aquatic Metab()lism Half-life11 SWCC Sensitivity 1-in:..1o YearValues (ppb)31 Crop 30-Yr Yearly Analysis21 30-Yr Yearly Scenario Scenario ·Peak Avg. MS Baseline 11.00 0.81 0.43 Cotton 2.7 d t:l/2 9.14 0.20 0.10

NC Baseline 11.00 1.09 0.50 Cotton 2.7 d tl/2 8.25 0.22 0.10

TX Baseline 13.70 0.97 0.49 Cotton 2.7 d t:l/2 10.80 0.19 0.10
1/ Modeling performed with Surface Water Concentration Calculator (SWCC) utilizing a percent crop treatment factor of 33% 2/ Baseline t1 1 2 = 17.4 d (X/2 

### * X/3 = 2.9 d) 3/ Shaded values indicate:?: 10% reduction in EDWCs relative to baseline scenario

Page 14 of34

### 3.4.4 BufferZones The current labels for dicrotophos prohibits productuse within 25 feet by ground and 150 feet by airto lakes, reservoirs, rivers, permanent streams, marshes, natural ponds, estuaries, and commercial fish ponds. Suchrestrictions would have a significant effect on chemical loading into surface water bodies bybothrunoffand drift. Although there is not an EPAprescribed procedure on assessing the effectiveness ofbuffer zones, there are models available for estimatingthe effectiveness ofdifferent size buffer zones. Recent approaches by different researchers have incorporated the Vegetative Filter Strip model (VFSmod) into EPA's PRZMIEXAMS model. Runoffand erosion predicatedby PRZM is reduced viathe VFSmod prior loading into EXAMS. Calculations can be performed repeatedly on a storm event basis. For relatively rapidly degradingpesticides such as dicrotophos, this approach has been shown to primarily reduce the longer-term EECs, which for dicrotophos yields the exceedances. The acute exposure is less impacted because large rainfall-based runoffevents are not efficiently managedbyvegetative filter strips.



### 3.5 Surface Water Monitoring Data In a drinkingwater exposure assessmentprocess, conducting baseline modeling using conservativeparameters is an appropriate initial step. For dicrotophos, this directs further efforts towards refining the assessment ofsurface water exposure. As in most environmental assessments, developing actual field dataprovides a strong basis for refining exposure assessments based onmodeling and in some cases can improve the reliability ofthe models. In the case ofdicrotophos, the USGS National Water-QualityAssessmentProgram (NAWQA) and the USDA's Pesticide DataProgramprovide approximately 8,500 samplings of agriculturallyrelevant surface waterbodies that have been analyzed for dicrotophos. This information provides an indication ofacute exposure, butmore critical to the regulatory needs for dicrotophos, it provides reliable data that can accurately assess chronic-based exposures in a real world setting. The overlap between the areas associated with dicrotophos use (primarily cotton) and the monitoring data demonstrates that some ofthe data appropriately targets surface waterbodies where the product was used while some ofthe data is in regions where product use is nonexistent orlow. However, even when the data set is paired down to onlyreflectproductuse areas, there remains a substantial monitoring dataset.

Page 15 of34

### 3.5.1 Dicrotophos Usefrom 1992 to 2009
Figure 3-1 Map ofDicrotophos Use from 1992 to 2009

LEGEI'D [=:J stale Bo

...dary Dicrotophos O>unty Boundary To1aI Kilograms 0_1 -3 '4-131 132-1035**~~-** 1036- 4890

- 4891 -159254 N:llES: 1_ DatarepresentUSGS E-PEST tJ[gh) eslirm1es at a the cotnf:y leveL

Page 16 of34 Kilometers o 250 roo 

# -- NJ.VAC CHEMICAL CORP_ NEWPORTBEACH, CALIFORNIA DRINKINGWATER ASSESSMENT DICROTOPHOS ESllMATED USE (1992-2009) 

# ARCADIS AGURE 

### 1

### 3.5.2 NAWQA SamplingSites forDicrotophos
Figure 3-2 NA WQAMap ofDicrotophos SurfaceWater Sampling Locations

LEGEND Dicrotophos Dicrotophos Observed TotaI Kilograms Slate Boundary 0_1 -3 O:mnty Boundary 4 - 131 132-1035 1036-4890 -4891-159254 NOlES: 1_ Data represent USGS E-PEST (High) e9.irmf.es at 3the county lellel from 1992 to 2009_ 2. NAWQAsurfacewater data**avai~lefrom** ;D05to 2010. Kflometers 0 250 500



### ._ • I AMVAC CHEMICAL CORP. NEWPORT BEACH, CALIFORNIA DRINKtiGWATERASSESSMENT DICROTOPHOS OBSERVATIONS VERSUS ESllMATED USE
FIGURE



### X 

# @ARCADIS

The reported detections ofdicrotophos correlate reasonably well with areas ofhigh productuse such as north-east Texas, MS, and GA.

Page 17 of343.5.3 

### NAWQA SamplingSites with DicrotophosDetections
Figure3-3 NA WQAMap ofSamplingLocations for Detections ofDicrotophos at Surface Water Sites

lEGEND Dicrotaphos Dicrotophos

) Observed To1aI Kilogr.tms state Boundary 0_1
- 3 Omnty Boundary 4
- 131 132-1035 1036-4890 4891

- 159254 NOlES: 1_ Data represent USGS E-PEST**~igh)** eslirTDtes at cj the county level from 1992 to 2009. 2. NAWQAsurfacewater data avaiiWiefrom 2D051o 2010_ Kiometers 0 250 500 

### le • I AMVAC CHEMICAL CORP_ NEWPORT BEACH, CALIFORNIA DRINKINGWATERASSESSMENT DICROTOPHOS OBSERVATIONS VERSUS ESllMATED USE
FIGURE

## ~ARCADlS X

As there are some detections outside ofthe expected boundaries for productuse, which indicates thatthere maybe some false positives inthe survey, which suggests that actual exposure maybe lowerthan that indicated by the dataset. It is recognizedthat there is some uncertainty in determiningpeakwater concentrations from monitoring data due to limitations in sampling frequency. However, when the objective is set at determining an average water concentration over a longerperiod, monitoring data becomes much more rigorous. In the case ofdicrotophos, the exposure period associated with the toxicologically significant cholinesterase pointofdeparture is reached at 21 days. Monitoring data would be expectedto provide a reasonable assessment ofaverage concentration values within such an extendedperiod.

Page 18 of34A preliminary assessment ofthe monitoring data indicates that exposure to dicrotophos in surface water is very low. Within the entire collection ofsampling sites, there are only 57 detections (<1% ofthe sampling) with measureable residues. With one exception, all residues are at concentration levels that are less than 0.3 ppb, a level that is 2.7X lower than what was predicted for sub-chronic risk in baseline modeling using PRZM/EXAMS.

Figure3-4 Distribution ofNAWQA Surface Water Concentrations for Dicrotophos

_r::_._ Monitoring from: 112005 to 12/2010 8,831 results

.. 99.45% <LOD 0.65% detected 1result >0.3 ppb

Futher corroboration thatthe average 21-day exposure would be at low levels is provided by examiningthe finding at the one site in Washington County., Mississippi, where residues exceeded 0.3 ppb. This occurred in a single sampling event. Sampling was also taken on the subsequent day and the residue concentration in this sample was more than an order of magnitude lower. These findings maybe evidence that at higher dicrotophos concentrations are very short-lived in the environemnt; therefore they would nothave a very significant impact on the average 21-dayresidue concentration.

Page 19 of34

### 3.5.4 Location of HighestMeasuredDicrotophos Concentration in NAWQA Data Set
Figure 3-5 Map Location ofHighestMeasured Concentration ofDicrotophos within NA WQA SurfaceWater Sampling Sites

. 

# . -r**,,.,~ ~,~**  ,';,Jkoi,.,_;._-.,**'/."·~-m~~** .··!1:1•.**~}**

t .J'tt**f..,A ~**  -:;)t'.>ltl J«H-:-

...**;:~·~-trp1** H.l'"tl**hAdifi~;..:l';Jj_j-,** J. { 'i'fh'l**!~ .:~-~** 

NAWQA Diaotophos Result :!iJ; non-detect !if detect Cropland Data**Laye~** L.Jeotton otherwale!Way stream D 1lkliglHU NOl"ES: 1.CllUongiO'IWBg areasbased on USilA. CroplandDala layer-{all} in 2005 witherimated use..-accuHic:y>95%.

Page 20 of34 _,....·**Vrl->.Jd:>ti'·l~H<··** ''-.,**YN+N·}U~:<;:j'**

JW,VAC CHEMICAL CORP. NEWPORT BEACH, CALIFORNIA 001\!Ka'lGWA l"ERASSESSIIBIT lOCA110N OF MAXIMUM DICROlOPHOS RESUlT

### ~ARCADIS fiGURE X

### 3.5.5 DischargeRates vs. ResidueDetections atSite of HighestDicrotophos Concentration
Figure3-6 Discharge Ratevs. Dicrotophos Residue Concentration atthe NA WQA Site of HighestResidue Concentration

"0 c: c u Q) (4 1008 '- Q) a.**~** Q) Q)


### .... u ·.-I ..c ::l u ' Q)**~** '- ttl ..c: u**~?** ;3 108
)- ..J H 

### USGS 07288650 BOGUE PHALIA NR LELAND, MS

a: c**8 ~---=~mmmmwm~--.m** ....**mmmmmmmmBmmmemmmwm.mmmwmwm~** Jul 02 Jul 09 Jul 16 Jul 23 Jul 30 Aug 06 Aug 13 Aug 20 Aug 27**280~ 200~** **288~ 280~** **208~ 280~** **280~ 200~** **200~**

--- Daily nean discharge**~** Period of approved data



### http://waterdata.usgs.gov/nwis/dv?cb 00065=on&cb 00060=on&cb OOOlO=on&cb 00095=on &format=gif default&site no=07288650&referred module=sw&period=&begin date=2005- 07-0l&end date=2005-08-30

Further, a more detailed analysis ofthis site by ARCADIS 

### reveals thatthe peak detection was not associated with discharge rates at the sampling site. As demonstrated in the following section, dicrotophos surface water concentrations are primarily impacted byrunoff. Normally, higher discharge rates would promote the movement ofresidues from fields to surface water bodies. The lack ofa relationship betweenthese parameters challenges the reliability ofthe analytical result showing the peak detection at this site. Also, the fact that there was only one detection ofthis magnitude and no intermediate detections within a one magnitude range below this detection within the entire survey challenges the relevance ofthis single finding.

Page 21 of34

### 3.5.6 Relative Contributions of DriftandRunoff forDicrotophosSurface Water Concentrations To assess the relative sensitivity ofthe EDWCs to spray drift and runoff, a sensitivity analysis was performed. For this effort, the baseline spray drift fraction of0.016 in the baseline assessmentwas reduced by 50% (0.08) in one scenario and no spray drift was assigned within the second scenario. There are only modest decreases in surface water concentrations by modifyingthe driftparameter and the contribution ofspray drift to the yearly concentration is less than 20%. Although the modeled concentrations do not include 21-day average values, the annual values attest to the sensitivity ofthe parameter and demonstrate that runoffwould likely be the dominating factor contributing to dicrotophos residues in surface water.

Table3-7 Sensitivity ofParent Compound EDWCs to Spray Drift Sensitivity of Parent Compound EDWCs

## to Decreasing Spray. Drift .to50%and 0% of Baseline11 1-irf-10Yeai"Values (ppb)31 Peak 30-Yr Yearly. Avg. 10.80 0.65 0.35 10.20 0.59 0.29 9.54 0.53 10.00 0.84 0.39 9.41 0.78 0.33 -6.0 8.78 0.71 0.26**.,12~~-** 13.10 0.76 0.38 Cotton 12.40 0.69 0.31 -5.3 10.80 0.62 0.25
1/ Modeling performed with Surface Water Concentration Calculator (SWCC) utilizing a percent crop treatment factor of33% 2/ Per EPA standard baseline drift set to 0.016 for aerial spray application. 30-Yr Avg.**~18.20**

3/ Shaded values indicate;::: 10% reduction in EDWCs relative to baseline scenario

Page 22 of34I Table 3-8 Sensitivity ofTotal Toxic Residues EDWCs to Spray Drift Sensitivity ofTotal Toxic Residue EDWCs,to Decreasing Spray Drift

. to 50% and 0% of Baseline11 

## swcc Sensitivity 1-in-10Year Values (ppb)31 % Reduction31 Crop. Analysis21 . 30-Yr 30-Yr Peak Yearly Peak Yearly Scenario Scenario Avg. Avg.**-~** .\ MS Baseline 11.00 0.81 0.43 SO% drift 10.30 0.74 0.36 -6.06 -9.15 •...c16.40 Cotton

. . . //**d~.s:·** 

### 1:> '-3;:t3 0% Drift 9.64 0.66 0.29 <; ;-12.1 •·•·• Baseline 11.00 1.09 0.50 NC
•••••• 50% drift 10.20 1.01 0.42 6.9 -7.7 

## :-fs.s Cottoni 

### 0% Drift 9.50 0.92 0.34 ·..·7'13.s·•··

### n:.·.~~~-s 

# .1< 

### .:3iA

.. Baseline 13.70 0.97 0.49 TX 50% drift 12.80 0.88 0.40 -6.5 -9.2 '-;t;7.8 •• Cotton •. 0%Drift i:;..12Jf'**~l~.ti;**

### lt·~~?A 11.90 0.80 0.32
1/ Modeling performed with Surface Water Concentration Calculator (SWCC) utilizing a percent crop treatment factor of33% 2/ Per EPA standard baseline drift set to 0.016 for aerial spray application. 3/ Shaded values**indicate~** 10% reduction in EDWCs relative to baseline scenario



### 3.5. 7 

### Refinementof Surface Water ExposureandResultingAggregateExposure Risk Overall the monitoring data setreflects dicrotophos concentrations of0.3 ppb or less. Bytaking the conservative step ofadopting this value to represent the 21-day average concentration and conducting a refined aggregate risk assessment, there are no exceedances associated with the 95th percentile sub-chronic risk for any ofthe three EPA scenarios. It should be noted thatthese calculations represent approximate values as the assessment assumes that all ofthe exposure is due to surface water, when in fact there is a very small contribution by cottonseed oil. However, this effect is negligible and does not change the findings ofthe analysis. A comparison ofEPA's steady state dietary exposure analysis based onPRZMIEXAMS modeling withthatbased on conservative use ofthe NAWQA monitoring data set is provided below for maximum and typical use rates in MS, TX, andNC.

Page 23 of34Table 3-9 Dicrotophos Steady StateDietary Exposure forMS at Cotton Maximum Rate
Results ofSteady State Dietary Exposure Analysis for Dicrotophos (Food and Drinking Water} MSCottoli Maximum Rate

·······• .··. •. Population Subgroup

General US Population Alllnfants(<1 year old) Children 1-2years old Children 3"5 years old Children 6-12 years old Youth 13-19 years old Adults 20-49 years old Adults**50~99** years old Females 13-49years·old PRZM/EXAMS ChronicWater, Conservative NAWQA Monitoring Data Water Concentration0.80 ppb PAD ••·. Concentration 0.30ppb 95th Percentile (mkd)**J-,-~.,.--'--~--__,...--..;.;_•-+~.;.;.....,.-9_5t_h,..P_e_r_ce..,..n~t-ile_..,....----l** Exposure % PAD1; 

### < Exposure %PAD1/ •··.··. (mkd) (mkd) •·.··
·.. 0.000277 92 0.000104 35 0.000632

. 210 •(

# >0.000237 79 0.000367 ·, 12.2 > .. 

## i 0.000138 46

...... 0.000315 105 ;. {;';', 0.000118 39 0.0003 0.000258 86 0.000097 32 0.000237 79 0.000089 30 0.000277 92 0.000104 35 0.000228 76 0.000086 28**.·.··~-------r------------r-------+-----------~** .• 0.000281 93 0.000105 35
1/%PAD textthat is in bold reflects exceedances

Table3-10 Dicrotophos Steady State Dietary Exposure forMS at Cotton TypicalRate R«;!sLJits ofSteady State Dietary Exposure Analysis for Dicrotophos

(Food and Drinking Water) · .•, •.. MS CottonTypical Rate < ·

....• Conservative NAWO.A PRZM/EXAMS Chronic Water Monitoring Data\fiJater Concentration 0.80 ppb ·

. Population Subgroup PAD 95th Percentile' Concentration 0.39 ppb (mkd) 95th Percentile Exposure 

### ... Exposure

••• •••• (mkd) % pA[)l/


### ... (mkd) %

## PAD11

.. General U.S. Population . · 0.000206 69 0.000077 26 All Infants {<1 year old) 0.000399 ·. · .. 

## .**i~gi• ~~it**  ;j?;; 0.000150 49 Children1-2 years old 0.000262 87 0.000098 33 Children 3-5 years old

# 00~~ 0.000149 76 0.000056 29 Children 6-12 years old 0.000145 66 0.000054 25 Youth 13,-19 years old 0.000144 65 0.000054 24 Adults**20~49** years old 0.000116 69 0.000044 26 Adults 50-99 years old 0.000228 53 0.000086 20 Females B--49years old 0.000146 69 0.000055 26
1/%PAD textthat is in bold reflects exceedances

Page 24 of34Table 3-11 Dicrotophos Steady State Dietary Exposure for NC at Cotton Maximum Rate
Results ofSteady State DietaryExposure Analysi$ for Dicrotophos

.. .

,, (Foodand DrinkingWater} , NC Cotton Maximum Rate ,:·
. . ...·. Conservative NAWQA PRZM/EXAMSChronic Water Monitoring Data Water .,'PAD Concentration 0_80 ppb Concentration 0.30 ppb PopulationSubgroup 95th Percentile (rnkd) '· 95th Percentile Exposure < %PAD11 Exposure % PAD11 ' {mkd)
.·. (mkd) General. U.S. Population 0.000265 88 0.000099 33 Alllnfants(<lyear old) 0.00059

### :~~ 

## ·<;2oo·

..:;;, 0.000221 75 Children 1,.2 years old ····· ·,.. 0.000356 

# \'ui;.e: •[l20. 

### .;> 0.000134 45 Children 3-5 years old I 0.000302 100 0.000113 38 Children 6-12 years old 0.0003 0.00025 83 0.000094 31 Youth 13-19years old 0.00023 77 0.000086 29 Adults 20-49 years old 0.000263 88 0.000099 33 Adults 50-99 years old 0.000215 72 0.000081 27 Females**13~49** years old 0.000265 88 . 0.000099 33
l11%PAD textthat is in bold reflects exceedances

Table 3-12 Dicrotophos Steady StateDietary Exposure forMS at Cotton Typical Rate

:**,~esults** ofSteadyState Dietary ExposureAnalysis for Dicrotophos (Food and Drinking Water) NCCotton Typical Rate

...... . ., Conservative NAWQA

. PRZM/EXAMS Chronic Water ' Concentration 0.80 ppb Monitoring Data Water Population Subgroup .·· PAD 95th Percentile Concentration 0.30 ppb

•••••• (mkd) , ..

· 95th Percentile Exposure .· % PAD11 Exposure % PAD11 '
·····
. ., (mkd) : ·' (mkd)

- GeneraiU.S. Population 0.000197 66 0.000074 25 All Infants (<1 year old) 0.000369 I

.. .120.•. 

### ' 

### .,: 0.000138 45

. Childrenl-2years old / 0.000251 84 0.000094 32 Childreh3-5 years old 0.000219 73 0.000082 27 Children 6-12years old 0.0003 0.000196 65 0.000074 24 Youth 13-19years old ,•·•••• ,, 0.000195 65 0.000073 .· 24**Adults20~49** years old 0.000197 66 0.000074 25 Adults**50~99** years old ··: 0.000156 52 0.000059 20

••••••••••••• Females 13-49 years old .•, •. > 0.000197 66 0.000074 25
l11%PAD textthat is in bold reflects exceedances

Page 25 of34Table3-13 Dicrotophos Steady StateDietary Exposure for TX at Cotton Maximum Rate
' Results ofSteady State Dietary Exposure Analysisfor Dicrotophos <

. ,. (Food and Drinking Water) TX Cotton Maximum Rate

..... Conservative NAWQA ·, PRZM/EXAMS ChronicWater .·· Concentration0.80 ppb MonitoringDataWater PAO Concentration 0.30 ppb ···

.. PopulationSubgroup 95th Percentile (mkd) '·

... .,· 95th Percentile ·' Exposure % PAD11

.·.·· Exposure % PAD11 (mkd)

.········

.. .. (mkd) General U.S. Population ·.·· 0.000261 87 0.000098 33 All Infants (<1 year old) 0.000573 

## · .. , ..•.

. 

## ":

...... 

## ····. i90·': .; 0.000215 71 Children 1-2yearsold 0.000345 . · ... ·**~20** 

### .. 

## k:: 0.000129 45 Children**3~5years** old

. 0.000244 81 0.000092 30 Childrerl6-12years old ... 0.0003 0.000245 82 0.000092 31 Youth 13-19yearsold 

## ",: 0.000225 75 0.000084 28 Adults 20-49years old 0.000259 86 0.000097 32 Adults50-99yearsold 0.00021 70 0.000079 26 Females 13-49years old 0.000264 88 0.000099 33
1/%PAD text that is in bold reflects exceedances

Table3-14 Dicrotophos Steady State Dietary Exposure for TX at Cotton Typical Rate
Results ofSteady State Dietary Exposure Analysis for Oicrot()phos ':· .'·

.., (Foodand DrinkingWater) TX.Cotton Typical.Rate · . .·.··':,, PRZM/EXAM$ Chronic Water Conservative NAWOA ·.·'.

... . . Concentration 0.80 ppb Monitor'ingDataWater ., Population Subgroup PAD 95th Percentile Concentration 030 ppb (mkd) ·,. 95th Percentile Exposure % PAD11 Exposure % PAD11

....,. (mkd) (mkd) General US Population 0.000197 66 0.000074 25 Alllnfants(<1yearold) 0.00036 .<';. ::**1~{).~:<** 

### .·· 0.000135 45 Children 1-2years old 0.000246 82 0.000092 31 Children 38years old

••••• 0.000217 72 0.000081 27 Children 6-12years old 0.0003 0.000196 65 0.000074 24 Youth 13-19years old ..•,. 0.000195 65 0.000073 24 Adults 20-49 years old 0.000196 65 0.000074 24

. . Adults 50-,99 years old '· 0.000157 52 0.000059 20 Females BA9years old'•• 0.000197 66 0.000074 25 j1;%PAD textthat is in bold reflects exceedances

Page 26 of34

### 4.0 SPECIFIC COMMENTS The comments below are specific to inconsistencies, errors, orissues identified in the text ofthe cited documents. Page numbers andparagraph numbers are providedto assist the reviewer in locating the specific information, and recommendations are made for adjustments.



### 4.1.1 EPA memorandum of July 10, 2014: (PC Code: 035201; DPBarcode393772); "Dicrotophos: Drinking WaterAssessment forReregistrationReview", by AndrewShelby (Physical Scientist) EnvironmentalRiskBranch 6. 1. Within the opening section, 1stpp., EPA states, "Given currentuncertainty, the following degradates are included in the TTR approach:"

AMV AC's comment: Several metabolites listed as a component ofthe residue of toxicological concern are not appropriate for inclusion. AMY AC agrees withthe Agency's approach ofincluding metabolites/degradates formed from dicrotophos for which an organophosphate structural component is maintained whenthere is an absence ofdata concerningthe toxicological characteristics ofthe compound. However, inclusion ofcompounds that do not maintain this structural feature should be excluded. Such compounds would notbe predictedto inhibit cholinesterase activity, which is the mechanism oftoxicity that is being considered in the risk assessment. Therefore, even if these compounds were to have toxicological properties, combiningthe residues in an assessment for cholinesterase inhibition is not appropriate. Compounds that should be excluded from the grouping ofresidues used for the cholinesterase inhibition-based assessment are the**~-oxo-amides** SD 6167 and SD11733. 2. Within the opening section, 1stpp., EPA states, "Based onmodelingresults, the maximum estimated surface water exposure concentrations for total toxic residues of dicrotophos and assuming maximum application rates for currentuses are: 12.44 11g/L for the 1 in 10 year annual peakconcentration 0.80 11g/L for the l-in- 10 year annual average, and 0.4lllg/L for the 30 year annual average" [Note typographical error with inconsistencies in punctuation]

AMVAC's comment: Aside from our comment concerningthe definition oftotal residues oftoxicological concern, it is importantto note that this assessment is not fully refined and does not consider exposure estimates that would be relevantto the current label with its associated mitigation measures. Also, within PRZM-EXAMS modeling, the important inputparameter for aerobic aquatic metabolism utilizes a subjective policybased correction factor to account for limitations in the dataset. This approach should be recognized as beinghighly conservative as there is no data that would indicate that the actual half-life would be extendedto this extent. For these reasons, the modeling described in this document should be referred to as a screening level assessment.

Page 27 of343. Within the opening section, 1stpp., EPA states, "Based on modelingresults, the maximum estimated groundwater exposure concentration for total toxic residues of dicrotophos is 0.05 (SCIGROW) to 0.06 Jlg/L (PRZM-GW) for acute and chronic exposure."

AMVAC's comment: Aside from our commentconcerning the definition oftotal residues oftoxicological concern, it is importantto note that this assessment is not fully refined and does not consider exposure estimates that would be associated with the current label and its associated mitigation measures. Also, within PRZM-EXAMS modeling, the important inputparameter for aerobic aquatic metabolism utilizes a subjectivepolicybased correction factor to account for limitations in the dataset. This approach shouldbe recognized as being highly conservative as there is no data that would indicate thatthe actual half-life wouldbe extendedto this extent. Forthese reasons, the modeling described in this document shouldbe referred to as a screening level assessment.

4. Within the section "Fate and Transport Characterization", 1stpp., EPA states, "Dicrotophos is relatively more persistentto hydrolysis with a half-life of72 days (MRID 160823)." AMVAC's comment: The Agency might clarifythatthis half-life is associatedwith neutral pH conditions.
5. Within the section "Fate and Transport Characterization", 1stpp., EPA states, "Dicrotophos is stable to hydrolysis (MRID 160824)." AMV AC's comment: We believe thatthe Agency is intending to referto photolysis in aqueous solution, not hydrolysis.
6. Within the section "Drinking Water Exposure Modeling", Table 1., EPA states, "Table 1. PRZMIEXAMS inputparametervalues for dicrotophos. Use on cotton andtree injections." AMVAC's comment: The use on cotton beingmodeled is for aerial application andthat should bereflected in the title.
7. Within the section "Drinking Water Exposure Modeling", Table 1., EPA states, "(AnRf study indicates SD 6167 is likelymore mobile thanparent dicrotophos [MRID 160829]."

AMV AC's comment: The mobility ofthe**~-oxo-amide** SD 6167 SD shouldbe considered irrelevantto an exposure assessment for dicrotophos for reasons previously stated; thus the note should be removed from the table.

Page 28 of348. Withinthe section "DrinkingWater Exposure Modeling", Table 1., EPA states, "Hydrolysis Half-life (days) 72 (parent) 990 (TTR)" AMVAC's comment: The inclusion ofthe**~-oxo-amide** SD 6167 has an effect onthe half-life value associated with the TTR. For reasons previously stated, it is not appropriate to include this compound in the exposure assessment. On day 28 ofthe hydrolysis study utilized in this assessment, residues ofthis component accounted for 4.8% ofthe total radioactive residue in the pH 7 test system. Inclusion ofthis residue yields inappropriate bias in the assessment. 9. Withinthe section "DrinkingWater Exposure Modeling", Table 1., EPA states, "Aerobic Soil Metabolism Half-life (days) 8.1 (parent) 8.7 (TTR)" AMVAC's comment: The inclusion ofthe**~-oxo-amide** SD 6167 has an effect on the half-life value associated with the TTR. Forreasons previously stated, it is not appropriate to include this compound in the exposure assessment. Residues associated with SD 6167 represent the difference in the values between the assessment for parent compound and for TTR. Therefore, inclusion ofthis residue yields inappropriate bias in the assessment. 10. Withinthe section "DrinkingWaterExposure Modeling", pp.6, EPA states, "The modeling ofparent only and typical rates is performed for characterization and should be considered for quantitative purposes with the caveat thatthe values are not conservative in all cases. For instance, the parent onlytypical use rate EDWC for cotton in Mississippi is 5.85 ppb. However, monitoring data indicate that concentrations of6.83 ppb occurred in Mississippi in 2005 when dicrotophos had the same use pattern and rates as modeled in this assessment. Though the next highest detection was less than 0.3 ppb, one detection is indicative that similar concentrations could occur in other surface waters or atthe same site at a different time but are not recorded. This monitoring data is derived from a targeted effort on the Boque Phalian a cotton predominantwatershed, in which dicrotophos concentrations were determined approximately every 14 days."
AMVAC's comment: It is not appropriate to place any significance on a single "high" sampling finding amongst a overall NA WQAIPDP database comprised ofca. 8,500 samples. There are no residues even with the range ofan order ofmagnitude below this value, which indicates that this value may be an outlier and may notbe reflective ofthe real distribution. What is most notable is the finding that residues ofdicrotophos in surface water, including waters in targeted sites, produce a consistentpattern oflow level exposures. This provides strong assurance thatthere is only low level exposure to dicrotophos in drinking water from surface water sources, even without any water treatment or conditioning.

11. Withinthe section "DrinkingWater Exposure Modeling", pp.6, EPA states, "As concentrations varywithweather, application patterns and subsequent dissipation, the Page 29 of34likelihood ofcapturing the peak concentration diminishes with a sampling interval of 14 days. Based on an analysis ofa more complete monitoring dataset for atrazine, the average bias factor on a sampling interval of 14 days for estimating a 60-day rolling mean was approximately 4 with a 95% confidence interval ofapproximately 7 (SAP, 2012). Due to differences in exposure window and the variability in field conditions, these bias factors cannotbe directly applied to dicrotophos monitoring data though they would likely be higher when estimating an acute concentration and lower for an annual average. However, the bias factors illustrate the uncertainty associated with identifying 6.83 ppb as the highest concentration occurring in dicrotophos use areas. Given these uncertainties, the use ofEDWCs derived from typical rates and/orparent only model simulations should onlybe done with caution and the awareness that it may not conservativelyrepresent dicrotophos concentrations in all documented instances."
AMVAC's comment: We agree that the sampling interval associatedwith field monitoring is critical to defining peak concentrations at specific sites. However, when the assessment is applied to an extensive survey such as the ca, 8,500 sample as associated with the NA WQA/PDP database, abetter indication ofpeak concentration levels can be achieved. Further, for a compound such as dicrotophos that appears to rapidly dissipate in awater compartment, it is likely that the measured chemical concentration in the grab sample would be higher than the concentration at the time ofexposure to a consumer, although this reduction factor has not been defined. We also find that utilizingthe atrazine dataset for estimatingthe peak level concentration for dicrotophos is unreliable, especiallywhen the bias factor is being applied to a single samplingresult. Further, the environmental fate attributes and use practices ofthe herbicide atrazine are different from that ofthe insecticide dicrotophos; so applying surrogate bias factors is not well supported. Finally, it is also important to recognize thatthe fact that the single "high" sample concentration of6.83 ppb appears to be an outlier within the distribution may indicate that the finding is attributable to some form ofproduct misuse or a site spill. As indicated earlier in this report, there is also a question concerning the integrity ofthis result as there was notthe expected correlation between discharge rate and analytical concentration. Therefore, without additional information, it is not appropriate to assert any significant meaning to this isolated finding.

Page 30 of34

### 4.1.2 EPA memorandum of July 10, 2014: (PC Code: 035201; DPBarcodeD418103); "Dicrotophos:AcuteandSteady StateAggregateDietary (Food andDrinking**wate1~** 

### Exposure andRiskAssessments to SupportRegistration Review", by Thurston Morton (Chemist) RiskAssessmentBranch IV, Health Effects Division (7509P). 1. Within the "Executive Summary" section, "Steady State Dietary (Food and Drinking Water) Exposure results and Characterization", 2ndpp., EPA states, "An unrefined steady state dietary exposure assessmentwas conducted to estimate the dietary risks associatedwiththe registration ofdicrotophos. The steady state dietary exposure assessment incorporated tolerance level residues and 100% crop treated. The steady state aggregate dietary exposure estimates from Calendex are above RED's level ofconcern(> 100% ofthe PAD) for the U.S. population and all population subgroups. Combined dietary exposure from food and drinking water is 136% ofthe PAD for the U.S. population and 358% ofthe PAD for children 1-2 years, the most highly exposed population subgroup." AMVAC's comment: We have already confirmed with EPAthat these values are in error and the highest exposed subpopulation group is the all infants (<1 year old). The combined dietary exposure from food and drinking water at the 95th percentile for the U.S. population ranges from 66 to 92% ofthePAD, which does not exceed RED's level ofconcern. The combined dietary exposure from food and drinking water atthe 95th percentile for the all infants (<1 year old) population subgroup ranges from 120 to 210% ofthe PAD, which exceed RED's level ofconcern. As EPA has indicated, these exceedances result in a slight overestimation ofexposure as the assessment assumes tolerance level residues and 100% crop treated. Also, water exposure is based on a screening level assessment ofsurface water exposure using PRZMIEXAMS that canbe refined as indicatedpreviously in this document.
2. Within the "IV. Drinking WaterData" section, 1stpp., EPA states, "This assessment uses maximumrates but considers typical rates though monitoring data exceeds the resulting EDWCs in some instances." AMVAC's comment: The only EDWC exceedance ofwhich we are aware is the single NA WQA sample finding of6.83 ppb outofa database of8,500 samples. These fmdings, especially when considered on the basis a statistical distribution would indicate that the PAD would notbe exceeded or at most only at a probabilistic level exceedingthe 99.9th percentile.
3. Within the "IV. Drinking Water Data" section, 1stpp., EPA states, "The assessment considers aparent only approach butalso considers the major degradates as parent in a total toxic residue (TRR) approach."

AMVAC's comment: Within our comments to the EPA memorandum ofJuly 10,2014: (PC Code: 035201; DP Barcode 393772); "Dicrotophos: Drinking Water Assessmentfor Reregistration Review", by Andrew Shelby (Physical Scientist) Environmental Risk Page 31 of34Branch 6, we explained our views for proposingthatthe total toxic residue definition be redefined to exclude metabolites/degradates that do not maintain an organophosphatebased structural functionality. On this basis, the EDWC exceedances overstate exposure. 4. Within the "N. Drinking WaterData" section, 1stpp., EPA states, "Given current uncertainty, he following degradates are included in the TTR approach:" AMVAC's comment: The referenced information is notprovided.
5. Within the "VI. CALENDEX-DCID Program" section, 2nd pp., EPA states, "RED's steady state assessment considers the potential risk from a 21-day exposure duration using a 3-weekrolling average (sliding byday) across the year. Forthis assessment, the same food residue values used in the acute assessment were used for the 21-day duration. In the Calendex, one diary for each individual in the WWEIA is selected to be paired with a randomly selected set ofresidue values for each food consumed. Forthe water residue values, Calendex incorporates PRZM-EXAMs drinking water residue by selecting a year at random from those available in the designated drinking waterresidue file." AMVAC's comment: Although the process being used by RED represents a reasonable initial screening approach, the availability ofa large surface water monitoring database that includes targeted samplingprovides an opportunity for refining the water exposurebased and aggregate risk assessments.
6. Within the "VIII. Results/Discussion" section, 2ndpp., EPA states, "For food and drinking water, the acute dietary risk estimate is belowRED's level ofconcern at the 99.91h percentile ofexposure. The acute dietary exposure using DEEMwas estimated for the U.S. population is 13% ofthe aPAD and 27% for all infants (<1 yrs old), the most highly exposedpopulation subgroup. The steady state aggregate dietary (food and drinking water) exposure estimates using Calendex are above RED's level ofconcern for the U.S. population and all population subgroups. Combined dietary exposure from food and drinking water is 136% ofPAD for the U.S. population and 358% ofthe PAD for children 1-2 years, the most highly exposedpopulation subgroup." AMV AC's comment: Based on conversations with EPA, we have confirmed that the information within this text is incorrect and refers to that ofanother chemical.
7. Within the "IX. Characterization ofInputs/Outputs" section, 1stpp., EPA states, "RED hass conducted unrefined acute and steady state dietary risk assessments for coumaphos. OPs exhibit aphenomenon known as steady state Ache inhibition and for coumaphos a steady state endpointwas selected. Although, there are rat data at a shorter period (i.e., 15 days) than 21 days, exposure assessments of21 days and longer were conducted for all routes ofexposure (i.e., oral, dermal and inhalation) for all single chemical OP assessments using Calendex. Given this, the 21-day and longer exposure assessment is scientifically supportable and also provides consistency across the OPs."

Page 32 of34AMVAC's comment: Based on conversations withEPA, we have confirmedthat the inf01mation within this text is incorrect and refers to that ofanother chemical.
8. Withinthe "X. Conclusions" section, 1stpp., EPA states, "these unrefined analyses demonstrate that the requested uses for dicrotophos will notresult in acute dietary risk estimates that exceed HED's level ofconcern for any ofthe regulated population subgroups, including those comprised ofinfants and children." 9. AMVAC's comment: The acute dietary risk estimates atthe 95thpercentile does not exceeds the aPAD for any ofthe subpopulation groups. This would indicate that acute aggregate exposure would not ofconcern.

Page 33 of34

### 5.0 REFERENCES USED IN THE ASSESSMENTS

ESRI. 2014. ArcGIS Desktop: Release 10. Redlands, CA: Environmental Systems Research Institute. G.P. Thelin and W.W. Stone. (2013). Estimation ofAnnual Agricultural Pesticides Use for Counties ofthe Conterminous United States, 1992-2009, Scientific Investigation Report 2013-5009. [Online]. Available: http:/ /pubs.usgs.gov/sir/20 13/5009/pdf/sir20135009.pdf USDA 2006. Mississippi Cropland Data Layer for 2005. U.S. Department ofAgriculture (USDA), National Agricultural Statistics Service (NASS), Research and Development Division (RDD), Geospatial Information Branch (GIB), Spatial Analysis Research Section (SARS), Washington, D.C. [Online]. Available: http:/ /www.nass.usda.gov/research/Cropland/metadata!metadata

_ms05.htm USEPA. 2006. Data quality assessment: Statistical methods for practitioners, EPA/240/B06/003 [Online]. Available: http://www.epa.gov/QUALITY/qs-docs/g9sfinal.pdf USEPA. 2013. ProUCL Version 5.0.00 Technical Guide, EPA/600/R-07/041 [Online]. Available: http://www.epa.gov/osp/hstl/tsc/ProUCL v5.0 tech.pdf USGS. 2009. National Water QualityAssessment (NAWQA) Database. U.S. Geological Survey, Washington, DC. [Online]. Available: http:/ /water.usgs.gov/nawqa/about.html [Accessed: 18-Nov-2014] USGS. 2014. USGS Stream Gage Station ID 07288650 at Bogue Phalia nearLeland, MS. [Online]. Available: http://waterdata.usgs.gov/nwis/nwismap/?site no=07288650&agency cd=USGS

Page 34 of34

# Appendix 3STUDY TITLE Response to EPA's Preliminary EnvironmentalFate and Ecological RiskAssessment for Dicrotophos

TEST GUIDELINE: None

AUTHORS: R. Scott Teed1 Colleen Greer2 Gillian Manning 1 DickFreedlander3

STUDY COMPLETION DATE: November 28, 2014 PERFORMING COMPANIES:
1 IntrinsikEnvironmental Sciences, Inc. 1125 Colonel By Drive CarletonUniversity Campus CTTC

- Suite 2600 2IntrinsikEnvironmental Sciences (US), Inc.

Ottawa, ONK1 S 5R1 CumberlandHall (Pineland) 41 Campus Drive, Suite 202 New Gloucester, ME 04260

PROJECT NUMBER: Intrinsik Project#60-60625 AMVAC Report##800-REV-021

PREPARED FOR: 3AMV AC Chemical Corporation 4695 MacArthur Court, Suite 1200 NewportBeach, CA 92660 TOTAL PAGES: 56

Page 1 of56NO CLAIM OF CONFIDENTIALITY No claim ofconfidentiality, on any basis whatsoever, is made for any information contained in this document. I acknowledge that information not designated as within the scope ofFIFRA sec. 1

0(d)(1)(A), (B), or (C) and which pertains to a registered or previously registered pesticide is not entitled to confidential treatment and may be released to the public, subject to the provisions regarding disclosureto multinational entities under FIFRA 1 O(g).

Company: AMVAC Chemical Corporation

CompanyAgent: Dick Freedlander Director Environmental Sciences AMVAC Chemical Corporation

Signature:

# ---~...__-=----------=------- Date: \ \ \ 

## 2-55 J 

# z..n\'-\**------~---------------**

Page 2 of56GOOD LABORATORY PRACTICE COMPLIANCE This study does not fall under EPA FIFRA Good Laboratory Practice (GLP) Standards set forth inTitle 40, Part 160 ofthe Code ofFederal Regulations.

Submitter:

Signature: Date: DickFreedlander Director Environmental Sciences AMV AC Chemical Corporation

Page 3 of56TABLE OF CONTENTS

1.0 EXECUTIVE SUMMARY

............................................................................................................... 5 2.0 INTRODUCTION

............................................................................................................................7 3.0 GENERAL COMMENTS

................................................................................................................ 8 3.1 Use Patterns

.................................................................................................................................. 8 3.2 Selection ofScreening-level Effects Metrics

................................................................................ 8 3.2.1 Birds andMammals

.............................................................................................................. 8 3.3 Exposure Modeling

.......................................................................................................................9 3.3.1 AgDrift

................................................................................................................................ 10 3.3.2 T-REX

................................................................................................................................. 12 3.3.3 STIR

.................................................................................................................................... 16 3.3.4 SIP

....................................................................................................................................... l7 3.4 Supporting Documentation

......................................................................................................... 18 3.4.1 Refined Deterministic Assessment

..................................................................................... 18 3.4.2 Incident Reports

..................................................................................................................21 3.4.3 Field Studies

........................................................................................................................22 3.5 Conclusions

.................................................................................................................................23 4.0 SPECIFIC COMMENTS

................................................................................................................25 5.0 REFERENCES

...............................................................................................................................41

List ofTables Table 2-1 Summary ofriskquotientresults for birds and mammals associated with cotton fields

.... 20 List ofAppendices APPENDIXA RefinedDeterministic Total Daily Intake Models for Birds and Mammals thatFrequent CottonFields

...............................................................................................................................................46 APPENDIX B EllS IncidentReports for Dicrotophos

...............................................................................54

Page 4 of561.0 Executive Summary Dicrotophos is a systemic broad spectrum organophosphate insecticide. It is currently manufacturedbyAMV AC Chemical Corporation (AMV AC) under the trade name Bidrin 8 and Bidrin XP II. The current AMV AC label for dicrotophos is limitedto use oncotton. Recently, the Environmental ProtectionAgency (EPA), Office ofPesticide Programs provided a screeninglevel ecological risk assessment (ERA) for dicrotophos that looked at environmental fate and risk to plants and wildlife (EPA, 2014). The ERA is highly conservative and suggests thatuse of dicrotophos in cotton fields maybe ofconcern to birds and mammals (EPA, 2014). TheAgency used a weight-of-evidence approach when drawing these conclusions. The Agency applied the highly conservative screening-level toolbox models (e.g. T-REX, T-HERPS, SIP, STIR) and reviewed additional information on incidentreports and field studyresults. The Agencyconclusions in the ERA report (EPA, 2014) suggestthere maybe risk to birds and mammals, and terrestrial invertebrates. Therefore, given the highly conservative assumptions used inthis screen, a more refinedrisk characterization is required. In this report, Intrinsik Environmental Sciences Inc. (Intrinsik) and AMV ACprovide examples ofappropriate refinements for risk characterization. For example, by substitutingthe default screening level foliar dissipation decline with a more appropriate pattern relevantto dicrotophos; using a more refined free metabolic rate (FMR) approachin the total daily intake models in place ofthe baseline food intake rate (FIR) approach used in T-REX; and, byrecognizing the metabolic patterns associated with dicrotophos, a somewhatmore refined deterministic risk assessment is provided for several mammalian and avian focus species. These results yielded risk quotients that were significantly lower thanthose calculated bythe Agency (EPA, 2014): Species Refined Risk T-REX Short Quotient (RQ) Grass RQa Indigo bunting (Passerina cyanea) 3.0 463.3 Northern cardinal (Cardinalis cardinalis) 0.9 463.3 American widgeon (Anas americana) 1.5 65.8 Female meadow vole (Microtuspennsylvanicus) 5.6 9.8 Male meadowvole (Microtuspennsylvanicus) 4.1 9.8 Female deer (Odocoileus virginianus) 1.6 5.2 Male deer (Odocoileus virginianus) 1.1 5.2

a - Based onthe short grass RQ calculated for the appropnate we1ght class ofeach ofthe spec1es l!sted. The current set ofrefinements that are described in this report do nottake into account other important considerations that would further lower the RQ values. For example, the extent of cotton field utilization for foraging by different animal species for which datathat are readily available inthe field studies for dicrotophos. Also, recovery from exposure effects due to dicrotophos should be taken into account. As with most acetylcholinesterase inhibitors, exposed organisms that do not exceed an exposure concentrationthat leads to mortalitywill recover rapidly from the exposure. A review ofthe remaining weight ofevidence in the Agency's assessmentrefines the Agency's initial assessment. Given that cotton fields do notprovide a good source ofnutrition to most

Page 5 of56animal species provides in itselfsome rationale as to why this use would not impactwildlife. Although field studies have been conducted in the pastto assess the potential impact of dicrotophos use in cotton on avian species, these study results were confounded by the concurrent use ofmany other chemicals ofpotential toxicological concern, including organophosphates that were applied to the same treated fields. The reported incident reports in the EllS and the peerreviewed literature suggestthat the primary cause ofavian and mammalian mortality is human error and illegal use ofthe product. In addition, only one incident was associated with cotton use (all other use patterns have been removed from the label) and according to the incident database, it was unlikely to be associated with dicrotophos use. Overall, refined modeling and important ancillary informationprovides a basis for concluding that dicrotophos use on cotton would notpose an unacceptable ecological terrestrial riskto avian and mammalian species.

Page 6 of56

### 2.0 INTRODUCTION The Environmental Protection Agency (EPA) released their PreliminaryEnvironmental Fate and Ecological Risk Assessment (ERA) for the Registration ofDicrotophos in July, 2014. In that report the Agency outlined their preliminary ecological risk assessment conducted byEPA under the Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA) for registration review of dicrotophos. Dicrotophos is a systemic broad spectrum organophosphate insecticide with a mode ofaction that interferes with the acetylcholinesterase enzyme (AChE). AMVAC Chemical Corporation (AMVAC) currentlymanufactures two end-use products that contain dicrotophos; Bidrin® 8 (82% dicrotophos) and BidrinXP 

### IITM (50.7% dicrotophos 

### + 11.2% bifenthrin). Bidrin® 8 and BidrinXP 

### II are onlyproposed for use on cotton through both aerial and ground application. Aspart ofthe registration reviewprocess, AMV AC has retained Intrinsik Environmental Sciences Inc. (Intrinsik) tojointlyreview the preliminary ERA for dicrotophos with respect to the potentialrisks to birds and mammals. AMV AC and Intrinsik have a number ofcomments with regard to EPA'spreliminaryERA contained inthis report. The report has two main sections. Section 2 provides general comments onthe approaches used bythe Agency in developing their exposure, effects, and risk characterization. Additional analyses are provided in Section 2 for consideration bythe Agency. Section 3 contains specific comments on the report includingtypographic errors, data or calculation errors, and other specific comments and recommendations.

Page 7 of56

### 3.0 GENERAL COMMENTS The following general comments address key issues thatAMV AC and Intrinsik have identified within EPA's preliminary ERA. 3.1 Use Patterns There have been significant changes to the usepatterns for dicrotophos since it was first registered in the United States. AMV AC is currently only supporting use on cotton andhas implemented significant mitigation measures on the labels. Therefore much ofthe historical information onmonitoring data, incidentreports, and field study results (EPA, 2014) do not providetheproper contextfor current dicrotophos use. Care mustbe taken in the use ofthis type ofevidence when discussing the potential risk ofdicrotophos use on cotton. This is discussed further in the report. 3.2 Selection ofScreening-level Effects Metrics 3.2.1 BirdsandMammals The avian effects metrics used byEPA (20 14) were based onpastregistrant submitted studies. For example Shell Research Ltd. submitted a study byDoyle and Elsea (1963) [MRID 00013439] to the Agency in 1966. The study was conducted with domestic goose (Anser anser), a non-guideline species andhad the lowest oral dose (LD50) ofthe studies surveyed. However, the dose was administered once via stomach tube and the response was either no effect (0% mortality) or 100%mortality at an order ofmagnitude higher dose (0.385 to 3.85 mg ai/kg bw). Estimation ofan LD50 with no intervening exposure concentrations is uncertain and dependent uponthe model used to estimatethe dose-response relationship.
A closerreview ofthe selected acute effect metric for domestic goose used in the assessment suggests thatthere are many deficiencies inthe study (Doyle and Elsea (1963)) [MRID 00013439]. The study didnotfollow Good Laboratory Practice (GLP), which is a reflection of the age ofthe study. It is unclear from the reportwhether a standard guideline orprotocol was followed. Similarly, the study lacks details on study design and conditions, andprocessing ofthe results. For instance, the tested chemical was not properly characterized. The age, sex and weight ofthe birds were notreported, and it is unknown whetherthe geese were acclimatedpriorto testing. Basictestconditions such as light intensity, photoperiod andtemperature were not reported. Moreover, the report didnot state whether controls were used. Lastly, the statistical procedure for evaluating results was not reported. As a result, this study is insufficient in terms ofdatareporting in accordance with OPP's evaluation guidelines (EPA, 2011a). Additionally, the goose study was selected because it appeared to be the most sensitive endpoint available. With consideration ofusing this endpoint for predictingthe LD50 for a much smaller bird, the Mineaubody scaling factor (EPA, 2012a) cannotbe calculated since animal weight in

Page 8 of56the goose study was not reported. Relationships between body weight and toxicity as predicted by the Mineau scaling factor for dicrotophos are herein called into question (see Section 2.3.2). Stomachtube or oral gavage exposure pathways do not accuratelyreflect exposure ofbirds and mammals inthe field (ECOFRAM, 1999). In gavage studies, the effects ofdietary matrices, feeding patterns, metabolism, and elimination throughout the day are not accounted for. The fact that dietary LD50s are generally much higher than gavage LD50s is attributed to these factors. EPA (2014) also presentedrisk results based on dietary exposures. Typical guideline acute dietary studies have a five day exposure period followed bythree days ofobservation. However, the toxicity study selectedbyEPA (20 14) was actually 28 days in length. This is more representative ofa chronic exposure period and would likelyresult in a lower LC50. Comparison ofa five day environmental exposure concentration (EEC) to an effect metric from a 28 day chronic effect metric would result in a significant overestimation ofrisk. 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 atthe nexthighest treatment level (3 ppm). However, an 8% reduction in female bodyweight should notbe considered ecologicallyrelevant as such small changes would reflect natural variability. Certainly, minor reductions in bodyweight 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 onlytwice 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). Overall, the avian effects metrics chosenbyEPA (2014) for their preliminaryERA were overly conservative, utilized certain studies with important data deficiencies, and not consistent with conditions expected in the field. Further, a more recent literature study on starlings provides a betterbasis for calculating dose-based dietary risk (Grue and Shipley, 1984). Within this study, the LD50s for sensitive starling nestlings and adults were determinedto be 4.92 and 8.37, respectively. This studyprovides sufficient detail for validating the findings. Althoughthere is a betterbasis for assessing dose-based exposure, a more accurate assessment canbe developed by selecting effects metrics that are dietary-based and demonstrate significant effects beyond what wouldbe predicted by natural variability. 3.3 Exposure Modeling EPA used their standard screening-level modeling toolbox to evaluate dicrotophos. These models can be found at http://www.epa.gov/oppefedllmode1s/terrestrial/. These models are intended to be highly conservative and serve as a screento determine whether a more refined assessment is required. This approach generally uses a comparison ofa very sensitive effect metric to peak modeled EEC to generate a risk quotient (RQ). Risk quotients are then comparedto EPA's levels

Page 9 of56ofconcern (LOCs) for threatened and endangered species (listed species) and non-listed species to characterize risk. A briefdiscussion ofthe models and theirparameterization is provided in this section. 3.3.1 AgDrift IntheirpreliminaryERA, EPA (2014) uses AgDRIFT® (v.2.1.1) to model potential risk to birds and mammals to dicrotophos exposure from spray drift. 

### In this document are a number of comments with regard to the spray drift model used to determine buffer distances for protection oflisted and non-listed species. Empirical data from the Spray Drift Task Force (SDTF) used to develop AgDRIFT® for ground spray and orchard airblast were collected in the early 1990s. The nozzles and application equipmentused in these studies nowrepresent oldertechnology, as they have been improved overthe last 20 years to reduce drift. The aerial component ofAgDRIFT® is an earlierversion ofAgDISP®, which was developed in 2002. Therefore, the built-in equipment scenarios represent nozzles and equipment no longer in general practice and used more than a decade ago. Crop Life America (CLA) submitted comments onthe AgDRIFT model and associated guidance "Consideration ofSpray Drift in Pesticide RiskAssessment" (docketEPA-HQ-0 PP-2013-0676) to the Agency in 2013 (Leggett, 2014). AMVAC agrees withthese comments and a summary of these comments is providedbelow:

• The default scenarios for ground and aerial applications are atypical and offer few or no refinement options. Model parameters rarely reflect common agricultural practice for any ofthe application categories described.

• AgDRIFT® relies exclusively on SDTF data collected over20 years ago. The SDTF did not conduct applicator surveys to determine which application equipment or operating parameters were in common use, and instead selected nozzles and sprayers that represented the worst-case situation for drift. Thus, the studies were designed to overpredict drift atthe time they were conducted. These data are useful in defining what an upper-bound ofexposure mightbe, butthe distribution ofdata should notbe assumed to representthe distributionthat wouldbe observed from typical application practices used today.

• Agriculture and Agri-Food Canada (AAFC) have recentlyproduced high quality deposition data sets similar to those ofthe SDTF. AAFC trials were conducted in 2000, 2004, 2006, and 2011, and included the use ofmore contemporary application equipment, including drift-reducing nozzle technologies. EPA has, so far, not consideredthese data due to the lack ofquality assurance/quality control (QA/QC). CLA is committedto providingthe QA/QC verification necessary for EPAto include the AAFC data in their decision making. EPA should include current information andbest-available data when making registration decisions.

Page 10 of56• AgDRIFT® fits the SDTF data to a Gaussian curve, which is a weakpredictor ofthe data at distance from the field edge. In usingthe Gaussian model, drift never dissipates completely, which is intuitively flawed.

• SDTF datawere combined in broad categories to generate drift curves applicable to all products. This eliminates the possibility offactoring in label mitigation options such as restrictions ofdroplet size in ground applications ormitigation bywind speed. Although not done in AgDRIFT®, it is possible to use F-testmethodologies to determine which data sets maybe combined to generate appropriate categories.

• For ground application, AgDRIFT® assumes that the contribution ofresidues from successive passes is additive up to 20 swaths. This assumption needs to be examined because it exacerbates the tendency ofdrift curves to over-estimate drift at farther distances offthe field.

• The ability to conductrisk assessments for ground and orchard air-blast applications is currentlyrestricted to AgDRIFT® Tier 1 and there is no opportunityto run more refined risk assessments at higher tiers.

• RegDISP is a modification ofAgDISP® thatpredicts spray drift deposition from ground applications ofpesticides. Spray drift is calculated based onregression equations constructed from more recent empirical field data obtained from AAFC in addition to older data from the SDTF. The user can choose from the above-mentioned datasets by selecting study year, nozzle, boom height, sprayer speed, andwind speed. RegDISP also allows users to inputregression equations constructed from their own data sets. RegDISP has been integrated with AgDISP® so that the user can choose whetherto run AgDISP® for aerial applications or RegDISP for ground applications. Once a deposition equation has been selected, RegDISP estimates deposition as the fraction applied, and the deposition and stream assessmenttools developed as part ofthe AgDISP interface canbe run bythe user. RegDISP has been shownto muchmore accuratelypredict spray drift than AgDRIFT®. The use ofthe AgDRIFT® model produces exaggerated over-predictions ofdrift for off-site movement ofdicrotophos spray droplets in air, especially beyond 300 m from the treated field. AMV AC recommends thatEPA:

• consider current best available data in estimating drift deposition;

• evaluate and applyRegDISP for regulatory use;

• select model inputparameters thatreflectreasonable label-adherence, instead ofworstcase assumptions;

• provide a complete accounting ofall inputparameters used in the spray driftmodel(s);
Page 11 of56• provide a discussion ofthe uncertainties and limitations ofthe drift model(s) used; if AgDRIFT® is used, conductthe exposure assessment only at distances that have been validated using empirical data and are considered acceptable by EPA (2004b, 2005); and

• consider applying a correction factor to the predicted deposition based on the known overestimation ofAgDRIFT®. 

### 3.3.2 Jr-Jll?)( The Terrestrial Residue Exposure Model (T-REX) is a wildlife exposure model that is primarily used to assess riskto birds and mammals. T-REX (v.1.5) was used to estimate terrestrial EECs onfood items in the Agency's ERA (EPA, 2014). However, T-REX has a number oflimitations and uncertainties that are listedbelow and canbe addressed through the use ofmore refined modeling as provided in this report.

• T-REX assumes birds and mammals forage 100% ofthe time onthe treated field and thus their complete dietary intake comes from the treated field. This is highly conservative because most mobile species will forage on and offthe field throughout a given day. This reduces the overall exposure experienced by the animal. However in T-REX, the maximum possible cumulative daily peak exposure is assumed.

• The T-REX model conservatively assumes thatwildlife obtain 100% oftheir diet from pesticide-treated locations immediately following application. Although this may be reasonable for a generic screening, the assumption is not applicable to all wildlife. Sullivan and Wisk (2012) illustrated howthis assumption is improbable for manythreatened and endangeredbirds by compiling foraging habitat data for the 89 listed species found in US states orterritories. They found that less than 25% ofbird species considered occurred adjacentto agricultural areas, with the largest percentage (37%) ofspecies found foraging solely in forested habitat.

• Kenaga nomograms (Fletcher et al. 1994; Hoerger and Kenaga, 1972) are the basis ofresidue unit doses (RUDs) in T-REX. They are upper bound values that are derived from datathat do not reflect currentpesticide applications (i.e., nozzles) and are notpesticide-specific. The use ofthese RUDs lead to an overestimate ofexposure for dicrotophos in particular whenthe default foliar DT50 of35 days is applied. Dicrotophos is knownto rapidly degrade thereby reducing the availability ofthe pesticide compared to the average values available in T-REX.

• T-REX assumes the animal eats 100% ofa particular feed item (e.g., short grass). This is highly conservative because most species eat a varied diet and different feed items will have different amounts ofresidues (e.g., short grass has higher residues than seeds). Forthe short grass diet inparticular, the modeled consumption ofpesticide residues is muchhigher than the average because very few species subsist solely on short grass.

Page 12 of56• The size classes considered in T-REX include 20, 100, and 1000 g birds, and 15, 35, and 1000 g mammals. It is unlikely that grasses (short and tall) and broadleaffoliage alone could provide sufficient energy for smaller wildlife species, consideringthe caloric needs of smaller animals on a cal/kg basis, and the time and energy demands ofthe foraging required to meet those needs. This deficiency is mentioned in the T-REX user manual withrespect to short grass and the smallestweight class ofbirds and mammals. Forthreatened and endangered bird species, Sullivan and Wisk (2012) found that only one ofthe 89 threatened and endangered species they considered consume primarily grasses at any period in time (Hawaiian geese**(~**1500 g), in the winter). Thus, as short grass typically has the highest residue unit doses (RUD), exposure is considerably overestimated for birds and mammals (whether listed or non-listed). None ofthe other listed species evaluated by Sullivan and Wisk (2012) consumed only grasses and/or broadleaffoliage.

• Residues are expected to differ among feed item categories. EPAhas recognized that pesticide residues onterrestrial invertebrates can vary considerably, and have conducted refined exposure assessments (e.g., for wildlife consuming earthworms (EPA, 2007; EPA, 2009a-d)). Forrealistic dietary exposure estimates, residues should be quantified for flying insects, surface and crop-dwelling arthropods, and soil-invertebrates, such as earthworms. Ideally, these estimates would be derived with end-use-product-specific data. However, it is recognized that ample arthropod residue data for pesticides such as dicrotophos are often lacking to derive pesticide-specific RUDs.

• T-REX uses food intake rates that do not account for the assimilation efficiencies ofthe dietary items (i.e., some foods have higher energy content, whichrequires less consumption to attain required energy for survival). This results inhigher food consumption than is probable in nature, thus increasing modeled exposure.

• Food ingestion rate is estimated in T-REX with allometric equations derived from Nagy et al. (1987). However, more up-to-date estimates offield metabolic rates are available (Nagy et al., 1999) that include numerous bird species (n=95, compared to n=50 in Nagyetal. (1987)). Further, T-REX does not account for differences in assimilation efficiencies ofthe dietary items. This is an important consideration as the amount ofenergy obtained in the diet can vary depending onthe feed item, which may impact overall food ingestionrates ofan individual. Forexample, feeding the same dietary concentrationto animals during toxicity testing does notnecessarily lead to the same exposure for the same receptor species due to differences in food ingestion rates among species, bodyweights and diets. Therefore, average body weights and feed consumption shouldbe used to calculate dietary endpoints used for TREX modeling (i.e., units ofmg ai/kgbw/day).

• T-REX uses allometric scaling to calculate adjusted toxicityvalues for avian and mammalian species. 

### In ecological risk assessments, the toxicity ofchemicals to avian and mammalian

Page 13 of56wildlife is typically based on effects data derived from a limited number oflaboratory species. Allometric scaling oftoxicity data is an approach used by wildlife risk assessors to extrapolate toxic effects from species with data (i.e., test species) to species without (i.e., the wildlife receptors assessed inthe risk assessment process). The use ofallometric scaling in the interspecies extrapolation oftoxicity data is based on the observation that numerous physiological processes directly associated with metabolism (e.g., uptake, distribution, biotransformation) are related to organismal responses to chemicals and follow a predictable relationship with bodymass (Travis and White, 1988; Chappell, 1992; Mineau et al., 1996, Sample and Arenal, 1999). The slope ofthe line linkingtoxicity to bodymass is equivocal and extrapolations based onbodymass raised to the power of0.6 to 1.5 have been suggested for use as toxicity scaling factors among species (e.g., for birds see Mineau et al., 1996; Sample and Arenal, 1999; for mammals see Davidson et al., 1986; Travis and White, 1988; Chappell, 1992; Sample et al., 1996; Bokkers and Slob, 2007). Support for the use ofallometric scaling in the calculation ofadjusted toxicity values for avian and mammalian species is provided in the EPA's T-REX guidance manual (EPA, 2012a). Forbirds, acute toxicitytest results (LD50) can be modified to an "adjusted LD50" following Equation 1where "x" is EFED's recommended default, the Mineaubird scaling factor of 1.15 (Mineau et al., 1996).
Body l1lGSSSpecies ofInterest LD50Speciesoflnlerest

## =LD50TestSpecies ( ) x-1 Body massTest Species Equation 1

Withthis scaling factor, sensitivity is inversely related to body size (i.e., smaller birds are more sensitive than larger ones). EPA notes thatthe Mineau scaling factor canbe replaced by a chemical-specific scaling factor ifdata are available. A value of 1.0 (a slope indicative ofno relationship with mass) can be entered ifthe assessorbelieves that bodymass will not influence chemicaltoxicity. No method for the adjustment ofchronic avian toxicity data is recommended byEPA (2012a). Formammals, the same equation (Equation 1) 1 is used to derive an adjusted toxicity metric with the bird-specific Mineau scaling factor replaced by a scaling factor of0.75. The mammalian equation leads to the opposite resultproduced with birds (i.e., smaller mammals are less sensitive than larger ones). Unlike for birds, however, EPA-EFED allows for adjustment to chronic mammalian toxicity using the same approach exceptthatthe acute LD50 term is replaced bythe chronic no observed adverse effect level (NOAEL). Mineau et al. (1996)

1 Readers shouldnote that inT-REX guidance manual the numerator and denominator from Equation 1 are inverted between birds and mammals. As a result, the exponents inthe equations are different. Inbirds it is x-1, with x being the Mineau scaling factor. With mammals, a value of0.25 is reported byEPA, which is the resulting value of 1-x, with x beingthe mammalian scaling factor of0.75.
Page 14 of56recommended a specific scaling factor of 1.118 for dicrotophos. However, the Agency used the default scaling factor of 1.15 in its ERA (EPA, 2014). Use ofthe scaling factor to extrapolate to very large mammals from typicallyrattoxicity study results is not recommended due to the significantuncertainty associated withthat extrapolation. The application ofallometric scalingto pesticidetoxicity data is not without its drawbacks: allometric scaling is mostuseful for like chemicals with similar dispositions (Davidson et al., 1986; Chappell, 1992) and may not be applicable to wide range of chemicals; the use ofallometric scaling maynot be appropriate for chemicals that undergo biotransformation as the toxicity ofmetabolites may differ from parent compounds (Travis and White, 1988; EPA, 20 11a); and almostall data linking allometric scaling to toxicity have done so using acute or sub-chronic data so the relationship to chronic data is lacking empirical support (Knopper et al., 2009). Although EPA allows for some level ofadjustment, this guidance is not always applied inpractice for pesticides. For example, for two organophosphate pesticides, dimethoate andmalathion, both ofwhich are transformed in vivo to equally or more toxic oxons, EPA has applied generic allometric scaling in their effects determination (EPA, 2008). The inappropriate use ofallometric scaling canresult in erroneous conclusions 

### in risk assessments due to unsupported toxicity metrics. Also, and most importantly, dicrotophos, unlike many other organophosphates, is an oxon-based species; thus metabolismprimarily leads to nontoxic species. Therefore, AMV AC believes that no scaling factor (i.e. scaling factor of 1) should be applied for dicrotophos for birds. The chronic risk estimation for dicrotophos in the T-REX model is incorrectbecause this model compares peakacute exposure estimates to chronic toxicityNOELs, which is a mismatch oftoxicity endpoints and EECs. This approach significantly exaggerates the potential riskposedby non-persistent compounds such as dicrotophos. Exposure durations in chronic avian and mammalian studies are typically greaterthan 10 weeks (EPA, 1998a,b; 2012b). However, such exposures are unrealistic because dicrotophos degrades rapidly between applications, making pulse exposures far more relevant than maintained chronic exposure. Inthe absence ofrealistic pulse exposure toxicity data, EPA should consider including chronic averaging in T-REX to account for dicrotophos degradation between applications.

• The use ofNOELs/NOAELs, orNOECs/NOAECs for evaluating chronic risks to non-target organisms has many shortcomings, includingbeing very sensitive to study dose selection and sample size. It is for this reason and others that the OECD and otherjurisdictions (including EPA's HED) have moved towards regression analysis to generate acute and chronic effects metrics rather than rely onhypothesis testing.

Page 15 of56• EPA (2014) has statedthat dicrotophos is expected to degrade quickly in terrestrial environments (EPA, 2014- Section 2.5.2), but used a default degradation half-life of35 days in T-REX. Although no foliar dissipation data are readily available, the soil degradation and field dissipation half-lives are 2.7 and 2.2 days, respectively. Therefore, use ofdegradation half-life that is more than an order ofmagnitude longer than other degradation half-lives available inthe current literature is extremely conservative and overestimates the availability ofdicrotophos on food items. The dislodgeable foliar residue data that are available to the Agency demonstrates that residues decline with a half-life established at two different field sites ofless than 2.33 days (Prochaska, 1978) [MRID 44728501]. It is recognized that these data do not account for the possibilityofa different decline profile for residues that are not dislodged. Therefore, relative abundance ofsurface basedresidues versus residues withinthe target plant system is not clearly understood. In spite ofa lack ofcertain information, EPA's designation ofa 35- day foliar half-life for modelingpurposes is likely to be highly exaggerated. EPA has commentedonthis point and conducted a sensitivity analysis assuming a three day foliar half-life. The Agency determined thatthere was a 40% reduction in the RQs (e.g., 5.82 to 3.44); but stated, "However, even ifthe data were available to reduce the foliar dissipation half-life used in the model to three days, all size class and forage class exceedances would remain, albeit not as far off-field as for the 35-day half-life assumption." Although this may be true, the inclusion ofthis refinementwhen combined with otherrefinements (e.g. free metabolic rate (FMR) approach, foraging time inthe field, etc.) would significantly lower the potential exposure to dicrotophos foliar residues. For example, it is well recognized that animals do not utilize a diet comprised fully ofshort grass; therefore further refinements in the risk assessment canbe performed, which in combinationwith a more accurate foliar halflife would yield RQs that are significantly lower. This is illustrated in Appendix A using species that are known to be associated with agricultural landscapes where cotton is grown. In conclusion, T-REX (v.1.5.2) is highly conservative and overestimates direct dietary exposure ofterrestrial species. Although T-REX (v.1.5.2) estimates risk for birds andmammals ofvarious sizes, each feed item category is not necessarilyrelevant to every size class. Furthermore, TREX does not account for differences in gross energy and assimilation efficiencies ofthe dietary items ofbirds and mammals. Therefore, appropriate allometric field metabolic rate (FMR) considerations, more realistic diets for bird species that frequent cotton landscapes, and appropriate chronic averaging for exposure modeling should be considered in refined modeling along with a weight-of-evidence evaluationto develop a refined risk characterization. Many of these refinements andrecommendations can also be found in the peerreviewed literature (e.g. Brain et al. 2014). 3.3.3 STIR The Screening Tool for Inhalation Risk (STIR v.l.O) was used by EPA (2014) to estimate the risk to birds and mammals from inhalation ofdicrotophos. Itwas determined that inhalation of

Page 16 of56dicrotophos poses a potential risk to birds and mammals on an acute exposure basis. However, EPA (2014) used an unbounded LC50 (>0.059 mg/L, MRID 46411001) for inhalation of dicrotophos by rats in STIR. The use ofan unbounded effects metric is entirely inappropriate and it is unclear ifany effects were observed atthe highesttest concentration. The true LC50 maybe orders ofmagnitude higherthan that used byEPA (2014) in STIR. Additionally, EPA (20 14) clearly states that dicrotophos is non-volatile (vaporpressure of7.0 x10·5 torr and Henry's law constant of3.13 x10· 11 atm-m3 /mol). Therefore, acute risk to birds from inhalation ofdicrotophos is highly uncertain and likely much lower than thatmodeled by EPA (20 14). 

### 3.3.4 jiJJ> The Screening ImbibitionProgram (SIP) was used inthe assessment as a screen for bird and mammal consumption ofdrinking waterthat may contain dicrotophos. The results ofthe SIP analysis suggestedthat dicrotophos exposure in drinking water is a potential concern for both birds and mammals. The SIP model employs the following assumptions to derive upper bound exposure estimates (EPA, 2010): 1. The chemical concentration in drinking water is at the solubility limit in water (at 25°C). 2. The assessed animals obtain 100% oftheir dailywaterneeds through drinking water. 3. The daily water need is equivalentto the daily water flux rate as calculated by Nagy and Peterson (1988). 4. The body weight ofthe assessed bird is equivalentto the smallest generic bird modeled in T-REX (i.e., 20 g). This assumption results inthe highestratio ofexposure to toxicity for the 3 assessed avian body weights ofT-REX (i.e., 20, 100, 1000 g). 5. The body weight ofthe assessed mammal is equivalentto the largest generic mammal modeled in T-REX (i.e., 1000 g). This results in the highestratio ofexposure to toxicity for the 3 assessed mammalianbodyweights ofT-REX (i.e., 15, 35, 1000 g). The assumptions made in the model (1 to 5) are overly conservative andunrealistic. It is highly unlikely that drinkingwaterfound on a treated field would ever contain a pesticide at its solubility limit. Fordicrotophos the water solubility usedbythe Agency was 11,990 mg/L [MRID 43603202]. However, this does nottake into account the applicationrate applied (which would limit the mass ofdicrotophos onthe field), dissipationkinetics on the field, and the unlikely scenario that applicators would apply dicrotophosjustpriorto or during a rain eventthat would result in standing water on the field. Further, utilizing the solubility limitfor a chemical that is highly water soluble is inappropriate as the concentration inthe field begins to rival the chemical application ofa unit area. Inaddition, birds satisfy some oftheir water needs by oxidative food metabolism and excrete nitrogen as uric acid instead ofurea (unlike mammals)(EPA, 1993). Lastly, both birds (20 g) and mammals (1000 g) in the weight classes evaluated in SIP are highly mobile and are unlikely to get all ofthe daily drinking water needs from one treated field. It is more likely theirpesticide intake wouldbe the result ofspatial averaging from potentially many fields (treated and non-treated) and untreated offfield habitats.

Page 17 of56Therefore, SIP is designed to very significantly overestimate the contribution ofdrinking water to the overall total daily intake ofa pesticide for birds or mammals.
A more reasonable and appropriate approachto deriving conservative drinking water estimates is the Pesticide RootZone Model (PRZM) edge offield predictions at the field edge. These estimates are generated by PRZM for use in the Exposure Analysis Modeling System (EXAMs) model to estimate water concentrations in the EPA standard pond scenarios. The edge-of-field flux estimates provide consideration ofthe environmental fate properties ofa pesticide to predict transport and transformation through crop root and unsaturated soil zones. As such theyprovide more reasonable estimates ofdrinkingwater as a source ofexposure. 3.4 Supporting Documentation 

### 3.4.1 RefinedDeterministicAssessment The Agency's use ofT-REXto conduct mammal and bird screening-level risk assessments resulted in an overly conservative risk estimate for these taxa, and indirectly for terrestrial phase amphibians and reptiles where birds were used as a surrogate. To demonstrate howmore realistic assumptions can affect the risk characterization for these taxa, a refined deterministic assessment was conducted for birds and mammals that are known to be present in cotton agricultural landscapes that include cotton. This refined deterministic analysis was also conducted using an FMR approach ratherthan the FIR approach used in T-REX. Lastly, the refined analysis was run with both a 35 day (default) foliar degradation DT50 and a 3 day foliar DT50. The Agency performedthe same analysis intheir dicrotophos ERA (EPA, 2014) although there is clear evidence that suggest a 3 day DT50 is more appropriate thatthe 35 day default value. The bird species selected for this analysis include the Indigo bunting 

### (Passerina cyanea), Northern cardinal 

### (Cardinalis cardinalis), and American wigeon 

### (AnasAmericana). All three species are known to be associated with cotton landscapes (Sheeley et al. 1988) and represent different body weights and diets. Formammals, the meadow vole 

### (Microtuspennsylvanicus) and white-tailed deer 

### (Odocoileus virginianus) were selected both ofwhich are commonly found in agricultural landscapes. Details on diets, bodyweights and other parameters selected are provided in Appendix A. The conservative, refined deterministic total daily intake (TDI) modeling was carried outto estimate acute dicrotophos exposure from use on cotton. The form ofa standard TDI model is (EPA, 1993):

k 

### TDI 

## = PT

# *INFIRi

# * ci Equation 1 i=l

Page 18 of56where, 

### PTis the proportion oftime in treated fields (unitless) NFIRi is the normalized food intake rate (kgfood/kg bw/day) 

### C is the concentration ofdicrotophos in each dietary item (i) (mg/kg) 

### Pi is the assumed dailyproportion ofthe i th dietary item by mass k is the number offood items in the diet (unitless)

Measured FIR are typically not available for mostwildlife receptors, primarily due to the difficulties in measuring intake for free-ranging animals (EPA, 1993). Measured food intake rates determined using captive animals should notbe used because such animals do not expend energy foraging for food and water, avoiding predators, defending territories, etc. (EPA, 1993). Thus, food intake rates estimated for captive animals considerablyunderestimate expected food intake rates for free-ranging animals. There are also issues with establishing accurate preconsumption dry and wet weight orvolume measurements from stomach content analyses. Instead, for most receptors an allometric equation developed from measurements ofFMR in freeranging animals best estimates food intake rates. The normalized food intake rate (NFIRi) ofthe lhfood item is derived from the normalized FMR using the following equation:



### FEi 

### * NFMR NF/Ri 

## = ME· L where, NFMR is the free metabolic rate normalized to body weight (kcal/kg bw/day) MEi (=AEix GEi) is metabolizable free energy for the k 1h food item (kcal/kg) AEiis the assimilation efficiency ofthe lh food item (unitless) GEi is the gross energy ofthe lh food item (kcal/kg). Equation 2

The proportion offree energy (FEi) from each dietary item is calculated usingEquation 3:

Equation 3

The receptor specificparameters used in the exposure modeling are presented in Appendix A. Concentrations in feed items were estimatedusing the generic residue unit doses (RUDs) as presented in T-REX vl.5.2. Degradation onfeed items was modeled two ways, the first using the EPA default 35 day DT50 value for foliar degradation and secondusing a more realistic 3 day
Page 19 of56DT50 value. The peak dietary EEC values from T-REX v1.5.2 calculated based on the cotton exposure scenario (0.5 lb ailA I 2 applications I 14 day retreatment interval) were used in the calculations. Details calculations and results ofthe refined deterministic modeling are provided in Appendix A. Table 3-1 summarizes these results and compares the refined modeling results with the TREX v1.5.2 results as indicated in the EPA ERA (EPA, 2014). The effects metrics chosen to develop the RQs are from a study by Grue and Shipley (1984). Grue and Shipley (1984) examinedthe sensitivity ofEuropean starlings 

### (Sturnus vulgaris) to dicrotophos using an oral dose in administered in com oil. The authors examined brain and plasmaChE activity and recorded body weight and mortalities for each ofthe treatment levels. The authors determined the 24 hourmedian LD50 as 8.37 mglkg bwfor starling males and 8.47 mglkgbw for starling females. These LD50's were used in the risk assessment includingthe American wigeon evaluation as the domestic goose study is not considered an acceptable study for risk assessmentpurposes (see Section 2.2.1)

Table3-1 Summary ofrisk quotient results for birds and mammals associated with cotton fields Body weight Refined T-REXShort GrassRQ(Based Species Risk on ClosestBirdBody Weight (g) Quotient!' Category 

# ;a 35 day DTSO (T-REXdefault) Indigo bunting (Passerina cyanea) 14.50 8.7 463.3 Northern cardinal 44 1.61 463.3 (Cardinalis cardinalis) American widgeon (Anas americana) 756 2.5 65.8 Female meadowvole 33.8 5.6 9.8 (Microtuspennsylvanicus) Male meadow vole 33.8 4.7 9.8 (Microtuspennsylvanicus) Female deer 45000 2.7 5.2 (Odocoileus virginianus) Male deer 45000 1.9 5.2 (Odocoileus virginianus) 3 dayDTSO Indigo bunting (Passerina cyanea) 14.50 3.0 463.3 Northern cardinal 44 0.9 463.3 (Cardinalis cardinal is) American widgeon (Anas americana) 756.0 1.5 65.8 Female meadowvole 33.8 3.8 9.8 (Microtus**pennsylvanicu~** Male meadowvole 33.8 2.8 9.8 (Microtuspennsylvanicus) Female deer 45000 1.6 5.2 (Odocoileus virginianus)

Page 20 of56Table3-1 Summary ofrisk quotient results for birds and mammals associated with cotton fields Body weight Refined T-REXShort GrassRQ(Based Species Risk on ClosestBirdBody Weight (g) Quotienl Categoryt Male deer 45000 1.1 5.2 (Odocoileus virginianus) ' from EPA (2014) h Avianresults are based on tbe use ofthe adult starling LD50 or 8.37 mg/kg bw(Grue and Shipley (1984)) As can be seen in Table 3-1 all ofthe refined deterministic risk quotients with the exception of the white-tailed deer are lower than those predicted by T-REX 1.5.2. The higher results for the white-tailed deer are due to the mammalian scaling factor. The larger the mammal, the scaling factor adjusts sensitivityto make it more sensitive. T-REX only uses a 1000 g large mammal weight as one ofthe three weight classes, so the effect ofscaling factor is greater with a 45 kg deerthan a generic 1kg mammal. As previouslymentioned, there is significantuncertainty surrounding the use ofthe scalingfactors for both birds and mammals. The refined deterministic analysis uses conservative assumptions and the results indicate that exposure is overstated inthe Agency's ERA (EPA, 2014). A refined exposure assessment yields RQs ranging from 3.8 to 0.9 for the focal species assessed. Information contained inthis report indicates thatthese values can be further refined and are likely lowerthan the values herein presented. 

### 3.4.2 IncidentReports The ecological incident information system (EllS) evaluation outlines only five terrestrial incidents for dicrotophos and two aquatic incidents between 1976 and 2013 (Appendix B). A briefdiscussion ofthe terrestrial incidents are provided followed bythe aquatic incidents. One ofthe reported terrestrial incidents was classified in the EllS as a misuse ofthe product, resulting inthe loss of44 bee hives. Therefore, this incident was not considered further. The remaining four incidents occurredwithuse onrice, watermelon, a disposal site, and an unknown site. The use patterns for rice and watermelon have beenremoved from the label for dicrotophos. Information onthe disposal site incident is notprovided, but it is not a labelled crop use (i.e. cotton), andbecause it is a disposal site, it is likely due to mis-handling or illegal use ofa product containing dicrotophos. The final terrestrial incident did nothave a clearusepattern associated with it. However, it was labelled as beinghighlyprobable a result ofdicrotophos but the legality code was 'unknown'. Thus it is uncertain how dicrotophos was applied and to what purpose. The endresult was the loss of200 snow geese, a raptor, and a coyote. The fact that this incident is isolated indicates that the effect is not likelyrelated to a labeled agricultural use managed under good agricultural practices.

Page 21 of56The incidentreports in the EllS do not support a conclusionthatthere is a potential for direct effects from the use ofdicrotophos on cotton as none ofthe incidents were as a result oflegal use on cotton. EPApoints outthat the incident databases surveyed do not necessarily capture all incidents that may occur with a specific product due to the lack ofincidentreports, voluntary programs that collectthe information, under reporting ofnon-mortality incidents and a general lack ofresources to track incidents at the state and federal level. However, dicrotophos has been in use in the United States since 1956/7. Thus, over a potentialperiod ofapproximately 68 years, the small number ofreported EllS incidents andthe high uncertainty and legality codes assigned to the incidents suggest thatmis-use (not following the label) ormis-handling are the primary causes ofdicrotophos incidents in terrestrial environments. There are several reports in the literature that indicate dicrotophos has been intentionally and improperly used for poisoning of animals thatthreaten livestock and agricultural crops (e.g. Flickinger et al. 1984; Mitchell et al. 1984). In these cases baitwas treated with dicrotophos atexceptionallyhigh concentrations that would not be present in the environment from legal use. For example in Flickingeret al. (1984) rice treated for baitingpurposes was analyzed and had concentrations of210 ppm. Discriminating between intentionalpoisonings and effects due to legal productuse requires a verythorough investigation that is typically lacking within these incidentreports. It is well known that illnesses andpotentviral infections can lead to animal deaths. Because there is typically no autopsy orbiochemical/chemical analysis ofcarcasses in incidentreports, concludingthat isolated incidents are associated withpesticides simply onthe basis that animals have been found inproximityto chemical use is not sufficient for attributing chemical use to an incident. In summary, there is no pattern inthe incident reportingthat would suggestthat there are relevant detrimental ecological effects to terrestrial species associated with the legal use of dicrotophos on cotton. 

### 3.4.3 FieldStudies There are two avian field studies available for dicrotophos, reporting results for use on cotton in Alabama and Arizona (Palmer et al. 1988 [MRID 40873701]; Sheeley et al. 1988 [MRID 40917001]). Ourreview oftheAlabama field study finds that a meaningful interpretation ofthe study findings cannotbe accomplishedbecause ofthe confoundinguse ofmultiple insecticide products and significant differences in the use ofthese chemicals amongstthe different control and testplots. The finding ofresidues ofdicrotophos in certain carcasses simply connotes some level ofexposure that may or maynothave been lethal. Maintenance insecticides were apparently not analyzed within the study scope. Although some ofthe maintenance insecticides used in the study are consideredto have lower toxicity according to laboratory studies, any chemicals with characteristics ofeven moderate avian toxicity should not have been included in the testing. The effects ofsome ofthese moderately toxic chemicals have notbeentested inthe field. Most confounding to any study interpretation is the fact thatprofenphos (Curacron), malathion andmethyl parathion, three other organophosphate insecticides, were used onthe
Page 22 of56study plots. The phorphorthioate EPN was also used during the study. This compoundthat has since been cancelledhas also been shownto be highly toxic to avian species, especially passerines (Hill 1993). For these reasons, no scientifically valid interpretation ofthe effect of dicrotophos within the field study canbe made. The study findings can only be assessed in the context ofrelating the effects to a confluence ofdifferent agricultural materials.

Appendix VIII ofthe study report (Hill, 1993) contains a listing ofthe maintenance insecticides and their timing ofuse ofthe individual studyplots.

Hill, E.F. (1993) "Acute and sub-acute toxicology in evaluation ofpesticide hazard to avian wildlife" Up and Down Procedure PeerPanel Report; Appendix P-3 http:/ /ntp.niehs.nih.gov /iccvam/docs/acutetox docs/udpproc/udpfinO 1Iappend/appp3.pdf

The Arizona study (Palmer et al. 1988) was conducted in a similar manner to that ofthe Alabama study. Bothmalathion (llb ai/A) and chlorpyrifos (0.7lb ai/A) were used onthe testplots at signficiantlyhigher chemical applicationrates than the test substance dicrotophos (0.2 lb ai/A). As we concluded for the Alabama field study, no scientifically valid interpretation ofpotential dicrotophos effects can be made. However, avian effects to the different individual insecticides should be no worse than that observed inthis study. 

### 3.5 Conclusions The currentmodeling line ofevidence suggests thatpotential acute and chronic effects to birds due to dicrotophos use on cotton are overstated in the EPApreliminary ERA (EPA, 2014). The highly conservative nature ofthe screening-level ecological risk assessment conducted bythe Agencyprovides a basis for a more refined assessment, which for the currently labeleduse of dicrotophos on cotton demonstrates thatthe actual risk is significantly lower once othervariables are considered inthe risk assessment. A refined analysis that examined three bird species found in cotton landscapes, and took account actual dietary exposure is provided in this reportto support this finding. Similarly, the incident report line ofevidence provides no datato indicate that there is ecological risk to avian species from dicrotophos use on cotton. Instead, it suggests that human error through mis-use or mis-handling ofdicrotophos is the potential risk factor for birds. Unfortunately, the available field studies using dicrotophos were conducted inappropriately andprovide no useful information for assessingthe risk ofdicrotophos due to potential confounding effects ofthe otherpesticides applied to the study fields during the study. Formammals, the preliminary refined assessment for white-tailed deer and meadow vole indicate that acute risks are low relative to the results ofthe highly conservative screening-level

Page 23 of56model (T-REX) employed by the Agency. Similarly, the EPA also significantly overstated chronic effects due to the use ofthe the use ofthe predicted maximum residue on short grass and comparing to a chronic NOEL effectmetric. At a minimum an appropriate chronic EEC should be compared to the chronic effectmetric to evaluate the potential for chronic adverse effects. Particularly as nearly all wildlife in agro-ecosystems tend to forage in edge habitats rather than in treated fields (Best et al. 1990, 1995).

Page 24 of564.0 SPECIFIC COMMENTS The comments below are specific to inconsistencies, errors, or issues identified in the text ofthe EPAreport. Page numbers and paragraph numbers are provided to assistthe reviewer in locating the specific information, and recommendations are made for adjustments. The first set ofspecific comments are on the EPA memorandum (July 10, 2014). The second set ofspecific comments are onthe EPAERA itself(EPA, 2014). EPAMemorandum ofJuly 10, 2014: (PC Code: 035201; DP Barcode 393746); Transmittal ofthe Preliminary Environmental Fate and Ecological RiskAssessment for the Registration ofDicrotophos (Case#145) byAndrew Shelby (Physical Scientist) and Nathan Miller (Biologist) EnvironmentalRisk Branch 6. 1. Underthe section "Summary" 1stpp., EPA states, "In terms ofits chronic toxicity profile, chronic risks exceeding established levels ofconcern are identified for birds, mammals, and aquatic invertebrates for dicrotophos use on cotton." AMV AC's comment: While EPAhas identifiedpossible chronic risks ofconcerns, they are based on a screening level assessment and AMV AC has herein provided a more refined analysis. 2. Underthe section "Basic Uncertainties" 2ndpp., EPA states, "The occurrence of monocrotophos, a metabolite ofdicrotophos found in a cotton foliar residue study, in and/orplanttissue is a considerable uncertainty in the assessment. Monocrotophos is known to be more toxic to avian species than dicrotophos on an acute basis, and while residues ofmonocrotophos on foliage are presumedto be lesser (on a mass pervolume or massperunit area basis), the enhancedtoxicity ofthis compound may effectivelyextend the time ofacute risk LOC exceedances following dicrotophos application."

AMV AC's comment: The studythat we believe EPA is referring to is titled, "Dicrotophos and Monocrotophos inDislodgeable Foliar Residues on Cotton Leaves" and is indexed under MRID 44731002. Our interpretation ofthis study is that itvalidates ourviewthat 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 oftwo field sites and at the site located in Washington County, Mississippi. Detectable levels ofmonocrotophos were only measured attwo sampling intervals. The first finding was on the day ofthe 2nd application for which the arithmetic mean monocrotophos residue level was less thanthe limit ofquantification. The second finding was 4 days afterthe 3rd application for which the arithmetic mean monocrotophos residue level was 0.0145 ppm, less than 2Xthe limit ofquantitation

..Because the highesttotal residues occurred immediately following each application, the contribution ofmonocrotophos during these periods is negligible. Also,

Page 25 of56the labile nature ofthe monocrotophos residues would not support a contention thatthe enhanced activity ofmonocrotophos residues relative to dicrotophos residues would extend the time ofacute risk LOC exceedances in a meaningful way, given the significant differences in concentration between parent and metabolite. 3. In the title, "Table 1." EPAhas labeled the table as, "RiskResulting from Dicrotophos Exposure Presented byTaxon."

AMV AC's comment: As the ecological risk assessments are envisioned to be refined overtime, it wouldbe clearerto indicate when a risk table was developed using screening-level modeling and when a refined approach is used. Onthis basis, wepropose thatthe title be changedto, "Screening-Level RiskResulting from Dicrotophos Exposure PresentedbyTaxon". The following is a response by AMV AC Chemical Corporation concerningthe following EPA document: EPA's document, "Environmental fate and Ecological Risk Assessment for the Registration ofDicrotophos", July 10,2014: (PC Code: 035201); Andrew Shelby (Physical Scientist) and Nathan Miller (Biologist) Environmental Risk Branch 6. 1. Underthe section "Executive Summary" 3dpp., EPA states, "Aquatic exposure estimates for dicrotophos are presented for the parentcompound andtotal toxic residues (i.e., parent dicrotophosplustransformation products: SD 6167, SD 11733, and SD 228001)."

AMV AC's comment: Althoughthe butanamide degradates SD 6167 or SD 11733 may pose some undetermined level ofriskto certain aquatic species, these chemicals belong to a class ofcompounds that is distinct from the organophosphates. On this basis, these two metabolites should not be included inthe aquatic risk assessmentfor dicrotophos.

2. Underthe section "2.61 Residues ofConcern" 1stpp., EPA states, "Dicrotophos readily metabolizes to SD 6167 in aerobic soil". And, "Dicrotophos metabolizes to SD 11733 in anaerobic soil with concentrations as high as 12.7% ofappliedradioactivity at study conclusion (33 days)."

AMV AC's comment: When discussing the metabolism or degradation ofdicrotophos in the contextofSD 6167 and SD 11733 formation, it should be clarifiedthat these compounds are not organophosphates. One suggestion is to describe the metabolites as the oxo-butanamide SD 6167 and the hydroxy-butanamide SD 11733.

Page 26 of563. Underthe section "2.6.3 Evaluation ofMultiple Active Ingredients, Mixture, and Formulated Products" 2ndpp., EPA states, "However as these products contain bifenthrin, the effects on invertebrates are expected to be enhanced."

AMVAC's comment: The concentration ofbifenthrin in productmixes is generally low and its contribution to the overall toxicity to aquatic invertebrates is uncertain. Generally, pesticide mixtures act in an additive fashion (NAS, 2013; Rodney et al. 2013) thus there is little reason to believe toxicity wouldbe enhanced beyond what would be expected by an additive response.

4. Underthe section "2.6.4 Measures ofExposure" 2ndpp., EPA states, "EECs for dicrotophos include degradates ofdicrotophos in total toxic residues (TTR) approach. These residues include SD 6167, SD 11733, and SD228001."

AMV AC's comment: For a screening level assessment, this approach may be appropriate; however, for a refined assessment, a more accurate assessment would considerthe oxo-butanamide SD 6167 and the hydroxy-butanamide SD 11733, separately. Forthat reason, it would be appropriate to add an additional statement such as, "Becausethe 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.

5. In Table 1, page 4, EPA indicates thatreptiles and terrestrial phase amphibians are at risk as birds are used as a surrogate for these organisms. AMVAC's comment: In the absence oftoxicity data for terrestrial-phase amphibians and reptiles, it is standardpractice to use endpoints for avian species as a surrogate (EPA, 2008a). This extrapolation has little, ifany, empirical support. That is, the extrapolation is made out ofnecessity due to a paucity ofherptile toxicity data, notbecause ofscientific justification. Birds and herptiles belongto different taxonomic classes, and therefore, have different metabolic rates, diets, respiratory and reproductive systems and ecology in general. Many ofthese factors can be addressed using a more appropriate exposure model (T-HERPS) that can account for the lower metabolic rates and thus lower food and residue ingestion experienced by a herptile inthe field. 6. Underthe section "2.6.4 Measures ofExposure" 61h pp., EPA states, "Drinkingwater exposure alone was determined to be a potentialpathway ofconcern for avian and mammalian species on both an acute and chronic exposure basis".

Page 27 of56AMVAC's comment: As discussed in Section 2.3.4 ofthis 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 thatwouldresult in a significantly more realistic exposure scenario. AMV AC recommends thatthe Agency re-evaluate the use of SIP even atthe screening level, and conduct a more reasonable, realistic drinkingwater assessment for all pesticide products.

7. Underthe section "3.2.1.3 Monitoring Data" 1stpp., EPA states, "Itappears targeted monitoring was occurring at the site as 14 samples resulted in 14 detections between the days ofJune 21 and August 24 from 2005 to 2008. Sample frequency varied drastically though sampling occurred on consecutive days in some instances including the day following the peak detection of6.83 ppb. The subsequent concentration was 0.17 ppb. This rapid reduction in concentration indicates thatpeak concentrations are highly likely to be missed withouthigh frequency monitoring. NA WQA reports 65 detections from 99 samples in Mississippi indicating dicrotophos use areas are targeted among sampling sites. However, targeting monitoring around dicrotophos application and precipitation evens is not necessarily occurring andpeak detections may be missed."

AMV AC's comment: It is recognized thatthere is very limited background data concerningthe cause ofthe peak detection in water of6.83 ppb. As this value is significantly out ofrange ofotherreported values, it remains a distinctpossibilitythatthe finding represents some aberration as opposed to a true value. A more thorough assessment ofthe NAWQA data set is contained within AMVAC's response to EPA's assessment ofwater exposure and aggregate risk. 8. Under the section "3.2.1.3. Monitoring Data" 2nd pp., EPA states, "However, occurrence ofdicrotophos in groundwater may be expected since total toxic residues are mobile and persistentto hydrolysis and anaerobic metabolism."

AMVAC's comment: Soil dissipation studies do notprovide evidence ofresidues occurring at lower soil depths. Also, the EPA has demonstrated through PRZMJGW modeling thatthere is little exposure potential for dicrotophos within groundwater. 9. Under the section "3.2.1.5. Environmental Degradates" 1stpp., EPA states, "The major degradates resulting from the environmental degradation processes are SD 228001, SD 6167, and SD 11733 (table 3.4)."

Page 28 of56AMYAC's comment: Information concerning the identity ofthe 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 hydroxy-butanamide. 10. Underthe section "3.2.1.2 Aquatic Spray Drift Exposure to Dicrotophos" 1stpp., EPA states, "The use ofdriftreduction technology (DRT) could reduce the distance necessary for to prevent exceedances ofthe LOC but DRT is not currentlyrequired on dicrotophos labels. Also, "The default ASAE Fine to Medium droplet size distribution was assumed."

AMY AC's comment: AMY AC Chemical Corporation has labeling provisions that prescribes certain drift reductiontechnology (DRT) measures and would seek that the effect ofsuch mitigationbe incorporated into the risk assessment. Forexample, onthis basis, the default ASAE Fine to Medium droplet size distribution should be modified to a coarser droplet size. 11. Underthe section "3.3. Ecological Effects Characterization" 7thpp., EPA states, "The amount ofmonocrotophos that can form from dicrotophos and the rate offormation and decline in and/or on foliage soon after application is uncertain."

AMY AC's comment: Information concerningthe lowpotential for monocrotophos to be formed on foliage surface is evident based onthe foliar residue studytitled, "Dicrotophos and Monocrotophos in Dislodgeable FoliarResidues on Cotton Leaves" and filed under MRID 44731002. The study demonstrates that residues ofmonocrotophos on cotton foliage attwo distinct sites remained at very low levels over a 35 dayperiod after 3 applications. Onthis basis, the words, "in and/or onfoliage" shouldbe modified to "in foliage". 12. Under section "3.3 Ecological Effects Characterization", 5th pp., EPA states "Datathat pass the ECOTOX screen are evaluated along with the registrant-submitted data, and may be incorporated qualitatively or quantitatively into this endangered species assessment.
..." AMYAC's comment: EPA's PreliminaryEnvironmental Fate and Ecological Risk Assessmentfor the Registration ofDicrotophos (Case #145), is not an Endangered Species Assessment, butrather an ERAto evaluate the registration ofdicrotophos under FIFRA. 13. Underthe section "3.3.1 Aquatic ToxicityAssessment" table 3.11, EPA lists, "Acute/ Waterflea (Daphnia magna)/Length/21-dayNOAEC 

### = 0.0017 mg ai!L LOAEC 

### = 0.0028 mg ai/L".

AMY AC's comment: It is not clearwhether EPA intended to listthe NOEAC and LOEAC for reproductive effects, which are 0.0028 and 0.0044 mg ai/L, respectively. With respectto length measurements, the NOAEC and LOAEC are 0.00099 and 0.0017 mg ai/L, respectively. However, the length data do not indicate anytrend in effect versus concentration; thus we would conclude are not appropriate endpoints for consideration.

Page 29 of56Although according to the study author, underthe employed conditions ofstatistical testing, the vehicle control was determined to be significantly different from the top 3 dose levels, none ofthe doses demonstrated a reduction in length ofmore than 9%. An assessment ofmean mass provides no further clarity concerningthe length measurements as there were obvious problems with measurements ofthe control animals. It is our conclusionthatthe NOAEC and LOAEC associatedwiththe reproductionparameters should berelied upon for the chronic risk assessment as there is a clear dose response on otherparameters and the reproductionresults appearto be more reliable. 14. Under the section "3.3.1.2 Toxicityto Freshwater Invertebrates", "Chronic Effects" 1st pp, EPA states, "TheNOAEC andLOAEC were determined to be 0.0017 mg ai!L and 0.0028 mg ai/L based on reductions in mean total length"
AMV AC's comment: Per ourresponse in the previous comment, we proposethat the reproduction-basedNOAEC and LOAEC be utilized for risk assessmentpurposes. 15. Underthe section "3.3.2 Terrestrial Effects Characterization", "Chronic Effects" 7thpp, EPA states, "InAlabama, external and internal dicrotophos residues were detected on indigo buntings as high as 17 ppm and 0.51 ppm, respectively.
AMVAC's comment: Even for the individual avian species ofhighest residues, the measured internal dose level did not exceed the laboratory-based LD5

### oof3 mglkg/bw associated with the House sparrow (Passer domesticus), anotherpasserine species. There is no datato suggest that an external dose ofthis magnitude would have a detrimental effect on avian species. This data indicates that this exposure level would notplace this avian species at undue risk. Sample identification is contained within Table 7 ofthe report and indicates thatthe sample consisted ofskin and feathers. The efficiency oftransfer ofresidues associated withthe feathers onto the skin is likely nothigh and the range ofconcentration associated with samples having measured internal residues is consistentwith thatview. Inthe sample in question that had external residues of 17 ppm, the concentration ofresidues in the associated carcass was only 0.09 ppm. Therefore, there is no evidence that dicrotophos residues having toxicological implications occur athigh levels. 16. Underthe section "3.3.2 Terrestrial Effects Characterization", "Chronic Effects" 7thpp, EPA states, "While neither study design is sufficientlyrobust for quantitative use in risk estimation, anecdotal information contained within the studyreports is useful for risk characterization."

AMVAC's comment: We agree withthe statement only in thatthe avian effects due to the 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.

Page 30 of5617. Underthe section "3.3.2.2 Toxicity to Birds", "Acute and Sub-acute Effects", "Subacute', 2nd pp, EPA states, "Dicrotophos is classified as highly to toxic [Note typographical error with words "to toxic" inverted] veryhighly toxic to birds on a subacute dietary basis." AMV AC's comment: Although we do not dispute the EPA's classification on the basis ofthe laboratory studies, the extent ofexposure as evident in the two field studies even in view ofthe complications previously discussed, demonstrate thatthe chemical is not highlytoxic in the field where there were only limited mortalities noted. 18. Under the section 4.1.1.1. "Fish and Invertebrates", "Aquatic Invertebrates", 3dpp, EPA states, "the chronic LOC (1.0) is exceeded for freshwater and estuarine/marine invertebrates for all PRZM scenarios modeled (Table 4.4)."

AMVAC's comment: AMVAC believes thatthe chronic risk to aquatic organisms is best assessed by considering the extensive NA WQAmonitoring data set, which substantiates that actual exposure levels would be far lower than thatdetermined from modeling efforts. Therefore, although chronic risk as calculated using baseline PRZMIEXAMS modeling implies that there is some risk to aquatic organisms, realistic exposures in surface waters associated with agricultural areas as evidentby monitoring data is very low and would notpose a risk ofconcernto aquatic organisms. 19. Under the section 4.1.2.1. "Mammals", 1stpp, EPA states, "RQs exceed the acute nonlisted LOC (0.5) by a factor ofup to 23X (short grass)."

AMVAC's comment: Context shouldbeprovided onthe 23X exceedance factor as this maximum is as a result ofan exposure scenario that is unlikelyto occur in nature (i.e. a 20 g mammal consuming exclusively short grass). This information has been further refined within this document. 20. Underthe section4.1.2.1. "Mammals", 2ndpp, EPA states, "based onthe proposed maximum application rates on cotton, there are chronic dose-based exposure concerns for mammals ofall size classes for the short grass, tall grass, broadleafplant, fruits/pods, arthropods, and [Note typographical error "and and"] with granivore sub-classes. RQs exceed the LOC by a factor ofup to 915X (short grass)."

AMV AC's comment: This information has been further refined withinthis document. 21. Underthe section 4.1.2.2. "Birds", 2ndpp, EPA states, "RQs for acute dose-based exposure exceedthe acute non-listed species LOC (0.5) for all size classes and foraging groups by at least two fold and as much as 926X (small bird, short grass) (Table 4.9)."

Page 31 of56AMV AC's comment: This information has been further refined within this document. 22. Underthe section 4.1.2.2. "Birds", 3dpp, EPA states, "On a sub-acute basis. [Note typographical error as the periodpunctuation should be a comma] RQs for all size classes and foraging groups exceedthe acute non-listed species LOC (0.5) by at least two fold and as much as 32X."

AMV AC's comment: This information has been further refined within this document. 23. Under the section 4.1.2.2. "Birds", 4thpp, EPA states, "On a chronic basis. [Note typographical error as the periodpunctuation should be a comma] RQs for all size classes and foraging groups exceedthe chronic LOC (1.0) by at least 26X and as much as 422X (Table 4.11)."

AMV AC's comment: This information has been further refined within this document. 24. Under the section 4.2. "IncidentDatabase Review", 1stpp, EPA states, "Areview ofthe Ecological IncidentInformation System [Note typographical error- provide space between "Information" and "System"] (EllS) database for incidents involving dicrotophos was conducted on December 5, Fischer."

25. Underthe section 4.2. "Incident Database Review", 5thpp, EPA states, "Therefore, the weight ofthe evidence based on the currently available data suggests that direct effects to avian and mammalian species are expected from the currently registered use of dicrotophos."

AMVAC's comment: EPAhas cited incidents as late as 1976 and has suggested thatthe weight ofthe evidence forms a basis for assessing direct ecological effects from the current registered use. However, the current registered use differs from previous labels and agricultural practices in manyways. These exposure mitigation changes, some prescribed by EPA, have had a significant impact onreducing environmental concerns related to productuse. Further and most importantly, there is no evidence ofavian incidents associated withthe currentregistered use on cotton. 26. Underthe section 4.3.1. "Exposureto Aquatic Organisms", 1stpp, EPA states, "Environmental fate data were conservatively represented byusing the 90th percentile mean ofmetabolism half-life estimates."

AMV AC's comment: Our understanding is that EPA did notutilize the 90th percentile mean ofmetabolism half-life estimates as stated, but instead added conservatism to the assessment by incorporating a 3X multiplier to the single aerobic and anaerobic metabolism half-lives on file and a 6X factor to the aerobic aquatic metabolism half-life.

Page 32 of5627. Under the section 4.3.1. "Exposure to Aquatic Organisms", 1stpp, EPA states, "However, modelingvalues are onlytwo times larger than the highest reported monitoring value and higher monitoring values maybe found with more targeted monitoring approaches."

AMVAC's comment: We do not dispute the factual nature ofthe comment; however, the implications ofthe finding need to be more thoroughly examined. It is importantto consider that this single value is notrepresentative ofthe entire very large NA WQA dataset where residues are more than an order ofmagnitude lowerfor all other samples. A more thorough assessment ofthe NAWQA data set is contained within AMVAC's response to EPA's assessment ofwater exposure and aggregate risk.

28. Underthe section 4.3.1. "Exposure to Aquatic Organisms", 3dpp, EPA states, "Concentrations of0.6 ppb in water trigger the Endangered Species LOC (based on Daphnia magna toxicity endpoint of 12.7 ppb). This concentration is achieved at distances up to 331 feet from the edge ofthe field according to AgDrift v 2.1 for aerial applications.

AMVAC's comment: The spray drift assessment usingAgDriftv 2.01 is accurate for use practices that underlie the model when it was developed. Since the time when this data was developed, there have been important advances in reducing drift through implementation ofmore modem, 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 are significant instructions to reduce drift and we believe these have dramatically reduced drift. Therefore, the results ofAgDrift overestimate exposure and risk. Following is the extensive labeling instructions on our Bidrin label for reducing spray drift: "Spray DriftRequirements All aerial and ground application equipment must beproperlymaintained and calibrated using appropriate carriers. OBSERVE THE FOLLOWING PRECAUTIONS WHEN SPRAYINGIN THE VICINITY OF AQUATIC AREAS SUCHAS BUT NOT LIMITED TO LAKES; RESEVOIRS; RIVERS; PERMANENT STREAMS; MARSHES ORNATURAL PONDS; ESTUARIES AND COMMERCIAL FISHINGPONDS.

Page 33 of56Do not allow sprayto drift from the application site and contactpeople, structures people occupy at anytime and the associatedproperty, parks and recreational areas, non-target crops, aquatic and wetland areas, woodlands, pastures, rangelands, or animals. Do not apply by ground equipmentwithin 25 feet, or by airwithin 150 feet oflakes; reservoirs, rivers, permanent streams, marshes ornatural ponds, estuaries, and commercial fish ponds. For aerial applications, the sprayboom should be mounted on the aircraft so as to minimize drift causedbywingtip orrotor vortices. The minimum practical boom length should be used and mustnot exceed 75% ofwing span orrotor diameter. Droplet Size Use the largest droplet size consistentwith goodpest control. Formation ofvery small droplets maybe minimized by appropriate nozzle selection, by orientating nozzles away from the air stream as much as possible, and by avoiding excessive spray boom pressure. Spray should be released atthe lowest height consistent withpest control and flight safety. Applications more than 10 feet above the crop canopy should be avoided. WindDirection and Speed Make aerial or ground applications whenthe wind velocity favors on targetproduct deposition (approximately 3 to 10 mph). Do not apply hen wind velocity exceeds 15 mph. Avoid applications when wind gusts approach 15 mph. Wind speed mustbe measured adjacentto the application site on the upwind side immediatelypriorto application. Risk ofexposure to sensitive aquatic areas canbe reduced by avoiding applications when wind direction is towards the aquatic area. Do not cultivate within 10 feet ofan aquatic area so as to allow growth ofa vegetative filter strip. Lowhumidity and high temperatures increase the evaporationrate ofspray droplets and therefore the likelihood ofincreased spray driftto aquatic areas. Avoid spraying during conditions oflowhumidity and/or high temperature. Temperature Inversions Do not make aerial or ground applications into areas oftemperature inversions. Inversions are characterized by stable air and increasing temperatures withheight above the ground. Mist or fog may indicate the presence ofan inversion inhumid areas. Where permissible by local regulations the applicator may detect the presence ofan inversion by

Page 34 of56producing smoke and observing a smoke layer nearthe ground surface. In conditions of lowhumidity and high temperatures, applicators should use a coarser droplet size." 29. Underthe section 4.3.1.1. "Risks to Aquatic Animals", 2ndpp, EPA states, "the acute non-listed species LOC (0.5) for effects to freshwater invertebrates and acute restricted use LOC (0.1) for effects to estuarine/marine invertebrates are exceeded, withRQs as high as 1.33 and 0.22 for freshwater and estuarine species, respectively. Chronic risk LOCs (1.0) are also exceeded: RQs were determined to be as high as 7.2 and 3.97 for freshwater and estuarine invertebrates, respectively. "

AMV AC's comment: The exposure ofaquatic organisms is bestreflected bythe very large NA WQA dataset, which indicates that exposure levels in surface water should not be detrimental to aquatic species. The EPA's PRZM/GW modeling assessment is sufficientto demonstrate that exposure associated with groundwater sources would not pose a risk to aquatic organisms. 30. Underthe section 4.3.2. "Exposure to Terrestrial Organisms", 1stpp, EPA states, "The spray drift model AgDriftprovides helpful bounds which define the spatial extent ofrisk concern resulting from off-field drift at currentlyregistered dicrotophos application rates."

AMV AC's comment: AMV AC proposes thatthe Agency's statementbe further clarified by adding information that explains that the AgDriftmodel is based on a dataset that reflects application practices that have since been refined and are included on current product labels; therefore the modeling outputs likely exaggerate actual driftconcerns; but provide a useful screening level assessment. 31. Underthe section 4.3.2.1. "Risks to Mammals", "Cotton Use Pattern", 1stpp, EPA states, "Acute upperbound Kenega RQs derived for mammals in the RiskEstimation section of this assessment indicate acute listed mammalian riskLOC (0.1) exceedances for alllOOO gram granivore mammals (RQ = 0.07). Based onthe EEC values from T-REX and the LD50 from the available acute rat study, the highest RQ value for 15 gram mammals foraging on short grass -the most sensitive size class and forage item combination- is 11.44.

AMV AC's comment: This information has been further refined within this document. 32. Underthe section 4.3.2.1. "Risks to Mammals", "Cotton Use Pattern", 2ndpp, EPA states, "Dose-based and dietary based chronic RQs exceed the LOC (1.0) for all forager types. Dose-based chronic RQs range from 5.82 to 915, and the dietary based chronic RQs range from 6.59 to 105. The exceedances for dicrotophos are greater than 915-fold (dose-based) and 100-fold (dietary based) for short grass mammalian foragers. These exceedances are based on reduced pup survival observed in a three-generation rat
Page 35 of56reproduction study. Since terrestrial application residues exceed 2 mg ai/kg dietary item (i.e., the mammalianreproductionNOAEC) for at least 105 days (fruits/pods/seeds) and as many as 250 days (short grass) following the first application ofdicrotophos, there is a high degree ofconfidence in the prediction ofadverse chronic effects.

AMY AC's comment: This information has been further refined within this document. As this assessment addresses reproductive issues that are indicative ofpopulation-based effects, it is worthier noting that the baseline risk assessment itselfis derived from the risk to the most sensitive individual ofa group ofanimals. The use ofthe NOAEC is not population-based as the impact ofa small portion ofanimals is unlikelyto cause a detrimental effectto the population as a whole. Therefore, we find that EPA's statement that it believes thatthere is a high level ofconfidence intheir prediction ofadverse chronic effects is overstated. A more appropriate statementwouldhave been thatbased onthe Agency's risk assessment, it finds that chronic RQs exceedthe regulatory standards. 33. Underthe section 4.3.2.1. "Risks to Mammals", "Cotton Use Pattern", 3dpp, EPA states, "EECs exceed the mammalian acute non-listed species LOC (0.5) for 164 days after application for short grass, assuming a 35-dayhalf-life and two applications of0.5 lb ai/A applied at a 14-day interval (Figure 4.1). With the same model inputparameters, EECs exceedthe mammalian acute non-listed species LOC for 116 to 134 days following application for all other forage types except fruits/pods/seeds, where the mammalian acute non-listed species LOC is exceeded by23 days following the first application."
AMYAC's comment: This information has been further refined within this document. 34. Under the section 4.3.2.1. "Risks to Mammals", "CottonUse Pattern", 5thpp, EPA states, "To spatially examine the potential risk ofspray drift, simulations were performed with the program AgDRIFT. It was determined that spray drift EECs yield acute dosebased RQs that exceedthe acute listed species LOC (0.1) for short grass even atthe model limit (997 feet from the treated field). However, spray drift is not ofacute dosebasedrisk concern for listed granivore mammals. Ag DRIFT also indicates that spray drift EECs yield chronic dietary RQs that exceed the LOC (1.0) for short grass even at the model limit (997 feet from treated field). Even consideringthe least conservative forage class (fruits/pods). [Note typographical error as the periodpunctuation should be a comma] RQs resulting from spray drift EECs would exceed the chronic LOC at least as far as 650 feet from the treated field." AMY AC's comment: as previously stated, the spray drift assessment using AgDrift v 2.01 is accurate for use practices thatunderlie the model. Since the time whenthis data

Page 36 of56was developed, there have been important advances in reducing driftthrough implementation ofmore modem, 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 thatprevious concerns relating to chemical drift have been properly mitigated. 35. Underthe section 4.3.2.2. "Risks to Birds", "CottonUse Pattern", 2ndpp, EPA states, "Similarto the mammalian chronic EECs, acute avian EECs are calculated on both a dietary and dose basis. Forthe cotton use, acute dose-based upperbound KenagaRQs exceed the acute non-listed species LOC (0.5) for all size classes and foraging groups. Sub-acute dietary and chronic dietary upperbound Kenaga RQs exceedthe acute nonlisted species LOC (0.5) and chronic LOC (1.0), respectively, for all forager group types. Considering the magnitude ofacute non-listed species LOC exceedances, as much as 926-fold, there is a high degree ofcertaintythat avian species will be adversely affected by dicrotophos applied to cotton."
AMVAC's comment: This information has been further refined withinthis document. Also, it is not clearwhatthe Agency means when it states thatthere is a high degree of certainty that avian species will be adversely impacted by dicrotophos. As stated earlier, the chronic risk assessment is more gearedtowards assessing the impact on individual birds, rather than onthe species due to the use ofthe NOAEC as the toxicological endpoint. Also, we believe thatthe Agency is overstating its conclusionbased on a deterministic, screening level assessmentwithout fully examiningthe supporting evidence (incidentreports and field studies)

.. 36. Underthe section 4.3.2.2. "Risks to Birds", "CottonUse Pattern", 3dpp, EPA states, "EECs exceed both the avian acute listed species LOC (0.1) and the avian chronic LOC (1.0) for 270 days and 320 days, respectively, after first application for short grass, assuming a 35-day half-life and two applications of0.5 lb ai/A applied at a 14-day interval (Figure 4.2). With the same model inputparameter, EECs exceedthe avian acute non-listed species LOC (0.5) for 140 and 160 days following application for all other forage types except fruits/pods/seeds, where the avian acute non-listed species LOC is no longer exceeded after day 48. Sinceterrestrial application residues exceed 0.5 mg ailkg dietary item (i.e., the avian reproductionNOAEC) for more than 267 days following the first application ofdicrotophos for all forager types except consumers offruits/nuts/seeds (dicrotophos residues above the NOAEC through day 180), there is a high degree of confidence in the prediction ofadverse chronic effects. Even under the less conservative T-REX exposure scenario, mean Kenaga acute and chronic RQs exceedthe acute listed species or chronic LOC for all size classes and forage types.

AMV AC's comment: This information has been further refined within this document.

Page 37 of56Also, it is importantto place into perspective the timing calculated for achieving an acceptable LOC as the shape and slope ofthe curves have a significantbasis on how far the acceptable values extend and relatively small overages inthe RQ values may occur well before the calculated times associated with these values. This is evidentfor assessing the effect oftime on achieving an acceptable chronic LOC in EPA'sFigure 4.2 Avian LOCs Superimposed onResidue Decline Curve. Itis also importantto note that the residue decline curves represent generic upperbound estimates that likely underestimate the rate ofresidue degradation on food items. It is also worth noting that to properly assess a sophisticated approach for evaluatingthe meaning ofthe time periods associated withRQ exceedances, it is important to considerthe likely exposureperiods ofdifferent species ofbirds. 37. Underthe section4.3.2.2. "Risks to Birds", "Cotton Use Pattern", 4thpp, EPA states, "To spatially examine the potential risk ofspray drift, simulations were performed with the spray drift modelingprogram AgDRIFT. It was determined that spray drift EECs yield acute dose-based RQs that exceedthe acute listed species LOC (0.1) or short grass even atthe model limit (997 feet from the treated fields). [Note typographical error with unnecessary period] and for all other forage classes at least 730 feet from the treated field. Spray drift EECs yield subacute dietary RQs that exceed the acute listed species LOC (0.1) for short grass even at the model limit (997 feet from the treated field). [Note typographical error with unnecessaryperiod] and for all otherforage classes at least 108 feet from the treated field. Spray drift EECs yield chronic dietary RQs that exceedthe LOC (1.0) for short grass even at the model limit (997 feet from the treated field). [Note typographical error with unnecessaryperiod] and for all other forage classes at least 250 feet from the treated field." AMV AC's comment: As previously stated, the use ofAgDRIFT is appropriate for a screening level assessment; however, with the implementation ofmore modem good agricultural practices, appropriate labelingprovisions have been developed for dicrotophos products that address these previous concerns relating to drift associated with outdated application procedures. AMVAC believes that current labelingpractices relating to drift fully address environmental exposure issues. 38. Underthe section 4.3.2.2. "Risks to Birds", "CottonUse Pattern", 5thpp, EPA states, "The STIRmodel output indicates that inhalation maybe an exposure routes ofconcern for avian species. Consideringthatthe available acute mammalian inhalation toxicity study used a supersaturated solution and recorded no mortalities, and the exposure to droplets in the field wouldbe expectedto be ofa lesser duration (i.e., less than four hours). [Note typographical error with as period should be a comma] inhalation is not regarded as the primaryroute ofexposure eliciting observed avian toxicological response.

Page 38 of56AMV AC's comment: AMV AC agrees with the EPA's statementthat inhalation should not be regarded as a primaryroute ofexposure. We also believe that in consideration of all ofthe 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 ofexposure concern. 39. Underthe section 4.4.2. "Effects", 3dpp, EPA states, "An acceptable foliar residue toxicity study with honey bees (OCSPP 850.3030) would allow for determination ofa 24- h TR25 . This data would reduce uncertainties surrounding the length oftime postapplication that residues ofdicrotophos on foliage are toxic to honeybees."

AMV AC's comment: AMV AC believes that althoughthere is always some value for developing additional information, there is already sufficient evidence that dicrotophos use on cotton does not yield environmental incidents on honeybees nor is there data to indicate any exposure. The Bidrin label also calls for care in terms ofnot utilizingthe product whenbees are detected in the fields designated for treatment. Also, consideration ofdislodgeable foliar residue data on cotton as previously described in this document provides evidence to support the contention that dicrotophos residues are notpersistent on foliage.
40. Underthe section 4.4.2. "Effects", 3dpp, EPA states, "A chronic fish study with an estuarine/marine species exposedto dicrotophos is not available. While it is uncertain whether estuarine/marine species maybe more sensitive to dicrotophos exposure of chronic duration than freshwater species, available data indicate thatestuarine/marine species are nearly 14 fold less sensitive to dicrotophos exposure ofacute duration than freshwater fish species exposed."

AMVAC's comment: As EPA has determined that the acute risk to freshwater and estuarine/marine fish is not ofconcern and that the chronic risk quotients for freshwater fish are all less than 0.001, the development ofadditional chronic data for the refinement ofrisk to estuarine/marine species is notwarranted. 41. Under the section 5. "Endocrine Disrupting Screening Program", 3dpp, EPA states, "Dicrotophos is onList 2. List 2 represents the next set ofchemicals for which EPA intends to issue test orders/data call-ins in the near future. Section 6. "FederallyThreatened and Endangered (Listed) Species Concerns". AMVAC's comment: AMVAC recognizes the currentvariability in the approach and proposed methods for the conduct ofNationalEndangered Species Assessments for pesticide products. In 2012, the Services and EPA asked the National Academy of Sciences (NAS) to address several areas ofconcern with regard to howpesticide risk

Page 39 of56assessments are conducted by EPA andthe 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 FIFRAwith direct consideration ofthe ESA Section 7 requirement (Figure 1). In addition, the NAS panel recommended the use ofrefined approaches (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 ofthe process relates to the use ofendangered species LOCs (Section 6.2- 3rdpp). The NAS reportrecommended strongly againstthe use ofLOCs, favoring probabilistic approaches (NAS, 2013). The Agency and Services initiallyresponded with a recommendation ofuse ofa one-in-a-million analysis as described in the Interim Approach. Thus, use ofendangered species LOCs is unlikely in theprocess at this time. Recognizing the on-going uncertainty in the ESAprocess for pesticides, Intrinsik and AMV AC will monitorprogress in this area and will provide appropriate input as required to support dicrotophos. 42. Appendix D- Appendix D contains the STIRmodel pages used by EPA in the assessment. AMVAC's comment: The Agency was not consistent in the application ofthe Mineau scaling factor for dicrotophos of 1.118 for birds in this analysis, butused 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 40 of565.0 REFERENCES Best, L.B., R.C. Whitmore and G.MBooth. 1990. Use ofcornfields bybirds during the breeding season: The importance ofedge habitat. Am. Midl. Nat. 123:84-99 Best, L.B., D.F. Freedmark, J.J. Dinsmore and M. Camp. 1995. A review and synthesis ofhabitat use bybreedingbirds in agricultural landscapes oflowa. Am. Midl. Nat 134:1-29. Bokkers, B.G.H. and W. Slob. 2007. Deriving a data-based interspecies assessment factor using the NOAEL and the benchmark dose approach. Critical Reviews in Toxicology 37(5):355-373. Brain, R.A., R. S. Teed, J. Bang, P. Thorbek, JeffPerine, N. Peranginangin, M. Kim, T. Valenti, W. Chen, R. L. Breton, S. I. Rodney, and D. 

### R.I. Moore. 2014. RiskAssessment Considerations With Regard to the Potential Impacts ofPesticides on Endangered Species. IEAM October 2014. Chappell, W.R. 2002. Scalingtoxicity data across species. Environmental Geochemistry and Health 14(3):71-80. Davidson, I.W.F., J.C. Parker, R.P Beliles. 1986. Biological basis for extrapolation across mammalian species. Regulatory Toxicology and Pharamacology 6:211-237. Doyle, R.L. and J.R. Elsea 1963. Toxicity Studies on Bidrin in Geese. Hill Top Research Institute, Inc. Miamiville, OH. December 11, 1963. [MRID 00013439]. ECOFRAM (Ecological Committee onFIFRA RiskAssessmentMethods). 1999. ECOFRAM Terrestrial DraftReport. May 10, 1999. http://www.epa.gov/oppefedl/ecorisklterrreport.pdf AccessedNovember, 2014. EPA (US Environmental Protection Agency). 1998a. Health Effects Test Guidelines. OPPTS 870.3800. Reproduction and FertilityEffects. EPA 712-C-98-208. August 1998. EPA (US Environmental Protection Agency). 1998b. Health Effects Test Guidelines. OPPTS 870.4100. Chronic Toxicity. EPA 712-C-98-210. August 1998. EPA (US Environmental ProtectionAgency). 1993. Wildlife Exposure Factors Handbook Volume I ofii. Office ofResearch and Development, Washington D.C. EPA/600/R-93/187a. EPA (US Environmental ProtectionAgency). 2004a. Interim Guidance ofthe Evaluation Criteria for Ecological Toxicity Data in the Open Literature. Phase I and II. Procedures for Identifying, Selecting, and Acquiring ToxicityDataPublished inthe Open Literature. Office ofPesticide Programs. July 16, 2004. EPA (US Environmental ProtectionAgency). 2004b. Overview ofthe Ecological Risk Assessment Process in the Office ofPesticide Programs, U.S. Environmental ProtectionAgency. Endangered and Threatened Species Effects Determinations. Office ofPrevention, Pesticides and Toxic Substances, Office ofPesticidePrograms, Washington, D.C. January 23, 2004.

Page 41 of56EPA (US Environmental Protection Agency). 2005. General instructions for using AGDISP (v.8.13) to determine distance offfield needed to be below the LOC (to estimate terrestrial action area for endangered species/to develop potential mitigation measures-buffers. Internal EPA draft guidance, Environmental Fate and Effects Division, dated October 2005. EPA (US Environmental ProtectionAgency). 2007. Risk ofAldicarb Use to Federally Listed Endangered CaliforniaRed Legged Frog 

### (Rana aurora draytonii). Environmental Fate and Effects Division, Office ofPesticide Programs, Washington, DC. July 17, 2007. EPA (US Environmental Protection Agency). 2008. Risk ofOxy:fluorfen Use to Federally Threatened CaliforniaRed Legged Frog 

### (Rana aurora draytonii): Pesticide Effects Determination. Environmental Fate and Effects Division. Office ofPesticide Programs. Washington, DC. October 16, 2008. EPA (US Environmental Protection Agency). 2008. Risks ofDimethoate Use to the FederallyListed CaliforniaRedLegged Frog 

### (Rana aurora draytonii). Pesticide Effects Determination. Environmental Fate and Effects Division Office ofPesticide Programs Washington, D.C. 20460 January 31, 2008. EPA (US Environmental Protection Agency). 2009a. Risk ofDicofol Use to FederallyListed Endangered CaliforniaRed Legged Frog 

### (Rana aurora draytonii): Pesticide Effects Determination. Environmental Fate and Effects Division. Office ofPesticide Programs. Washington, DC. June 15, 2009. EPA (US Environmental Protection Agency). 2009b. Risk ofEndosulfanUse to Federally Threatened CaliforniaRed-legged Frog 

### (Rana aurora draytonii), Bay CheckerspotButterfly 

### (Euphydryas editha bayensis), Valley Elderberry Longhorn Beetle 

### (Desmocerus californicus dimorphus), and CaliforniaTiger Salamander 

### (Ambystoma californiense) And the Federally Endangered San Francisco Garter Snake 

### (Thamnophis sirtalis tetrataenia), San Joaquin Kit Fox 

### (Vulpes macrotis mutica), and SaltMarshHarvest Mouse 

### (Reithrodontomys raviventris): Pesticide Effects Determinations. Environmental Fate and Effects Division. Office ofPesticide Programs. Washington, DC. June 18, 2009. EPA (US Environmental ProtectionAgency). 2009c. Risk ofOxamyl Use to Federally Threatened CaliforniaRed Legged Frog 

### (Rana aurora draytonii): Pesticide Effects Determination. Environmental Fate and Effects Division. Office ofPesticide Programs. Washington. EPA (US Environmental Protection Agency). 2009d. Risks ofTrifluralinUse to the Federally Listed California Red-legged Frog 

### (Rana aurora draytonii), Delta Smelt 

### (Hypomesus transpacifzcus), SanFrancisco Garter Snake 

### (Thamnophis sirtalis tetrataenia), and San Joaquin KitFox 

### (Vulpes macrotis mutica): Pesticide Effects Determination. Environmental Fate and Effects Division. Office ofPesticide Programs. Washington, DC. October 16, 2009.

Page 42 of56EPA (US Environmental Protection Agency). 2010. User's Guide Screening Imbibition Program (SIP) Version 1.0. http://www.epa.gov/oppefedl!models/terrestriallsip/sip user guide.html EPA (US Environmental Protection Agency). 2011a. Evaluation Guidelines for Ecological ToxicityData in the Open Literature: Procedures for Screening, Reviewing, and UsingPublished Open Literature Toxicity Data in Ecological RiskAssessments. Office ofPesticide Programs. May 9, 2011. EPA (US Environmental ProtectionAgency). 2011b. Recommended Use ofBodyWeight as the DefaultMethod in Derivation ofthe Oral Reference Dose. Office ofthe Science AdvisorRisk AssessmentForum. U.S. Environmental ProtectionAgency. Washington, DC 20460. 201 L EPA (US Environmental ProtectionAgency). 2012. Risks ofMalathion Use to the Federally ThreatenedDelta Smelt (Hypomesus transpacificus) and California Tiger Salamander (Arnbystoma califomiense), Central California DistinctPopulation Segment, andthe Federally Endangered California Tiger Salamander, SantaBarbara County and Sonoma County Distinct Population Segments. Pesticide Effects Determinations PC Code: 057701 CAS Number: 121-75- 5 Environmental Fate andEffects Division Office ofPesticide Programs Washington, D.C. 20460 September 29, 2010. EPA (US Environmental ProtectionAgency). 2012a. User's Guide T-REX Version 1.5.2 (Terrestrial Residue EXposure model). Accessed August 2013 from http:/ /www.epa.gov/oppefedllmodels/terrestrialltrex/t rex user guide.htm. EPA (US Environmental ProtectionAgency). 2012b. Ecological Effects Test Guidelines. OCSPP 850.2300: Avian Reproduction Test. EPA 712-C-023. January 2012. EPA (US Environmental ProtectionAgency). 2014. PreliminaryEnvironmental Fate and Ecological Risk Assessmentfor the Registration ofDicrotophos. US Environmental Protection Agency, Washington, DC. July 10, 2014. Fleming, W.J. and S.P. Bradbury. 1981. Recovery ofcholinesterase activity in mallard ducklings administered organophosphorus pesticides. Journal ofToxicology and Environmental Health 8.5-6:885-897. Fleming, W.J., and C.E. Grue. 1981. Recovery ofcholinesterase activity in five avian species exposedto dicrotophos, an organophosphorus pesticide. Pesticide Biochemistry and Physiology 16:129-135. FlemingW.J. 1981. Recovery ofbrain and plasmacholinesterase activities in ducklings exposed to organophosphorous pesticides. Arch. Environ. Contam. ToxicoL 10(2):215-29. Fletcher, J.S., 

### I.E. Nellessen and T.G. Pfleeger. 1994. Literature review and evaluation ofthe EPA food-chain (Kenega) nomogram, an instrument for estimatingpesticide residues onplants. Environ Toxicol Chern 13(9):1383-1391.
Page 43 of56Flickinger, E.L., D.H. White, C.A. Mitchell, T.G. Lamont. 1984. Monocrotophos and dirotophos residues in birds as a result ofmisuse oforganophosphates in Matagorda County, Texas. National Library ofMedicine. Journal- Association ofOfficial Analytical Chemists 67.4: 827- 828 Grue, C.E, Shipley, B.K. (1984) Sensitivity ofnestling and adult starlings to dicrotophos, an organophosphatepesticide. Environ. Res. 35, 454-465 Hill, E.F. (1993) "Acute and subacute toxicology in evaluation ofpesticide hazard to avian wildlife" Up and Down Procedure Peer Panel Report; Appendix P-3 http:1 /ntp.niehs.nih.gov /iccvam/docs/acutetox docs/udpproc/udpfinO1Iappend/appp3.pdf Hoerger, F. andE. E. Kenaga. 1972. Pesticide residues onplants: Correlation ofrepresentative data as a basis for estimation oftheir magnitude in the environment, pp. 9-28. In: Coulston, F. and F. Korte (Eds.) Environmental Quality and Safety: Chemistry, Toxicology and Technology. George Thieme Publ, Stuttgart, West Germany. [MRID 47299308]. Knapper, L.D., G.K. Smith, C.A. Ollson and M. Stephenson. 2009. Use ofBodyMass Scaling of Dose in Ecological Risk Assessments. In: EcotoxicologyResearch Developments, Santos, E.B. (ed). NovaPublishers NJ. Leggett, M. Memo to OPP Docket. Environmental ProtectionAgencyDocket Centre, Washington, DC. April25, 2014. Re: Docket ID No. EPA-HQ-OPP-2013-0676-0025. Pesticides; Consideration ofSpray Drift inPesticide Risk Assessment: Notice ofAvailability and Request for Comment 79 FR4691. January 29, 2014 Mineau, P., B.T. Collins and A. Baril. 1996. Onthe use ofscaling factors to improve interspecies extrapolation ofacute toxicity in birds. Regul. Toxicol. Pharm. 24: 24-29. Mitchell, C.A., D.H. White, E.J. Kolbe, R.C. Biever. 1984. Dicrotophos poisoning ofGreattailed Grackles in Texas. Journal ofWildlife Diseases. 20(3):256-257. Nagy, K.A. 1987. Field metabolic rate and food requirement scaling in mammals and birds. Ecol Monogr 57: 11-128. Nagy, K. and C. Peterson. 1988. Scaling ofWater Flux Rate in Animals. University ofCalifornia Press, Berkeley, CA. Nagy, K.A., LA. Girard, and T.K. Brown. 1999. Energetics offree-ranging mammals, reptiles and birds. Annu Rev Nutr 19: 247-277. NAS (National Academy ofSciences). 2013. Assessing Risks to Endangered and Threatened Species from Pesticides. National Academy ofSciences. TheNational Academic Press, Washington, DC.

Page 44 of56Palmer, D.A., H. Krueger, and M. Jaber. 1988. An evaluation ofits effects upon wildlife on and around cotton fields in southwestern Arizona. MRID 40873701 Prochaska, L.M. 1998. Dissipation ofdicrotophos dislodgeable foliar residues on cotton treated with Bidrin 8®. Phase 1- Field Investigation. Phase 2- Analytical. Sponsor AMVAC Chemical Corporation. 4100 EastWashington Blvd., Los Angeles, California. 90023. Rodney, S.I., R.S. Teed and D.R.J. Moore. 2013. Determination ofHazardous Concentrations with Species SensitivityDistributions. Version 3, April, 2013. Unpublished study performed by Intrinsik Environmental Sciences, Ottawa, ON, for: Canadian Council ofMinisters ofthe Environment. Sample, B.E., D.M. Opresko and G.W. Suter II. 1996. Toxicological Benchmarks for Wildlife: 1996 Revision. Prepared for the US Department ofEnergy. ES/ER/TM-86/R3. Sample, B.E. and C.A. Arenal. 1999. Allometric models for interspecies extrapolation ofwildlife toxicity data. Bulletin ofEnvironmental Contamination & Toxicology 62:653-663. Sheeley, D., J.D. Dingledine, H. Kueger, D.A. Palmer, and M. Jaber. 1987. Dicrotophos: An evaluation ofits effects upon wildlife on and around cotton fields in southeastern Alabama. [MRID 40917001]. Sullivan, J.P. andJ.D. Wisk. 2012. Usingthe Terrestrial Residue Exposure (T-REX) model to assess threatened and endangered bird exposure to and risk from pesticides. IEAM 9(3): 480- 495. Travis, C.C. and R.K .White. 1988. Interspecific scaling oftoxicity data. Risk Analysis 8:119- 125.

Page 45 of56

# APPENDIXA Refined Deterministic TotalDaily Intake Models for Birds and Mammals thatFrequent Cotton Fields.

Page 46 of56The bird and mammal assessment conducted bythe Agency in the dicrotophos preliminary ERA (EPA, 2014) used T-REX as the modeling line ofevidence to characterize risk. As mentioned in the response document, there are numerous issues with the approach that T-REX used to estimate total daily intake from an oral or dietary perspective. A more accurate methodto determine risk is with the free metabolic rate (FMR) approach where the energy orthe diet is taken into account rather than simply dietary mass. In addition, modelingwith a more realistic estimate ofthe foliar degradation rate than the default 35 d value used bythe EPA in T-REX. The analyses do not include consideration oftime spent foraging in the field, and other factors that would significantlyreduce exposure. However, the results demonstrate thatriskto birds and mammals are overstated in the EPA preliminaryrisk assessment (EPA, 2014). Short species descriptions are provided below, followed bythe calculations for the refined deterministic total daily intake model and results. Birds Northern cardinal The Northern cardinal (Cardinalis cardinalis), order Passeriformes, is found throughout the eastern United States and Mexico as well as in southern Ontario (Robbins, 1991; Rosenberg et al., 1991). Habitat is varied and may include forest edges, shrubby areas, hedgerows in agricultural fields, and grasslands (Dow, 1969; Em1en, 1972). Northern cardinals feed on soil surface invertebrates (29%), seeds (45%), fruits (24%), and some broadleafforage (2%). The meanbody weight ofadult birds is 44 g (Laskey, 1944). Indigo bunting The Indigo bunting (Passerina cyanea), order Passeriformes, is a small migratory songbirdthat breeds in eastern North America and the southwesternUnited States. The Indigo bunting is a frequently observedbird species in agricultural areas inthe United States (Conover et al., 2014). Duringthe breeding seasonthese birds will forage onthe ground or in trees or shrubs for small seeds (22%) and terrestrial arthropods (12% soil surface invertebrates; 66% foliagedwelling invertebrates). The meanbody weight for adult Indigo buntings is 14.5 g (Dunning, 1993).

Page 47 of56American wigeon The American wigeon (Anas americana), order Anseriformes, is an abundant duckthatbreeds in northwestern North America. It is a dabbling duck, but is known to commonly leave water and graze on vegetation in agricultural fields. Its diet consists ofsmall seeds (41%), grasses (18%), and broadleafforage (41%). The meanbodyweight for the American wigeon is 756 g (standard deviation of79.9 g) (Giesy and Solomon, 2014). 

### Mammals Meadow vole The meadow vole (Microtuspennsylvanicus) is found throughout North America inmeadows, lowland fields, grassy marshes, and along rivers and lakes (Reich, 1981; Zimmerman, 1965; Getz, 1985; Neuburger, 1999). This species commonly inhabits agricultural areas including pastures, hay and grain fields (Johnson andJohnson, 1982; Burt and Grossenheider, 1980). The meadow vole is active both day and night with a small home range of<0.1 ha (<1000 m2) (Boonstra and Rodd, 1983; Elbroch and Murie, 1963; Banfield, 1974; Neuburger, 1999). The average adult body weight ofthe meadow vole during the agricultural growing season is 33.8 g (based on data collected in Boonstra and Rodd (1983) and Brochu et al. (1998)). Itfeeds mainly on herbaceous matter (averagingby volume 55% dicot shoots, 32% monocot shoots, 4.5% seeds, 1.3% roots), with some consumption offungi (5.8%) and insects (1.8%) (Lindroch and Batzli, 1984). White-Tailed Deer White-tailed deer (Odocoileus virginianus) was selected as a focal species because they are large, browsing ruminants (i.e., herbivores) and they are the most widely distributed North American mammal (CWS, 1990). Duringthe growing season, white-tailed deer consume primarily monocot and dicot shoots and leaves, which are likely to have relatively high amount ofpesticide residues on fields immediately following pesticide application. They can survive in a variety ofhabitats. Ideal conditions provide a combination ofdense forest and edge environments (Dewey, 2003). The diet ofwhite-tailed deer varies seasonally withthe availability offood items. This assessment focused on dietary items ofthe growing season. Inthe spring and early summer, deer primarily consume leaves, forbs and grasses (Short, 1986; Daigle et al., 2004). When present, food crops can make up an important part ofthe diet (Daigle et al., 2004). In late summer, fruits become a significant food source. A study performed in Quebec determined the body weights ofmale and female white-tailed deer for different age groups inthree separate populations (Lesage et al., 2001). The

Page 48 of56populations were differentiated by their density and according to various climatic conditions. Body weights for adult male white-tailed deer (:2: 2.5 years) ranged from 53 to 116 kg adult female (:2: 2.5 years) body weights ranged from 39 to 52 kg. Forthe exposure analysis, the mean weight offemales was estimated to be 45 kg (SARA, 2006).

Page 49 of56Example Calculations for Meadow vole The table below provides information on the sample calculations used to derive the total daily intake (mg ai/kg bw) for the Meadowvole. The same approach was applied to all ofthe cotton specific surrogate species, withthe models appropriately parameterized for those species. The mass ofdicrotophos associated withthe actual meadow vole diet was calculated directly in T-REX vl.5.1 assuming a the following use pattern parameters (0.50 lb ai/A, 2 applications, and 14 day interval). The default 35 day foliar DT50. Parameter Equation Reference I Information Exposure

= 2.514*(body weight (g))0507 Mammalian rodent equation

- EPA Field metabolic rate (FMR) = 2.514*(33.8 g)0 507 1993 (kcal/day) Body weight

- Boonstraand Rodd = 14.98 (1983); Brochu eta!. (1998) EPA, 1993 GE- gross energy (kcal/g) values 0.63 kcal/g ww (leaves)" 1.3 kcal/g ww (young grasses) 4.6 kcal/g ww (seeds) 0.71 kcal/g ww (roots)b 1.6 kcal/g ww (average ofgrasshoppers, FMR crickets and beetles) IP=l[(GEj•AEj)*Pil AE

- assimilation efficiencyproportion Mass ofprey consumedper day = 14.98 "'""[0.55*(0.63*0.73) + 0.73 (green forbs- rabbits, voles, (g/day) 0.32*(1.3*0.73) + 0.045*(4.6*0.85) + mice)b 0.013*(0.71*0.73) + 0.058*(0.63*0.73) + 0.85 (seeds, nuts- voles, mice) 0.018*(1.6*0.87)] 0.87 (insects- small mammals) = 18.94 p -proportion ofdiet by mass 0.55 (dicot shoots) 0.32 (monocot shoots) 0.045 (seeds) 0.013 (roots) 0.058 (fungi) O.Ql8 (insects) Mass ofdicrotophos assuming a diet comprised of55% dicots (tall grass), EPA, 2012 (T-REX v1.5.2) 32%monocots (short grass), 4.5% = 96.68 (tall grass) (2 applications of0.5 lb/A, using 14- seeds (fruits/ pods/ seeds), 1.3%roots = 210.94 (short grass) day application interval and 35-day (broadleafplants), 5.8% fungi = 13.18 (fruits/ pods/ seeds) foliar degradation rate) (broadleafplants), and 1.8% insects = 118.86 (broadleafplants)a (arthropods) = 82.62 (arthropods) ww- wet weight (upper bound T-REXresidue values) (mglkg ww)
= Mass ofprey consumed per day (

### ...L) * day l:P[Mass ofdicrotophosi (**~)** *Pi] * kgww**0.001~** g Mass ofdicrotophos in daily diet = 18.94 g/day*(0.55*118.86 mg/kg ww+ (mg/day) 0.32*210.9 mg/kg ww+ 0.045*13.18 mg/kg ww+ 0.013*118.86 mg/kg ww+ 0.058*118.86 mg/kg ww+ 0.018*82.62 mg/kg ww)*0.001 kg/g =2.7 Daily dose for meadowvole = 3.2 mg/kg bw/day-<-- 0.0338 kg (mg/kg bw/day) =80.3

Page 50 of56Parameter Equation Reference I Information Exposure Effects RatLD50 for dicrotophos (acute) 8 (female) Acute mammal single dose oral LD50 selected by EPA (Ace. Nos. 261098 & (mg/kg bw) 11 (male) 43893901) Female:

= 8*(350 g +- 33.8 g) 0• 25 RatLD50 scaledto meadowvole body = 14.35 EPA, 2012 (T-REX v1.5.2) weight (acute) (mg/kg bw) Male:

= 11 *(350 g +- 33.8 g) 0• 25

= 19.73 ' The gross energy ofdtcot leaves was used as a surrogate for fungt m the absence ofavatlable data for thts feed ttem. b The gross energy for roots was calculated using the percentmoisture for leaves. ' Fungi and roots were assumed to have the same AE distribution and residue values as monocot and dicot leaves because no data were available

for these items.
Acute The RQs for acute exposure ofthe meadow vole to dicrotophos are: RQ(jemales) = mg 80.3 kjibw mg 14.35 kg bw 5.6

mg 80.3 kg bw RQ(males) = mg = 4.1 19.7 kg bw

Page 51 of56Table A-1 Avian Total Daily Intake Modeling Results T-REXShort Fieldmetabolic Massofprey Mass of GrassRQ Species Body rate(FMR) consumed dicrotoplzos in Daily dose BirdLD50 Risk (Based on weight(g) (kcal/day) perday daily diet (mg!kg bw/day) (mg!kgbw) Quotient ClosestBird (glday) (mg/day) Body Weight Cate}?ory) Using a 35-dhalf-life Indigo bunting (Passerina 14.50 15.73 9.21 0.62 42.8 4.92/8.37' 8.7/5.1b 463.3 cyanea) Northern cardinal (Cardinalis 44 36.13 16.69 0.59 13.4 4.92/8.37' 2.73/1.61b 463.3 cardinal is) American wigeon 756 304.06 174.73 16.09 21.3 8.37 2.5 65.8 (Anas americana) Usina a 3-dhalf-life Indigo bunting (Passerina 14.50 15.73 9.21 0.37 25.3 4.92/8.37' 5.1/30b 463.3 cyanea) Northern cardinal (Cardinalis 44 36.13 16.69 0.35 7.9 4.92/8.37' 1.6/09b 463.3 cardinalis) American wigeon (Anas 756.0 304.06 174.73 9.51 12.6 8.37 1.5 65.8 americana)

- Grue and Shipley (1986) reported LDSO values for nestlmgs and adult males for the European starling (Stumus vulgarus). The nestling LDSO was 4.92 mg**a~_/kg** bw and the adult male LDSO was 8.37 mgai/kgbw. b-Risk quotients for nestlings (higher number) and adults based on differing LDSO values for European starlings.

Page 52 of56TableA-2 Mammalian Total Daily Intake Model Results T-REXShort Field Massofprey Mass of LD50scaled GrassRQ Body metabolic rate consumed dicrotophos in Daily dose to surrogate Risk (Basedon Species weight (FMR) perday daily diet (mglkg bw/day) species body Quotient Closest (g) (kcal/day) (g!day) (mglday) weight (mglkg MammalBody bw)) Weight Category) Using a 35-dlzalBife Female meadowvole (Microtus 33.8 15.0 22.0 3.2 93.4 14.4 5.6 9.8 pennsylvanicus) Male meadow vole (Microtus 33.8 15.0 22.0 3.2 93.4 19.7 4.1 9.8 pennsylvanicus) Female deer (Odocoileus 45000 3427 7229 954 21.2 2.4 8.9 5.2 virginianus) Male deer (Odocoileus 45000 3427 7229 954 21.2 3.3 6.5 5.2 virginianus) Usinf! a 3-dhalf-life Female meadow vole (Microtus 33.8 15.0 22.0 1.9 55.2 14.4 3.8 9.8 pennsylvanicus) Male meadow vole (Microtus 33.8 15.0 22.0 1.9 55.2 19.7 2.8 9.8 pennsylvanicus) Female deer (Odocoi/eus 45000 3427 7229 564 12.5 2.4 5.3 5.2 virginianus) Male deer (Odocoileus 45000 3427 7229 564 12.5 3.3 3.8 5.2 virginianus)

Page 53 of56

# APPENDIX B EllS Incident Reports for Dicrotophos

Page 54 of56

# EHS Pesticide SununaryReport: General Infonnation Oicrotopbos (035201)

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Page 56 of56

# Appendix 4TITLE: Response to the Data Evaluation Record on the Fish Early Life Stage Toxicity of Dicrotophos Technical to Fathead Minnow (Pimephales prome/as), EPA MRID Number 48482901

Author: ABC Labs

Sponsor: AMVAC Chemical Corporation 4695 MacArthur Court, Suite 1200 Newport Beach, CA 92026

Date: November 6, 2014



### P1NO ClAIM OF CONFIDENTIALITY

No claim of confidentiality, on any basis whatsoever, is made for any information contained in this document. I acknowledge that information not designated as within the scope of FIFRA sec. lO(d)(l)(A),(B}, or 

### (C) on which pertains to a registered or previously registered pesticide is not entitled to confidential treatment and may be released to the public, subject to the provisions regarding disclosure to multinational entities under FIFRA lO(g}.

Submitter: Date:

Typed name of signer: Jon C. Wood Director of Registrations

Typed name ofcompany: AMVAC Chemical Corporation



### P2STATEMENT OF GLP COMPLIANCE This technical document provides information that assesses the benefits of use ofdicrotophos. The document does not contain any new or original data. Therefore, the requirements of40 CFR Part 160 are not appropriatetothis document.

Submitter/Sponsor: Date:

Typed name ofsigner: Jon C. Wood Director of Registrations

Typed name of company: AMVAC Chemical Corporation



## P3betterinsight betteroutcomes www.abclabs.com

November 6, 2014

RE: Response to the Data Evaluation Record on the Fish Early Life Stage Toxicity of Dicrotophos Technical to Fathead Minnow (Pimephales promelas),' EPA J\1RID Number 48482901 ·
INTRODUCTION: The document titled 'Data Evaluation Record on the Fish Early Life Stage Toxicity of Dicrotophos Technical to FatheadMinnow (Pimephalespromelas),' EPA l\.1RJD Number 48482901, has been reviewed by ABC Laboratories. The study deficiencies and conclusion stated in this document are discussed below. Based on its review oftheEPA DER, and EPA's rationale for classifyingthe study "supplemental,"ABC Laboratories is providing responses to the issues raised in EPA's review ofthis study, and believes the studyshouldbeupgradedto "core." STIJDYDEFICIENCIES CITED BYEPA: TheEPAreview cited two study deficiencies indeciding to classifythe dicrotophos early life stage study "supplemental" rather than core. These deficiencies include: 1. The redistribution oflarvae in the control on day seven violated the assumption of independence ofreplicates. On study day 7 (i.e., day 2 post-hatch), all live larvae were counted and released into their respe<O-tive replicate growth chamber; however,- larvae from two control replicates were inadvertently added to the same replicate growth chamber. The biological observations had already been recorded for both replicates prior to the inadvertent pooling oflarvae. Redistribution was elected by the study authors for these two replicates ofthe control, with larvae divided according to the initial number recorded for each replicate. The redistribution oflarvae in control replicates is a violation ofindependence ofreplicates andtherefore calls the statistical conclusions andthe integrity ofthe study husbandry into question; however, because none ofthe endpoints were significantly affected that would skewthe results, the reviewer determinedthe redistribution didnotimpactthe integrity of the study. 2. Dryweights (24 hours at 60°C) arepreferableto wet weights (blotted dry). 

### Ifthe fish exposed to the test material appear 

### to be edematous compared to control fish,
Page 1of4

4780 Discovery Drive • Columbia, Missouri 65201**80~~.5227** 7200 E. ABC Lane • Columbia, Missouri 65202**~** :determination of dry rather than wet weight is recommended. Since edema was observedintreated fish, wetweight measurements inthis study are notreliable. These deficiencies impactthe acceptability ofthe study. EPA's Conclusions: The redistribution of fry in control replicates is a violation of independence of replicates and, in conjunction withthe weightmeasurementmethods (i.e., wet weights in lieu ofdry weights), calls the integrity ofthe study conduct into question; however, this study provides information useful for risk characterization and is classified as SUPPLEMENTAL. No treatment-related effects on egg hatchability, time to start or complete hatch, larval survival, or growth were observed during exposure to dicrotophos technical at up to 9.88 mg ai/L, the highest mean measured concentration tested. In addition, there were no treatment-related clinical signs oftoxicity atany exposure leveL

ABC LABORATORIES RESPONSE: BelowareABC Laboratories responses to the study deficiencies cited byEPA and EPA's conclusions for ABC Laboratories Inc. Study No. 66150 titled, 'Dicrotophos Technical: Early Life-Stage Toxicity Test with the Fathead Minnow, Pimephalespromelas, Under Flow-ThroughTest Conditions.' Cited StudyDeficiencies: 1. The redistribution oflarvae in the control on day seven violated the assumption of independence ofreplicates. ABC Laboratories Response: ABC Laboratories agrees thatthe redistribution oflarvae on study day 7 did not impact the integrity ofthe study because none ofthe endpoints were significantly affected that would skew the results. The redistribution was the result of a technical oversight at the time hatched fry were released from the egg incubation cups. At the time this event occurred, study day 7 (i.e., day 2 post-hatch), all live fry were counted and released into their respective replicate growth chamber; however, fry from control replicate D were inadvertently added to control replicate C test chamber which already contained the fryreleased into its ownrespective chamber. The biological observations had already been recorded for both of these replicates prior to the inadvertent pooling of fry. All fry present in control replicate C, after inadvertent pooling, were removed and divided according to the initial number recorded for each replicate, withthe appropriate numberplacedin control replicates C & D. After fry were separated, the biological observations were performed again for these replicates. Since this inadvertent error occurred only withtwo ofthe control replicates, redistribution was the best alternative for continuing the exposure as well as minimizing the number of vertebrates sacrificed forthe study.

Page 2 of4 

### P5 I IIt is important to recall the overall design ofthe diluter and exposure chamber testing apparatus. Flows ofcontrol dilution water (and test solutions) are first split to the A and B replicates and the C andD replicates. The dilution water ottest solution flows to the A and B replicates, and the C and D replicates, are subsequently split again, for separate flows to eachreplicate. Therefore, the dilution water andtest solution flows to theA and B replicates, andthe C and D replicates using this test apparatus set-up are more closely linked thanflows to the A and C replicates, or the B and D replicates. Measurements of dilution water flows 

### to these control replicates were within 10% ofthe mean flow rates, and there were no differences between the C and D replicates in terms of key environmental factors, such as dissolved oxygen, temperature, or pH, which, ifdifferent, may have affected fry survival and growth. However, there were no differences between the C andD replicates duringthe studyfor thesekeyenvironmental factors. ABC Laboratories also notes that this technical error involved only control fish, so there was no potential for slightly different exposures to the test material, as might occur in replicates from a treatment group. As noted above, there were no differences during the study, either before or after day 7, between the control replicates in terms of key environmentalparameters thatcouldimpactfry growth or survival. Anotherkey consideration is**tha~** this inadvertentmixing offry from the control C and D replicates occurred very early inthe study, atthe tii:ne the fry were released from the egg incubation cups. The key endpoint evaluated at this stage of the study is hatching success. There were no significant differences in hatching success betweenthe C and D replicates. Effects on the typically more sensitive test endpoints of growth (fry weight and length) and overall fry survival were not evaluateduntil several weeks later, at study termination. There were also no immediate, or short-term effects on fry survival in either the CorD control replicate. On the contrary, observations of the fry in these two replicates remained consistentthroughout theremainder ofthe exposureperiod. One ofthe criteria listed in the DER (Table 1) is that each treatment should include a minimum of20 embryos per replicate cup and a minimum of 30 fish per treatment for post-hatch exposure. This criterion would still be met if the two control replicates associated with the redistribution oflarvae were excluded from the statistical analyses. Additionally, the OPPTS 850.1400 test guideline only requires at least two replicates; however, studies of this nature conducted at ABC Laboratories routinely utilize four replicates per treatment, which increases the statistical power to detect differences betweenthe treatment groups and the controls. The fry survival and growth (length and weight) datawere statistically evaluated againstthe two controlreplicates (replicates A & B) not associated with the redistribution oflarvae. This evaluation con:finned that there were no differences between the two sets ofcontrol replicates (replicates A and B and replicates C and D), and more importantly, confirmed that the NOEC remained unchangedfor alltestparameters.

Page 3 of4 

### P62. Dry weights (24 hours at 60°C) are preferable to wet weights (blotted dry). Ifthe fish exposed to the test material appear to be edematous compared to control fish, determination of dry rather than wet weight is recommended. Since edema was observed intreated fish, wetweight measurements 

### inthis study are notreliable. ABC Laboratories Response: The fish appearing to be edematous were observed early in the study on study days 3, 4, and 5. One edometous fish was observed in the 0.327 mg/L test group on study day 3. On study day 4 there were two edometous fish in the control (replicate C), three edometous fish in the 0.327 mg/L (one in replicate C and two inreplicate D) test group, and one edometous fish in the 1.21 mg/L (replicate A) test group. On study day 

### 5there was one edometous fish inreplicate C ofthe 1.21 mg!L test group. The daily clinical observations beginning with study day 5 (day 0 post-hatch; start ofthe 28-day post-hatch exposure) are presented inthe attached appendix. As shown in this appendix, all fish surviving at test termination were normal in appearance; therefore, blotted wetweightmeasurements were appropriate at testtermination. The fish were exposed for four weeks after the last observation of an edometous fish. Any fish thatwere observed as edometous before the 28-daypost-hatchperiod, oron day 0 ofthe post-hatch period, either were early mortalities (by day 1 post-hatch) or were fully normal in appearance by day 1post-hatch and throughouttheremainder ofthe posthatch exposure period. If the edometous fish were the mortalities before or at the beginning ofthe post-hatch phase ofthe study, they clearly had no impact on the fish weights recorded at testtermination. Ifthe fishreported 

### as edometous on orbefore day 0 of the post-hatch period survived until termination, they were normal in appearance through theremainder ofthe study, andtherefore edemawas clearly not a factor whenthe fish were weighed at testtermination. Conclusion: Based on these cited deficiencies, the study reviewer classified the study as SUPPLEMENTAL. However, as described above, the inadvertent mingling offish from two closelylinked control replicates early inthe study did notresult in any trend or effect on sensitive test endpoints determined at study termination. The EPA reviewer determined that this inadvertent mingling offish from two control replicates early in the study did not impact study integrity. Thefew edometous fish observed on or before day 0 ofthe post-hatchperiod were not observed at any later time points, and specifically, no edometous 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 that the study classification should be upgraded to a CORE classification.
Prepared By:

# ~JU..... c/.

# ~~~ Stephen

### L. Hicks Senior Scientist/Study Director ABC Laboratories, Inc. Page4 of4 

### P7 Dme:

___**O_~~'_AJ._v_· ~v.~;rf----**  I I. . :. ·. .- . ··--

Appendix Table 1. HatchedFry CumulativeMortality andClinical Observations During the 28-Day Post-HatchPeriod ofFatheadMinnows Exposedto DicrotophosTechnical (ABC StudyNo. 66150)

Page 1 of9



### P8Table 1. Hatched Fry Cumulative Mortality and Clinical Observations During the 28-DayPost-HatchPeriod ofFathead Minnows Exposedto Dicrotophos Technical (ABC StudyNo. 66150)

Mean Measured Number Da 0 2 Da 1 Da 2 Day3 Concentration Larvae No. Effects 4 No. Effects 4 No. Effects 4 No. Effects 4

(mg a.i.IL) Rep. Hatched 1 Dead 3 Dead 3 Dead 3 Dead 3

Control A 19 0 18 AN 0 19AN 0 17 AN,2B 0 17 AN,2NF B 20 0 20AN 0 20AN 0 20AN 0 20AN 

### c 19 0 17 AN 2 17 AN 2 14AN; 3 B 2 14AN; 2B; 1NF D 17 0 16AN; 1 B 0 16AN;1B 0 16 AN; 1 B 0 15 AN; 1B; I NF 0.327 A 20 0 20AN 0 20AN 0 19 AN; 1 B 0 19 AN; I NF B 20 0 19AN 0 20AN 1 19AN 1 19AN 

### c 20 1 19AN I 19AN 1 19 AN 1 19AN D 18 2 16AN 2 16AN 2 16AN 2 15 AN; 1NF 0.590 A 20 0 19AN 1 19AN 1 19AN 2 18 AN B 16 0 15 AN; 1NF 0 16AN 1 15 AN 1 15AN 

### c 16 I 14AN 4 12AN 4 12AN 4 12AN D 20 0 20AN 0 20AN 0 20AN 0 20AN ""0 1.21 A 20 1 18 AN 2 17 AN 2 18AN 2 18 AN w B 20 0 19 AN; 1 B 1 19AN I 19AN 1 19 AN 

### c 20 0 18 AN; 1ED; 1 B 1 19AN 2 18AN 2 18AN D 19 0 .19AN 0 19AN 0 19 AN 0 19AN 2.45 A 20 0 20AN 0 20AN 0 20AN 0 20AN B 20 0 19AN 0 19AN 0 20AN 0 20AN 

### c 20 0 20AN 0 20AN 1 19AN 1 19AN D 19 0 19AN 0 19AN 0 19 AN 0 19 AN 4.94 A 19 0 18AN;1NF 0 18 AN; 1 1 18AN 2 16 AN; 1NF NF B 20 0 19AN; 1 B 0 19 AN; 1 B 0 18 AN; 2B 1 19AN 

### c 19. 1 17 AN; 1 B 2 17 AN 2 17 AN 2 17 AN D 18 0 18AN 0 18 AN 0 18 AN 0 18 AN 9.88 A 

### !9 0 19AN 1 18AN 1 18 AN 3 16AN B 18 0 18AN 0 18 AN 0 18 AN 0 18 AN 

### c 20 0 20AN 0 20AN 0 19 AN; 1 B 1 19AN D 20 0 18AN;2B 1 19AN 1 18 AN; 1B 1 18 AN; 1NF 1Cumulative number ofhatched larvae during the study. Some larvae had not yet hatched by day 0 post-hatch; therefore, the fry not accounted for on post-hatch observation days were not yet hatched. 2 Day 0post-hatch=Day 5 oftest. 3 Cumulative number ofdead fish. 4 Effects: AN= appear normal; B =onbottom; ED= edema; NF =not found.**~Page** 

### 2 of9- .ABC Study No. 66150Table 1. HatchedFry Cumulative Mortality and Clinical Observations During the 28-Day Post-Hatch Period ofFathead Minnows Exposedto Dicrotophos Technical (ABC StudyNo. 66150) (continued)

Mean Measured Number Da 4 Da 5 Da 6 Day7 Concentration Larvae No. Effects 2 No. Effects 2 No. Effects 2 No. Effects 2

(mg a.i.IL) Rep. Hatched Dead 1 Dead 1 Dead 1 Dead 1

Control A 19 0 18AN,1NF 0 18 AN, 1NF 0 17 AN, 2NF 0 17AN,2NF B 20 1 19AN 3 17 AN 3 17 AN 3 17 AN 

### c 19 3 13 AN; 1 B; 2 NF 3 14AN; 1 B; 1NF 4 13 AN; 1 B; 1NF 4 13 AN; 2NF D 17 2 15 AN 3 14AN 3 14AN 3 14AN 0.327 A 20 1 19 AN 2 18 AN 2 18AN 2 18 AN B 20 2 18 AN 2 18AN 2 18AN 2 18 AN 

### c 20 2 18AN 2 18AN 2 18 AN 2 18 AN D 18 2 16 AN 2 16AN 3 15 AN 3 15 AN 0.590 A 20 2 l8AN 2 18AN 2 18 AN 2 18AN B 16 1 14AN; 1NF 1 14AN; 1NF 1 14AN; 1NF 1 14AN;1NF 

### c 16 4 12AN 4 12AN 4 12AN 4 12AN 

### -a D 20 0 20AN 0 20AN 0 20AN 0 20AN

....... 0 1.21 A 20 2 17AN;1B 3 17 AN 3 17 AN 3 17 AN B 20 2 18 AN 2 18AN 2 18 AN 2 18AN 

### c 20 3 17 AN 4 16AN 4 16AN 4 16AN D 19 0 19AN 0 19AN 0 19 AN 0 19 AN 2.45 A 20 0 20AN 0 20AN 0 20AN 0 20AN B 20 0 20AN 0 20AN 0 20AN 0 20AN 

### c 20 1 18AN;1NF 1 19AN 1 19AN 1 19AN D 19 0 19AN 0 19 AN 0 19 AN 0 19 AN 4.94 A 19 2 16 AN; 1NF 2 16AN;1NF 2 16 AN; 1NF 2 16AN; I NF B 20 1 18AN; 1NF 1 17AN;1B;1NF 1 17AN;2NF 1 18 AN; 1NF 

### c 19 2 17 AN 2 17 AN 2 17 AN 2 17 AN D 18 0 17AN;1NF 0 18AN 0 18AN 0 18 AN 9.88 A 19 3 16AN 3 16AN 3 16AN 3 16AN B 18 0 18 AN 0 17AN;1NF 0 17AN;1NF 0 17AN;1NF 

### c 20 1 19AN 1 19AN 2 18 AN 2 18AN D 20 1 19AN 1 19AN 2 18 AN 2 18 AN Cumulative number ofdead fish. 2 Effects: AN= appear no11nal; B =onbottom; NF=notfound. -Page 3 of9- .ABC Study No. 66150

### Table 1. Hatched Fry Cumulative Mortality and Clinical Observations During the 28-Day Post-Hatch Period ofFathead Minnows Exposed to Dicrotophos Technical (ABC StudyNo. 66150) (continued)

Mean Measured Number Da 8 Da 9 Da 10 Day 11 Concentration Larvae No. Effects 2 No. Effects 2 No. Effects 2 No. Effects 2

(mg a.i./L) Rep. Hatched Dead 1 Dead 1 Dead 1 Dead 1

Control A 19 0 17 AN, 2NF 0 17 AN, 2NF 0 17 AN,2NF 0 17 AN, 2NF B 20 3 17 AN 3 17 AN 3 17 AN 3 17 AN 

### c 19 4 13 AN; 2NF 4 13 AN; 2NF 4 13AN;2NF 4 13AN;2NF D 17 3 14AN 3 14AN 3 14AN 3 14AN 0.327 A 20 2 18 AN 2 18 AN 2 18AN 2 18AN B 20 2 18 AN 2 18 AN 2 18 AN 2 18 AN 

### c 20 2 18AN 2 IS AN 2 !SAN 2 !SAN D 18 3 15 AN 3 15AN 3 15 AN 3 15AN 0.590 A 20 2 IS AN 2 18 AN 2 18 AN 2 18 AN B 16 1 14AN;INF 1 14AN; 1NF 1 14AN;1NF 1 14AN; I NF 

### c 16 4 12AN 4 12AN 4 12AN 4 12AN ""C D 20 0 ·20AN 0 20AN 0 20AN 0 20AN
_. _. 1.21 A 20 3 17 AN 3 17 AN 3 17 AN 3 17 AN B 20 2 18AN 2 18 AN 2 18AN 2 18 AN 

### c 20 4 16AN 4 16 AN 4 16 AN 4 16AN D 19 0 19 AN 0 19 AN 0 19AN 0 19AN 2.45 A 20 0 20AN 0 20AN 0 20AN 0 20AN B 20 0 20AN 0 20AN 0 20AN 0 20AN 

### c 20 1 19AN 1 19AN 1 19 AN 1 19 AN D 19 0 19 AN 0 19 AN 0 19AN 0 19AN 4.94 A 19 2 16AN;INF 2 16 AN; 1NF 2 16AN;INF 2 16AN; 1NF B 20 1 17AN;2NF 1 17AN;2NF 1 17 AN;2NF 1 17 AN;2NF 

### c 19 2 17 AN 2 17 AN 2 17 AN 2 17AN D 18 0 18 AN 0 18AN 0
. 18AN 0 18 AN 9.88 A 19 3 16AN 3 16AN 3 16AN 3 16AN B 18 0 17 AN; 1NF 0 17 AN; 1NF 0 17 AN; 1NF 0 17AN;INF 

### c 20 2 !SAN 2 !SAN 2 18 AN 2 !SAN D 20 2 !SAN 2 18 AN 2 18 AN 2 IS AN Cumulative number ofdead fish. 2 Effects: AN= appear normal; NF=not found. -Page 4 of9- ABC StudyNo. 66150Table 1. Hatched Fry Cumulative Mmiality and Clinical Observations During the 28-Day Post-HatchPeriod ofFathead Minnows Exposedto Dicrotophos Technical (ABC StudyNo. 66150) (continued)

Mean Measured Number Da 12 Da 13 Da 14 Day 15**Conce~tration** Larvae No. Effects 2 No. Effects 2 No: Effects 2 No. Effects 2

(mg a.i.IL) Rep. Hatched Dead 1 Dead 1 Dead 1 Dead 1

Control A 19 0 17AN,2NF 0 17 AN,2NF 0 17 AN, 2 NF 0 17AN,2NF B 20 3 17 AN 3 17 AN 3 17 AN 3 17 AN 

### c 19 4 13 AN; 2NF 4 13 AN; 2NF 4 13 AN; 2NF 4 13 AN; 2NF D 17 3 14AN 3 14AN 3 14AN 3 14AN 0.327 A 20 2 18AN 2 18AN 2 18AN 2 18 AN B 20 2 18AN 2 · 18AN 2 18AN 2 18 AN 

### c 20 2 18AN 2 18 AN 2 18 AN 2 18 AN D 18 3 15AN 3 15 AN 3 15AN 3 15 AN 0.590 A 20 2 18 AN 2 18AN 2 18 AN 2 18 AN B 16 1 14AN; 1NF 1 14AN; 1 NF 1 14AN;1NF 1 14AN; 1NF 

### c 16 4 12AN 4 12AN 4 12AN 4 12AN '"0 D 20 0 20AN 0 20AN 0 20AN 0 20AN



### ...... N 1.21 A 20 3 17 AN 3 16AN; 1NF 3 16AN; 1 NF 3 16 AN; 1NF B 20 2 18 AN 2 18AN 2 18 AN 2 18AN ::· 

### c 20 4 16AN 4 16AN 4 16 AN 4 16AN D 19 0 19AN 0 19AN 0 19AN 0 19AN 2.45 A 20 0 20AN 0 20AN 0 20AN 0 20AN B 20 0 20AN 0 20AN 0 20AN 0 20AN 

### c 20 1 19 AN 1 19AN 1 19AN 1 19AN D 19 0 19AN 0 19AN 0 19AN 0 19AN 4.94 A 19 2 16 AN; 1NF 2 16 AN; 1NF 2 16 AN; 1NF 2 16AN; 1NF B 20 1 17 AN; 2NF 1 17 AN; 2NF 1 17 AN; 2 NF 1 17AN;2NF 

### c 19 2 17 AN 2 17 AN 2 17 AN 2 17 AN D 18 0 18AN 0 18AN 0 18AN 0 18AN 9.88 A 19 3 16AN 3 16AN 3 16AN 3 16AN B 18 0 17AN;1NF 0 17AN;1NF 0 17AN;1NF 0 17 AN; 1NF 

### c 20 2 18 AN 2 18AN 2 18AN 2 18AN D 20 2 l8AN 2 18 AN 2 18 AN 2 18 AN 1 Cumulative number ofdead fish. 2 Effects: AN= appearnonnal; NF=not found. -Page 5 of9- .ABC StudyNo. 66150Table 1. HatchedFry Cumulative Mortality and Clinical Observations During the 28-Day Post-HatchPeriod ofFathead Minnows Exposedto Dicrotophos Technical (ABC StudyNo. 66150) (continued)

MeanMeasured Number Da 16 Da 17 Da;_: 18 Da;_: 19 Concentration Larvae No. Effects 2 No. Effects 2 No, Effects 2 No. Effects 2

(mg a.i.IL) Rep. Hatched Dead 1 Dead 1 Dead 1 Dead 1

Control A 19 0 17 AN, 2NF 0 17 AN,2NF 0 17 AN, 2NF 0 17 AN, 2NF B 20 3 17 AN 3 17 AN 3 17 AN 3 17 AN c 19 4 13 AN; 2 NF 4 13 AN; 2NF 4 13 AN; 2NF 4 13 AN; 2NF D 17 3 14AN 3 14AN 3 14AN 3 14AN 0.327 A 20 2 18AN 2 18 AN 2 18AN 2 18AN B 20 2 18 AN 2 18AN 2 18 AN 2 18AN c 20 2 18 AN 2 18 AN 2 18AN 2 18AN D 18 3 15 AN 3 15AN 3 15 AN 3 15 AN 0.590 A 20 2 18 AN 2 18AN 2 18 AN 2 18AN B 16 1 14AN; 1NF 1 14 AN; 1NF 1 14 AN; 1NF 1 14AN; 1NF 

### c 16 4 12AN 4 12AN 4 12AN 4 12AN '"'0 D 20 0 20AN 0 20AN 0 20AN 0 20AN

....... 

### w 1.21 A 20 3 16 AN; 1NF 3 16 AN; 1NF 3 16 AN; 1NF 3 16 AN; 1NF B 20 2 18 AN 2 18 AN 2 18AN 2 18 AN 

### c 20 4 16 AN 4 16AN 4 16AN 4 16AN D 19 0 19 AN 0 19AN 0 19AN 0 19 AN 2.45 A 20 0 20AN 0 20AN 0 20AN 0 20AN B 20 0 20AN 0 20AN 0 20AN 0 20AN 

### c 20 1 19AN 1 19AN 1 19AN 1 19 AN D 19 0 19AN 0 19AN 0 19 AN 0 19 AN 4.94 A 19 2 16AN;1NF 2 16 AN; 1NF 2 16AN; 1NF 2 16 AN; 1NF B 20 1 17 AN; 2NF 1 17AN;2NF 1 17 AN;2NF 1 17AN;2NF 

### c 19 2 17 AN 2 17 AN 2 17 AN 2 17 AN D 18 0 18 AN 0 18 AN 0 18AN 0 18 AN 9.88 A 19 3 16AN 3 16AN 3 16AN 3 16AN B 18 0 17 AN; 1NF 0 17 AN; 1NF 0 17AN;1NF 0 17AN;1NF 

### c 20 2 18 AN 2 18AN 2 18AN 2 18 AN D 20 2 18AN 2 18 AN 2 18 AN 2 !SAN Cumulative number ofdead fish. 2 Effects: AN= appearnonnal; NF =not found.

-**Pag1~** 

### 6of9- ABC Study

### No. 66150Table 1. Hatched Fry Cumulative Mortality and Clinical Observations During the 28-DayPost-HatchPeriod ofFathead Minnows Exposedto Dicrotophos Technical (ABC StudyNo. 66150) (continued)

Mean Measured Number Dar20 Dar21 Da 22 Daz23 Concentration Larvae No. Effects 2 No. Effects 2 No. Effects 2 No. Effects 2

(mg a.i.!L) Rep. Hatched Dead 1 Dead 1 Dead 1 Dead 1

Control A 19 0 17 AN, 2NF 0 17 AN, 2NF 0 17 AN, 2NF 0 ARAN B 20 3 17 AN 3 17 AN 3 17 AN 3 ARAN 

### c 19 4 13 AN; 2NF 4 13 AN; 2NF 4 13 AN; 2NF 4 ARAN D 17 3 14AN 3 14AN 3 14AN 3 ARAN 0.327 A 20 2 18 AN 2 18 AN 2 18 AN 2 ARAN B 20 2 18 AN 2 18 AN 2 18 AN 2 ARAN 

### c 20 2 18 AN 2 18AN 2 18AN 2 ARAN D 18 3 15 AN 3 15 AN 3 15 AN 3 ARAN 0.590 A 20 2 18AN 2 18 AN 2 18AN 2 ARAN B 16 1 14AN; 1NF 1 14AN; 1NF 1 14 AN; 1NF 1 ARAN 

### c 16 4 11AN 4 11AN 4 12AN 4 ARAN -o D 10 0 lOAN 0 lOAN 0 lOAN 0 ARAN



## ..... ..j::o. 1.11 A 10 3 16AN;1NF 3 16AN;1NF 3 16AN;1NF 3 ARAN B 10 1 18AN 2 18 AN 1 17 AN 1 C 2 ARAN 

### c 10 4 16AN 4 16AN 4 16AN 4 ARAN D 19 0 19 AN 0 19AN 0 19AN 0 ARAN 2.45 A 20 0 lOAN 0 lOAN 0 lOAN 0 ARAN B 10 0 lOAN 0 lOAN 0 lOAN 0 ARAN 

### c 10 1 19AN 1 19AN 1 19 AN 1 ARAN D 19 0 19 AN 0 19AN 0 19AN 0 ARAN 4.94 A 19 1 16 AN; 1NF 1 16AN;1NF 2 16 AN; 1NF 1 ARAN B 10 1 17 AN; 2NF 1 .17 AN; 2NF 1 17 AN; 1NF 1 ARAN 

### c 19 1 17 AN 2 16 AN; 1NF 2 16 AN; 1NF 2 ARAN D 18 0 18AN 0 18 AN 0 18AN 0 ARAN 9.88 A 19 3 16 AN 3 16AN 3 16AN 3 ARAN B 18 0 17AN;1NF 0 17AN;1NF 0 17AN;1NF 0 ARAN 

### c 10 1 18 AN 2 18AN 1 18AN 1 ARAN D 20 2 18 AN 2 18AN 2 18AN 1 ARAN Cumulative number ofdead fish. 2 Effects: AN= appearnonnal; C =spinal curvature; NF =not found; ARAN = all remaining surviving fish appear nonnal.**~Page** 

### 7 of9- ABC Study No. 66150

··--------·- -------------·-- .Table 1. Hatched Fry Cumulative Mortality and Clinical Observations During the 28-DayPost-HatchPeriod ofFathead Minnows Exposedto Dicrotophos Technical (ABC StudyNo. 66150) (continued)

Mean Measured Number Da 24 Da.J::25 Dax26**Da~27** Concentration Larvae No. Effects 2 No. Effects 2 No. Effects 2 No. Effects 2

(mg a.i./L) Rep. Hatched Dead 1 Dead 1 Dead 1 Dead 1

Control A 19 0 17 AN, 2NF 0 17 AN, 2 NF 0 17 AN, 2NF 0 17 AN,2NF B 20 3 17 AN 3 17 AN 3 17 AN 3 17 AN 

### c 19 4 13 AN; 2NF 4 13 AN;2NF 4 13 AN; 2NF 4 13AN;2NF D 17 3 14AN 3 14AN 3 14AN 3 14AN 0.327 A 20 2 18AN 2 18 AN 2 18 AN 2 18AN B 20 2 18 AN 2 18 AN 2 18 AN 2 18AN 

### c 20 2 18AN 2 18AN 2 18AN 2 18 AN D 18 3 15 AN 3 15 AN 3 15 AN 3 15 AN 0.590 A 20 2 1'8AN 2 18AN 2 18AN 2 18 AN B 16 1 14AN;1NF 1 14AN; 1NF 1 14AN;1NF 1 14AN; I NF 

### c 16 4 12AN 4 12AN 4 12AN 4 12AN -u D 20 0 20AN 0 20AN 0 20AN 0 20AN



## ..... CJ'1 1.21 A 20 3 16 AN; 1NF 3 16AN;1NF 3 16 AN; 1NF 3 16 AN; I NF B 20 2 18 AN 2 18AN 2 18AN 2 18 AN 

### c 20 4 16AN 4 16 AN 4 16AN 4 16AN D 19 0 19AN 0 19AN 0 19 AN 0 19AN 2.45 A 20 0 20AN 0 20AN 0 20AN 0 20AN B 20 0 20AN 0 20AN 0 20AN 0 20AN 

### c 20 1 "19AN 1 19AN 1 19AN 1 19AN D 19 0 19 AN 0 19 AN 0 19AN 0 19 AN 4.94 A 19 2 16 AN; 1 NF 2 16 AN; 1NF 2 16 AN; 1NF 2 16 AN; 1NF B 20 1 17 AN; 2 NF 1 17AN;2NF 1 17 AN;2NF 1 17AN;2NF 

### c 19 2 16 AN; 1NF 2 16 AN; 1NF 2 16AN;1NF 2 16 AN; 1 NF D 18 0 18 AN 0 18 AN 0 18AN 0 !BAN 9.88 A 19 3 16AN 3 16AN 3 16AN 3 16AN B 18 0 17 AN; 1NF 0 17 AN; 1 NF 0 17AN;1NF 0 17 AN; 1NF 

### c 20 .2 18 AN 2 18AN 2 18 AN 2 18 AN D 20 2 18 AN 2 18AN 2 18 AN 2 18 AN Cumulative number ofdead fish. 2 Effects: AN = appearnonnal; NF =notfound. 

### -Page 8 of9- ABC. StudyNo. 66150

-----**~-** -- -· .. - ·----·----- . -------·-····· ---- ·--· - ----------------- --- ----·- . ·····-------------- ····--···-··Table 1. HatchedFry Cumulative Mortality and Clinical Observations During the 28-Day Post-Hatch Period ofFathead Minnows Exposedto Dicrotophos Teclmical (ABC StudyNo. 66150) (continued)

Mean Measured Number Day 28 Concentration Larvae No. 2

(mg a.i./L) Rep. Hatched Dead I Effects

Control A 19 2 I 7 AN, 2NF B 20 3 17 AN C 19 6 13AN;2NF D 17 3 14 AN 0.327 A 20 2 18 AN B 20 2 18 AN C 20 2 18 AN D 18 3 ·15AN 0.590 A 20 2 .18 AN B 16 2 14 AN; 1NF C 16 4 12 AN D 20 0 20AN

### ~ 1.21

### ~**~~** 

# i 16

### ~rl~NF C 20 4 16 AN D 19 0 19 AN 2.45 A 20 1 .J9 Al'J; 1NF B 20 0 20 AN C 20 1 19 AN D 19 0 19 AN 4.94 A 19 3 16AN; 1NF B 20 3 17 AN; 2 NF C 19 3 16AN;1NF D 18 0 18 AN 9.88 A 19 3 16 AN B 18 1 17AN;1NF C 20 2 18 AN D 20 2 18 AN 1 Cumulative number ofdead fish. Fish counted as not found at test te1mination added to cumulative number ofdead. 2 Effects: AN= appear nonnal; NF=notfound.

-Page 9 of9- ABC StudyNo. 66150