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OFFICE OF CHEMICAL SAFETY

AND POLLUTION PREVENTION

UNITED STATES ENVIRONMENTAL PROTECTION AGENCY

WASHINGTON, D.C. 20460

October 5, 2015

 PC Code: 028201

MEMORANDUM DP Barcode: 429136

SUBJECT: Propanil: EFED Response to Public Comments Regarding the Registration 

Review Problem Formulation: Docket ID# EPA-HQ-OPP-2015-0052.

FROM: Ryan Mroz, Biologist

He Zhong, Ph.D., Biologist

Environmental Risk Branch I

Environmental Fate and Effects Division (7507P)

THRU: Sujatha Sankula, Ph.D., Branch Chief

Greg Orrick, Risk Assessment Process Leader

Environmental Risk Branch I

Environmental Fate and Effects Division (7507P)

TO: Leigh Rimmer, Chemical Review Manager

Cathryn Britton, Team Leader

Kevin Costello, Branch Chief

Risk Management and Implementation Branch II

Pesticide Re-evaluation Division (7508P)

Attached please find the Environmental Fate and Effects Division (EFED)’s response to public comments 

on the problem formulation for the registration review of propanil (Docket ID No.: EPA-HQ-OPP-2015-

0052). Comments were received from the following stakeholders and are addressed in this response:

• RiceCo, LLC (RCLLC) – The Principal Registrant of propanil

• California Rice Commission (CRC)

• City of Sacramento Department of Utilities (CSDU)

• USA Rice Federation (USARF)

• Center for Biological Diversity (CBD)

EFED generally uses an outline format to address the comments (comment followed by EFED response). 

The names of the submitters are abbreviated for ease of reference (see above). Some comments are 

provided verbatim in italic font whereas others are summarized. Full comment documents can be found 

in the Docket.
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Response to Public Comments Regarding the Problem Formulation for the Registration Review of 

Propanil

1. Propanil’s importance, acreage treated, and usage data (CRC, RCLLC, USARF, and CSDU).

EFED Response: The Agency acknowledges the importance of propanil usage in rice production and 

appreciates the clarification of the use, usage and acreage treated. The information is helpful for the 

propanil Registration Review ecological risk assessment. Since the assessment is based on the label, 

the Agency is encouraging the registrant (RCLLC) to clarify all uses for other States in addition to 

California on the labels, especially the maximum single application rate (lbs a.i./acre), the maximum 

number of applications per year, the minimum re-application interval and the maximum annual 

application rate (lbs a.i./acre/year). 

2. The additional data needs for pollinators (USARF, CRC, and RCLLC).

USARF: Rice is a self-pollinating crop. Bees and other pollinators are not a fixture in rice fields. As 

such, USA Rice believes that EPA’s workplan calling for several honey bee and nectar toxicity studies is 

unnecessary and would tie up resources better used on other data gathering.

CRC: Impacts on honeybees are not an issue from rice farming practices. The registrant has the ability 

to comply with the data requirements, while our role is to provide information to assist with the final 

decision. Rice is a self-pollinated crop, it is not a cross pollinated crop like maize, and does not rely wind 

or insects for pollination. Pollen shed and pollination occurs right before, or as, the flower opens in the 

mid-morning hours. The flowers open for a short period, the anthers dehisce, and then flowers close, 

leaving the anthers outside the flower. Flowering and pollination usually takes place in mid-July through 

mid-August in California. This is not the period when managed bees under contract pollination are 

pollinating crops such as almonds during late winter to early spring

RCLLC: Propanil exhibits very low toxicity in honey bees. The EPA categorizes pesticides as "toxic to 

bees" if they cause greater than 50% mortality in adult bees exposed up to 11 micrograms per bee, which 

technically speaking means that the LD5o is less than 11 micrograms/bee. Available data indicate that 

the contact LD50 for Propanil is greater than 100 micrograms/bee and the oral LD50 for Propanil is 

greater than 94 micrograms/bee. Similarly, the contact LD50 for 3,4-DCA is greater than 100 

micrograms/bee and the oral LD50 is greater than 1,600 micrograms/bee. Additionally, it is believed that 

there have not been any adverse incidents involving Propanil and bees. EPA collects reports of toxicity 

incidents involving honey bees from the public, state regulatory agencies and from the adverse effects 

reporting obligations of registrants of pesticides. RiceCo believes that in the entire history of the use of 

Propanil on millions of rice acres in the United States for over 5 decades there has not been a reported 

adverse incident involving bees. That is consistent with the recent report by the USDA (Attractiveness of 

Agricultural Crops to Pollinating Bees for the Collection of Nectar and/or Pollen, 2015, USDA at p.18) 

confirming that rice is not attractive to pollinating bees. That is to be expected because when Propanil is 

applied, there are no flowers to attract bees.

EFED Response: The Agency has recently implemented the Pollinator Risk Assessment 

Framework1

. Honey bees are also used as a surrogate species for all terrestrial invertebrates including

Apis and non-Apis bees and other insect pollinators. The Agency evaluates multiple lines of evidence 

in determining which data to be used to inform the various tiers of refinement that may be required to 

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http://www2.epa.gov/sites/production/files/2014-06/documents/pollinator_risk_assessment_guidance_06_19_14.pdf
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support risk management decisions. Currently, the only data available to assess the potential risk from 

propanil to bees is an acute contact study with a non-definitive endpoint. Although honeybees may 

not be a fixture in rice fields, exposure to other insect pollinators adjacent to rice fields is possible 

from propanil usage. In addition, propanil toxicity against other life stages of the pollinator is

unknown. Therefore, additional pollinator studies are necessary. 

3. Monitoring data and model usages (CSDU and CRC). 

CSDU: In recent years, surface water monitoring programs in our region have detected propanil and its 

degradate 3,4-dichloroaniline (3,4-DCA) in the Sacramento River, both upstream and in the very reach 

that includes water treatment plant intakes. Both propanil and a major degradate - 3,4-dichloroaniline 

(3,4-DCA) - have been detected in the Sacramento River watershed on more than 100 occasions at 

concentrations up to 47 1Jg/L. Recent monitoring by the USGS on the Sacramento River at Freeport 

showed that 3,4-DCA was detected in nearly every sample, that propanil degradation is likely the source 

of most 3,4-DCA in the watershed, and that concentrations of the degradate were often three or more 

times the concentration of propanil. 

We understand that EPA is developing an update to the model it uses to estimate surface water 

concentrations of rice pesticides, the Pesticides in Flooded Agriculture Model (PFAM). We encourage 

EPA to use the updated version of PFAM in its propanil risk assessments if possible. Whether or not the 

updated version of PFAM is ready for use for this risk assessment, EPA should draw on the more detailed 

scientific understanding of the relationship between rice pesticide use and downstream drinking water 

intakes that it has gained through the PFAM update effort.

Since propanil monitoring is ongoing in our region, when EPA initiates work on its risk assessment, we 

request that EPA obtain the most recent California monitoring data from the California Water Board 

CEDEN database, California Department of Pesticide Regulations' Surface Water Monitoring database, 

and the U.S. Geological Survey National Water-Quality Assessment Program database. These databases 

will probably contain the data we mentioned above. (We understand that EPA routinely downloads data 

from these three government databases.). We request that EPA also contact the California Central Valley 

Regional Water Quality Control Board's Irrigated Lands Program, which may have additional data that 

have not yet been uploaded into CEDEN.

CRC: The California rice industry has a long history of managing water quality programs dating back 

over 30 years. The California Department of Pesticide Regulation (CDPR) monitored propanil in surface 

water during 1987, 1988, 1998 and 2001. Starting in 2003, all agriculture in the Central Valley began 

surface water monitoring under a conditional program to evaluate discharges from irrigated lands. The 

conditional program has evolved to permanent regulation implemented through waste discharge 

requirements with orders approved in 2014. Under the conditional program, the CRC monitored propanil 

at our established core sites and one river location patterning the monitoring after the thiobencarb 

schedule. Propanil monitoring took place from 2006 to 2008 using the EPA 8081A(w) method with the 

reporting limit of 0.05 μg/L...The CRC has resumed propanil monitoring as regular rotation under the 

current waste discharge requirements in 2015.

EFED Response: The Agency appreciates the data and resources provided by the commentators. The 

Agency will use the most recent aquatic models, such as PFAM, SWCC and PRZM-GW and review 

all available monitoring data collected by federal and state agencies such as the U.S. Geological 

Survey (USGS), National Water Quality Assessment (NAWQA) Data Warehouse and California 

Environmental Data Exchange Network (CEDEN) for propanil and its degradate 3,4-DCA for the 

Registration Review ecological risk assessment and drinking water assessment. 
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4. Consultation with the Services (CBD). 

CBD: “EPA has an independent duty under the Endangered Species Act to consult with the U.S. Fish and 

Wildlife Service and National Marine Fisheries Service on the [Registration Review] of propanil” and its 

end-use product labels including making “defensible “Not Likely to Adversely Affect” and “Likely to 

Adversely Affect” determinations as a prerequisite for defensible “Jeopardy” and “No Jeopardy” 

determinations,” assessing the “adverse impacts of propanil in critical habitat,” and following the new 

Interim Approaches based on recommendations of the National Academy of Science that include a spatial 

analysis at Step 1 and geographic restrictions on product labels to protect critical habitat at Steps 2 and 3.

EFED Response: EPA has reviewed the comments from CBD on the problem formulation for the 

registration review of propanil and plans to address many of the concerns raised by CBD 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 propanil in connection with the development of its registration review decision 

for propanil.

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 of pesticide 

risk assessments that are compliant with the Endangered Species Act and 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 

assessment 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 presented the joint Interim Approaches at the December 2013 PPDC and 

SFIREG meetings, allowing additional opportunities for stakeholders to comment on the Interim 

Approaches. The Agencies are considering 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 

Approaches for National-Level Pesticide Endangered Species Act Assessments Based on the 

Recommendations of the National Academy of Sciences April 2013 Report,” dated November 1, 

2013, available at http://www.epa.gov/espp/2013/nas.html.

EPA plans to follow the March 2013 stakeholder engagement 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-2012-0442-0038, allows for early 

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 compliance 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 
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and to engage stakeholders in discussions that should result in more focused consultation packages 

that may include risk mitigation for listed species.