Introduction

This is the Environmental Protection Agency’s (EPA or the Agency) Final Work Plan

(FWP) for the registration review of bentazon. The Final Work Plan includes the expected 

registration review timeline. The FWP also addresses public comments received concerning the 

Preliminary Work Plan (PWP) in the Summary Document which was posted in the bentazon 

registration review docket (EPA-HQ-OPP-2010-0117) and any other comments concerning the 

initial docket postings. The Summary Document provided information on what EPA knows 

about the pesticide and what additional risk analyses and data or information the Agency 

believes are needed to make a registration review decision. 

The Agency is implementing the registration review program and will review each 

registered pesticide every 15 years to determine whether it continues to meet the Federal 

Insecticide, Fungicide, and Rodenticide Act (FIFRA) standard for registration. Changes in 

science, public policy, and pesticide use practices occur over time. The registration review 

program is intended to make sure that, as the ability to assess risk evolves and as policies and 

practices change, all registered pesticides continue to meet that statutory standard. The public 

phase of registration review begins when the initial docket is opened for each case. Information 

on this program is provided at http://www.epa.gov/oppsrrd1/registration_review/. 

Bentazon is a benzothiadiazole herbicide registered to control post-emergent broadleaf 

weeds and sedges in numerous agricultural field crops, and around trees and vines in various 

fruit and nut crops. Bentazon is also registered for use to control weeds in residential and 

recreational lawns around ornamental plants. The Reregistration Eligibility Decision (RED) for 

bentazon was completed in September 1994 (available at: 

http://www.epa.gov/oppsrrd1/REDs/0182.pdf). In 2000, EPA reassessed tolerances of bentazon 

in compliance with the Food Quality Protection Act (FQPA) (65 Fed. Reg. 12122, March 8, 

2000). 

This document makes final the work plan for the bentazon registration review processes. 

Actions since Publication of PWP

In 2005, EPA received new use applications for bentazon for peaches and nectarines from 

Interregional Research Project No. 4 (IR-4). A dietary risk assessment was completed in 2006 

that evaluated the proposed new uses and updated drinking water exposure estimates for 

registered uses of bentazon. This risk assessment showed that the existing uses of bentazon 

result in chronic dietary risk estimates of concern for infants. Most of the dietary bentazon 

exposure to infants is from drinking water. IR-4 subsequently withdrew the new use requests. 

To address the dietary risks of concern for the existing uses of bentazon, the technical registrant 

(BASF) has voluntarily requested to amend their product registration label to clarify that the 

maximum annual application rate is 2 lbs of bentazon active ingredient (ai) from all sources per 

acre per calendar year and not 3 lbs ai/Acre/year. This rate reduction mitigates the dietary risks 

of concern identified in the 2006 dietary risk assessment. On September 21, 2010 BASF sent a 

formal correspondence to EPA, committing to submit a label amendment request to clarify the 

lower maximum annual application rate. 
In May 2010, BASF submitted a letter voluntarily requesting the cancellation of the 

following five bentazon Section 3 product registrations: 7969-78, 7969-122, 51036-363, 51036-

415, and 51036-421. On September 22, 2010, a Federal Register Notice (FRN) announcing the 

receipt of the registrants request to voluntarily cancel certain bentazon pesticide registrations was 

published. This notice initiated a 30-day comment period. These requests will not terminate any 

use sites of bentazon. EPA intends to grant these requests at the close of the comment period for 

this announcement unless the Agency receives substantive comments within the comment period 

that would merit its further review of the requests, or unless the registrants withdraw their 

requests within this period. 

Comments Received on Preliminary Work Plan 

 On March 31, 2010 EPA opened a 60-day public comment period for the registration 

review of bentazon. The comment period ended on June 1, 2010. The Preliminary Work Plan 

document can be located in the bentazon registration review docket (EPA-HQ-OPP-2010-0117) 

at www.regulations.gov. 

 In the PWP, EPA solicited comments on three specific topics: environmental justice, 

water body impairment and trade irritants. No comments or information were received during 

the public comment period concerning these issues.

During the public comment period, the Agency received several comments, as described 

and discussed below, from two parties (BASF and the Physicians Committee for Responsible 

Medicine). The comments received do not change the data and risk assessment needs or the 

timeline detailed in the bentazon PWP. 

In their comments, the technical registrant identified several application use patterns and 

crop uses which they claim are not supported by BASF and asked the Agency to “adjust their 

assessments to eliminate these from the work plan.” The Agency thanks the registrant for their 

comments and will consider this information when conducting the risk assessments. 

BASF also commented that “EPA has misinterpreted the label directions and use rates 

specified on the Rezult ® Herbicide Label (EPA Reg. No. 7969-194) as 3.2 pints/A (2 lb 

ai/Acre), when the correct use rate is 1.6 pints /Acre of the bentazon component of Rezult, 

resulting in a bentazon use rate of only 1.0 lb ai/Acre from Rezult application.” The Agency 

thanks BASF for their comment; however EPA believes that the current label indicates a 

maximum annual application rate of 3 lbs ai/Acre. In response, the registrant has voluntarily 

requested to amend their product registration label to clarify that the maximum annual 

application rate is 2 lbs ai/Acre and not 3 lbs ai/Acre. This rate reduction label amendment 

mitigates the dietary risks of concern identified in the 2006 dietary risk assessment. 

 The Agency also received several comments from BASF and the Physicians Committee 

for Responsible Medicine (PCRM) regarding the technical information presented in the 

Registration Review – Preliminary Problem Formulation for Ecological Risk and Environmental 

Fate, Endangered Species, and Drinking Water Assessments for Sodium Bentazon document,

dated February 5, 2010. A detailed description of the comments received and the Agency’s 
response to these comments is available in a separate response memoranda from the Agency’s 

Environmental Fate and Effects Division (EFED), which can be located in the bentazon 

registration review docket (EPA-HQ-OPP-2010-0117) at www.regulations.gov. 

Anticipated Risk Assessment and Data Needs

The Agency anticipates conducting a comprehensive ecological risk assessment, 

including an endangered species risk assessment, for all uses of bentazon. The Agency also 

anticipates revising dietary, residential, aggregate, and occupational risk assessments for all uses 

of bentazon. 

Ecological Risk: 

• The most recent ecological risk assessment was completed in 2005 to support the proposed 

new use of bentazon to control weeds in peach and nectarine orchards. 

• In a refined risk assessment for the 1994 RED, EPA concluded that registered uses of 

bentazon would “not likely adversely affect” threatened and endangered mammals and 

birds. However, this assessment was not conducted pursuant to current policies. 

Accordingly, the Agency has not conducted a risk assessment that supports a complete 

endangered species determination. The ecological risk assessment planned during 

registration review will allow the Agency to determine whether bentazon’s use has “no 

effect” or “may affect” federally listed threatened or endangered species (listed species) or 

their designated critical habitats. When an assessment concludes that a pesticide’s use “may 

affect” a listed species or its designated critical habitat, the Agency will consult with the 

U.S. Fish and Wildlife Service and/or National Marine Fisheries Service (the Services), as 

appropriate. 

• The Agency needs the following data in order to conduct a complete ecological risk 

assessment, including an endangered species assessment, for bentazon: 

o GDLN 850.1300 – Aquatic Invertebrate Life Cycle (freshwater) 

o GDLN 850.1400 – Fish Early Life-Stage (freshwater) 

o GDLN 850.2100 – Avian Acute Oral Toxicity, Passerine 

o GDLN 850.5400 – Aquatic Plant Growth (algal) (Tier II) 

o GDLN 835.6100 (7) – Environmental Chemistry Methods – soil 

o GDLN 835.6200 (7) – Environmental Chemistry Methods – sediment 

• For a detailed discussion of the ecological risk assessment and data needs refer to the 

Registration Review – Preliminary Problem Formulation for Ecological Risk and 

Environmental Fate, Endangered Species, and Drinking water Assessments for Sodium 

Bentazon (PC Code 103901) (February 5, 2010), which is available in the docket. 
Human Health Risk: 

• The most recent human health risk assessment for bentazon was completed in 2006 to 

support the proposed new use of bentazon to control weeds in peach and nectarine 

orchards. 

• The bentazon toxicity database is not complete. EPA needs the following guideline studies 

to reevaluate toxicological endpoints for bentazon: 

o GDLN 870.7800 – Immunotoxicity 

o GDLN 870.6200 – Acute Neurotoxicity – Rat 

o GDLN 870.6200 – 90-day Neurotoxicity – Rat 

• The bentazon residue chemistry database is sufficient to support all current bentazon 

registrations. 

• The Agency anticipates conducting a complete dietary risk assessment, which includes a 

refined drinking water assessment, in registration review to incorporate updated estimated 

drinking water concentrations, updated percent crop treated information, and potential 

changes to toxicological endpoints and safety factors. 

• The Agency anticipates revising the bentazon residential risk assessment in registration 

review. A higher application rate (application by commercial applicators only) is 

registered for use on residential lawns and has not been assessed for post-application 

exposure. In addition, updated transfer coefficients are available for the post-application 

dermal assessment. Lastly, a golfer post-application assessment will need to be conducted 

as part of registration review. 

• The Agency anticipates revising the aggregate risk assessment in registration review to 

incorporate revised residential and dietary assessments as well as any new toxicological 

endpoints and safety factors. 

• The Agency anticipates revising the occupational risk assessment in registration review to 

incorporate revised toxicological endpoints and several handler and post-application 

exposure scenarios that have not been previously assessed. 

• For a detailed discussion of the human health risk assessment and data needs refer to the 

Bentazon. Human Health Assessment Scoping Document in Support of Registration Review 

(March 17, 2010), which is available in the docket. 

Other Data Needs: 

• GLDN 830.7050 UV/Visible Light Absorption – this study is a new data requirement under 

40 CFR part 158 (Product Chemistry Data Requirements) for registration of a pesticide 

(food and non-food uses). The Agency anticipates requiring this study to obtain basic 
information about the compound’s identity/composition and the wavelengths at which the 

compound may be susceptible to photochemical degradation. 

Endocrine Disruptor Screening Program

As required under FFDCA section 408(p), EPA has developed the Endocrine Disruptor 

Screening Program (EDSP) to determine whether certain substances (including pesticide active 

and other ingredients) may have an effect in humans or wildlife similar to an effect produced by 

a “naturally occurring estrogen, or other such endocrine effects as the Administrator may 

designate.” The EDSP employs a two-tiered approach to making the statutorily required 

determinations. Tier 1 consists of a battery of 11 screening assays to identify the potential of a 

chemical substance to interact with the estrogen, androgen, or thyroid (E, A, or T) hormonal 

systems. Chemicals that go through Tier 1 screening and are found to have the potential to 

interact with E, A, or T hormonal systems will proceed to the next stage of the EDSP where EPA 

will determine which, if any, of the Tier 2 tests are necessary based on the available data. Tier 2 

testing is designed to identify any adverse endocrine related effects caused by the substance, and 

establish a quantitative relationship between the dose and the E, A, or T effect. 

Between October 2009 and February 2010, EPA issued test orders/data call-ins for the 

first group of 67 chemicals, which contains 58 pesticide active ingredients and 9 inert 

ingredients. This list of chemicals was selected based on the potential for human exposure 

through pathways such as food and water, residential activity, and certain post-application 

agricultural scenarios. This list should not be construed as a list of known or likely endocrine 

disruptors. 

Bentazon is not among the group of 58 pesticide active ingredients on the initial list to be 

screened under the EDSP. Under FFDCA sec. 408(p) the Agency must screen all pesticide 

chemicals. Accordingly, EPA anticipates issuing future EDSP orders/data call-ins for all 

Registration Review cases, including those for which EPA has already opened a Registration 

Review docket for a pesticide active ingredient. 

For further information on the status of the EDSP, the policies and procedures, the list of 

67 chemicals, the test guidelines and the Tier 1 screening battery, please visit our website: 

http://www.epa.gov/endo/. 
Timeline

The Agency has created the following estimated timeline for the completion of the 

bentazon registration review. 

Registration Review for Bentazon– Projected Registration Review Timeline 

Activities Estimated Date 

Opening the docket 

Open Docket and Public Comment Period 2010 – March

Close Public Comment 2010 – May

Case Development 

Final Work Plan 2010 – September

Issue DCI 2011 – April – June

Data Submission 2013 – April – June

Open Public Comment Period for Preliminary Risk Assessments 2014 – Oct. – Dec.

Close Public Comment Period 2015 – Jan. – March

Registration Review Decision 

Open Public Comment Period for Proposed Registration Review 

Decision

2015 – April - June 

Close Public Comment Period 2015 – July – Sept.

Final Registration Review Decision and Begin Post-Decision Follow-up 2016

Total (years) 6 

Next Steps

The Agency plans to issue a Data Call-In (DCI) for bentazon in 2011. This new data will 

be used to conduct the risk assessments outlined in this FWP for all bentazon uses.