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UNITED STATES EI\VIRONMENTAL PROTECTION AGENCY WASHINGTON D.C..20460

PC Code: 080803
DP Barcode: 415839 December 6,2013 MEMORANDUM

Subject:

To:

From: Environmental Fate and Effects Division's Response to Public Comments on

the Registration Review Preliminary Problem Formulation for Atrazine

Kaitlin Keller, Chemical Review Manager
Patricia Parrott, Branch Chief
Risk Management and Implementation Branch 

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Pesticide Re-evaluation Division (7508P)

Frank Famrggia, Ph.D., Biologist Amy Blankinship, M.S., Chemist

James Hetrick, Ph.D., Senior Advisor
Environmental Risk Branch 

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Environmental Fate and Effects Division (7507P)

Through: 

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Environmental fusk Branch 

### III

Environmental Fate and Effects Division (7507P)

This document contains the Environmental Fate and Effects Division's (EFED's) responses to

comments received on the Atrazine Registration Review Preliminary Problem Formulation (EPA-HQ-OPP-2013-0266). Comments have been organized according to the following topic areas; 1) effects on aquatic plants, 2) ecotoxicity to animals, 3) bias factors, and 4) endangered species risk assessment and protection. Comment summaries and EPA's

response to comments are shown below.

Effects on Aquatic Plants



### 1. Comment Summary (Syngenta): There is research available demonstrating the

recovery of aquatic plants from atrazine exposure. A list of publications was provided.

EFED Response: As described in the 2012 FIFRA Scientific Advisory Panel (SAP)
white paper (USEPA 2012) and in the addendum to the Problem Formulation (USEPA 2013) for the Preliminary Risk Assessment, EFED intends to consider the Dana Spatz, Branch 

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Rosanna Louie-Juzwiak, Ri sk Asse3sment Process2

potential for recovery of individual species after exposure to atrazine has stopped, and considers the recovery of communities to be quite different than that of the individual species. EFED will consider the literature that was cited by Syngenta in their comments as part of the preliminary risk assessment.

2. Comment Summary (Syngenta) : A comprehensive scientific evaluation of the micro/mesocosm dataset was completed by Giddings in 2012 and provided several conclusions that Syngenta and Giddings presented to the SAP in 2012.

EFED Response : As stated in the Addendum to the Problem Formulation (USEPA 2013) , EPA wil l consider the information presented during the SAP , including the Giddings 2012 report, and will also evaluate and include, as appropriate, additional studies prior to conducting the preliminary risk assessment.

3. Comment Summary (Syngenta) : An evaluation of the sensitivity of the EPA’s methodology for specifying an LOC for atrazine using the PATI model indicated that the model is sensitive to the cosm studies included and their scoring . Additionally

, assessment periods in the initial dataset identified by EPA were sometimes outside of the assessment window . T he Giddings 2012 report provide s the most accurate representation of the toxicity data.

EFED Response : As stated in the Addendum to the Problem Formulation (USEPA 2013) , EPA will conside r the information presented during the SAP , including the Giddings 2012 report regarding the sensitivity of the CE

- LOC methodology to cosm study selection, duration and scoring.

4. Comment Summary (Syngenta) : A few additional community

- scale research proje cts are underway or have been completed: r esearch on periphyton, aquatic macrophytes, benthic communities, and physical habitats of midwestern streams have been conducted; ongoing research investigating the sensitivity and potential recovery of native peri phyton communities following an atrazine exposure.

EFED Response: EPA will be conducting a literature search prior to writing the preliminary risk assessment

, and will also evaluate and include, as appropriate, submitted studies.

Ecotoxicity of Atrazine to Animals

1. Comment Summary (A nonymous commenter (1jx

- 8792

- ton7); Center for Biological Diversity; Beyond Pesticides; P ublic commenter, L. Markham; Syngenta ) : There were numerous comments that included open literature citations regarding testing of atrazi ne on aquatic and terrestrial orga nisms.

EFED R esponse : EFED will consider these studies for inclusion in the preliminary risk assessment for the registration review of atrazine.3

2. Comment Summary (Syngenta) : Syngenta supports the approach proposed by the
EPA (pg 11 of Addendum to the Atrazine Problem Formulation) regarding a comprehensive evaluation of the large data set of amphibian studies using atrazine. A publication manuscript regarding an analysis based on a quantitativ e weight of evidence approach of the available atrazine testing with amphibians will be provided to the EPA.

E FED R esponse : EFED will evaluate and consider the weight of evidence approach presented by Syngenta as EFED develops an integrated and comprehensive approach for evaluating the large set of toxicity data available for amphibians.

3. Comment Summary (Syngenta) : An analysis of available amphibian data was provided to evaluate potential differences in sensitivities with regard to Xenopus laev is and native species of North American amphibians (topic discussed on pg 13 of Addendum to the Atrazine Problem Formulation) . These analyses included discussion of the relative sensitivity to estradiol

, sex ratio , and other metrics considered as part of the Weight of Evidence analysis that will be submitted to EPA

.

EFED R esponse : EFED will consider these data provided in the sensitivity analyses and will continue to gather information by searching the open literature for papers that may be useful in eluc idating relevant pathways in amphibian species, as well as potential differences between them.

Development and Use of Bias Factors

1. Comment Summary (Syngenta) : Bias factor estimation should account for watershed characteristics, toxicity endpoint, and sampling design. Syngenta has conducted research to show that the magnitude of bias factors is dependent on normalize flow (reservoirs vs . flowing water), size of watershed, averaging time of the toxicity endpoint, and sampling design (Mosquin et al., 2011 a, b; Chen and Mosquin, 2012; Chen et al., 2013).

E FED Response : EFED ’s proposed approach for the development of bias factors is to consider the hydrology ( reservoirs versus flowing water), data interpolation methods, sampling strategy (systematic versus stratified random), and averaging time of the toxicity endpoint (60

- day average). EFED also will evaluate the referenced research papers (Mosquin et al., 201 1 a, b; Chen and Mosquin, 2012; Chen et al., 2013) on the relationship of bias factors to watershed size and flow to consider as part of the development of bias factors.

2. Comment Summary (Syngenta) : Bias factor

- estimated concentrations should be compared to the upper confidence bounds of the highest percentile (e.g., 99%) values statistically inferred from relevant historical multiple year and site data (Mosquin et al., 2012). This comparison provides a ground

- truth of bias factor estimate s with

q uantified uncertainty.4

E FED Response: EFED will evaluate the proposed statistical methods in Mosquin et al., 2012 for attempting to quantify the uncertainty in the bias factor

- adjusted concentration

.

3. Comment Summary (Syngenta) : Bias factor

- estimate d concentrations should not be used to identify vulnerable watersheds for atrazine runoff. Syngenta recommends that the use of models ( e.g. , PRZM Hybrid) incorporating environmental and agronomic factors in conjunction with extensive monitoring data (USGS and AEMP) is the most appropriate approach for selection of vulnerable watersheds.

E FED Response : EFED proposed that watershed vulnerability be determined using the same criteria used in selection of A trazine E cological M onitoring P rogram (AEMP) monitoring sites

. As noted in the Addendum to the Problem Formulation, i f watershed properties are outside the range of the criteria used for selection of AEMP monitoring sites, then an evaluation of available monitoring data using appropriate bias facto r adjustments or modeling approaches (Corn Belt WARP, National WARP, SEAWAVE) are proposed for assessing the need for additional monitoring within the watershed. These monitoring data would provide appropriate data to assess watershed vulnerability.

4. Comment Summary (Syngenta) : Data based regression models (such as SEAWAVE, WARP, etc.) are a valid approach for estimating daily atrazine concentrations from monitoring data or non

- monitored watersheds. However, the regression models need to be thoroughly evaluated and validated against all available measured data from the AEMP

, AMP, and other monitoring programs. Syngenta recommends that 10 to 20 data points for each parameter are needed to provide a statistically robust estimate from regressio n models (Harrell, 2000).

E FED Response: EFED agrees and will explore the potential use of regression models (SEAWAVE, C orn B elt WARP, National WARP) for estimating daily atrazine concentrations

.

EFED Response to Comments Related to Endangered Speci es Risk Assessment and Protection

EPA has reviewed the comments from Center for Biological Diversity, Envi ronmental Law and Policy Center, Center for Regulatory Effectiveness

, and Syngenta on the registration review docket openings for atrazine and plans to address many of the concerns raised as part of the implementation plan for assessing the risks of pesticides to listed species based on the recommendations of the April 2013 National Academy of Sciences (NAS) report. EPA will address concerns specific to atrazine in connection with the development of its registration review decision for atrazine.

The NAS report, available at http://www.nap.edu/catalog.php?record_id=18344, outlines recommendations on specific scientific and technical issues related to the development of5

pesticide risk assessments that are compliant with the Endangered Species Act an d the Federal Insecticide, Fungicide, and Rodenticide Act. In November, the EPA, along with the U.S. Fish & Wildlife Service (USFWS), the National Marine Fisheries Service (NMFS) (collectively, the Services), and the U.S. Department of Agriculture (USDA), released a summary of their joint Interim Approaches for assessing risks to listed species from pesticides. The Interim Approaches were developed jointly by the Agencies in response to the NAS’ recommendations and reflect a common approach to risk asse ssment shared by the Agencies as a way of addressing scientific differences between EPA and the Services. The joint Interim Approaches were released prior to the stakeholder workshop held on November 15, 2013. EPA is presenting the joint Interim Approache s at the December 2013 PPDC and SFIREG meetings, allowing additional opportunities for stakeholders to comment on the Interim Approaches. The Agencies will consider public comments on the Interim Approaches prior to implementing them. The Agencies intend to jointly implement these approaches as part of a phased iterative process. EPA will refine its listed species risk assessments based on these interim approaches. The details of the joint Interim Approaches are contained in the white paper “Interim Ap proaches for National

- Level Pesticide Endangered Species Act Assessments Based on the Recommendations of the National Academy of Sciences April 2013 Report,” dated November 1, 2013, available at http:// www.epa.gov/espp/2013/nas.html

.
Regarding the C enter for B iological D iversity ’s request for EPA to begin informal consultation with the Services immediately after the workplan for atrazine is finalized, EPA plans to follow the March 2013 stakeholder engag ement paper (“Enhancing Stakeholder Input in the Pesticide Registration Review and ESA Consultation Processes and Development of Economically and Technologically Feasible Reasonable and Prudent Alternatives”) to identify the appropriate time for initiation of consultation, either formal or informal, with the Services. The stakeholder engagement paper, jointly developed by the EPA, USDA, and the Services and available at http://www.regulations.gov/#!documentDetail;D=EPA

- HQ

- OPP

- 2012

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- 0038, allows for

ear ly interaction with the Services under informal consultation. EPA and the Services acknowledge that early interaction as part of informal consultation may result in refinements to EPA’s effects determinations that can improve the efficiency of the ESA com pliance process. For example, EPA may involve the Services at the earliest stages of registration review. In general, EPA plans to initiate formal ESA consultation, if necessary, at the final decision stage in the registration review process. Consulting later in the process allows the EPA to develop more refined ecological risk assessments and to engage stakeholders in discussions that should result in more focused consultation packages that may include risk mitigation for listed species.6 Literature Ci ted

Chen, Wenlin and, Paul Mosquin, Impact of Alternative Monitoring Frequencies on Estimation of Atrazine Rolling Average Environmental Concentrations. Addendum to MRID 48550601. Final Report Addendum 2. May 29, 2012.

Chen, Wenlin, Paul Mosquin, and Cl int Truman. 2013. Sampling Bias Factors: Compensation for “Missing the Peak”. CropLife America RISE Spring Conference. Washington, DC.

Harrell, F.E. Jr. 2001. Regression Modeling Strategies. Springer. New York

Giddings, J.M. 2012. Atrazine: Review of Mesocosm and Microcosm Studies. Project Report Number: 12709. Compliance Services International (CSI).

Mosquin, Paul, Roy Whitmore, and Wenlin Chen. 2012. Estimation of Upper Centile Concentrations Using Historical Atrazine Monitoring Data from Community Water Systems. J. Environmental Quality. 41:834

- 844.

Mosquin, Paul, Roy Whitmore, and Wenlin Chen. Impact of Alternative Monitoring Frequencies on Estimation of Atrazine Rolling Average Environmental Concentrations. Report No. TK00380 02, Task No. : TK0038002. April 29, 2011a.

Mosquin, Paul, Roy Whitmore, and Wenlin Chen. Impact of Alternative Monitoring Frequencies on Estimation of Atrazine Rolling Average Environmental Concentrations. Addendum to MRID 48470008. Report No. TK0038002 , Task No. : TK0038002. Final Report Addendum. July 19, 2011b.

U.S. Environmental Protection Agency (USEPA). 2012. Problem Formulation for the Environmental Fate and Ecological Risk Assessment for Atrazine. White Paper for the FIFRA Scientific Advisory Panel, June 12

- 14, 2012.

U.S. Environmental Protection Agency (USEPA). 2013. Addendum to the Problem Formulation for the Ecological Risk Assessment to be Conducted for the Registration Review of Atrazine.