Docket Number; EPA–HQ–OPP–2009–0618 

www.regulations.gov 

 

United States Prevention, Pesticides March 2010 

Environmental Protection and Toxic Substances 

Agency (7510P)

10,10'-Oxybisphenoxarsine (OBPA) 

Final Work Plan 

Registration Review March 2010 

Docket Number; EPA-HQ-OPP-2009-0618 

www.regulations.gov 

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TABLE OF CONTENTS

OBPA Registration Review Team Members.............................................. 4 

I. Introduction.................................................................................... 5 

II. Comments on Preliminary Work Plan................................................. 5 

III. Risk Assessment and Data Needs...................................................... 6 

IV. Timeline...................................................................................... 9 

V. Glossary of Terms and Abbreviations.................................................. 10 
Docket Number; EPA-HQ-OPP-2009-0618 

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10,10'-Oxybisphenoxarsine (OBPA) Registration Review Team

Human Health & Environmental Effects 

Tim McMahon 

Najm Shamim 

Risk Management

Monisha Harris 

Lance Wormell 

Office of General Counsel

Philip Ross 
Docket Number; EPA-HQ-OPP-2009-0618 

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I. Introduction

This is EPA’s Final Work Plan (FWP) for the registration review of OBPA. The 

work plan includes the expected registration review timeline. The work plan also 

addresses public comments received concerning the Preliminary Work Plan (PWP) in the 

Summary Document which was posted in the OBPA registration review docket, 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 pursuant to Section 

3(g) of the Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA) and will review 

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

FIFRA standard for registration. The Agency will consider benefits information and data 

as required by FIFRA. Changes in science, public policy and pesticide use practices will 

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/. 

 The OBPA Preliminary Work Plan was published September 23, 2009. The 90-day 

comment period ended on December 22, 2009. The Preliminary Work Plan document is 

available on www.regulations.gov, docket number EPA-HQ-OPP-2009-0618. 

 

II. Comments Received on Preliminary Work Plan: 

 EPA received one comment during the public comment period on the initial 

docket, described below. 

In the PWP, EPA also 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 EPA received one comment as described 

and discussed below. The comment received during the initial public comment period 

did not affect the data needs, work plan and timeline described in the PWP and they 

remain as they were presented initially in the PWP. Further, this document makes final 

the work plan for the OBPA registration review process. 

Comment: The FIFRA Endangered Species Task Force (FESTF) submitted a comment 

requesting that any technical registrant for OBPA who is not a member of the FESTF (or 

a company having met its data compensation obligations) be asked to provide a formal 

offer-to-pay to FESTF for reliance on their data. In their comment, FESTF also noted 

that Akcros Chemicals, Inc., Rohm and Hass Company and Troy Chemical Company are 

the leading registrant for OBPA, and that the above mentioned are not FESTF members. 
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Therefore, the technical registrant must offer to pay FESTF to rely on FESTF submitted 

data or develop substantial similar data on their own.

Response: The Agency thanks FESTF for its comment and will consider this 

information as it conducts the registration review and makes its registration 

review decisions. 

III. Risk Assessment and Data Needs

A Reregistration Eligibility Decision was completed for OBPA in June 1993. 

However, to complete registration review, additional data are needed to conduct the 

human health and ecological risk assessments. 

Human Health Risk 

The Agency reviewed the hazard and exposure databases for OBPA as part of this 

registration review case. As a result of this review, EPA anticipates that additional 

toxicity and exposure data will be needed to complete registration review. Toxicology 

data are needed to address subchronic, developmental, and reproductive toxicity as well 

as mutagenic potential. In addition, metabolism data are needed to characterize the 

disposition and biotransformation of OBPA in vivo. 

EPA believes risk assessments are needed to ensure that the OBPA registration review 

case meets the safety standards established by FFDCA, as amended by FQPA. The 

Agency intends to complete the human health risk assessments presented below. Further 

information and detailed justifications for the required studies are available in the 

document titled “10,10’ Oxybisphenoxarsine (OBPA): Human Health Assessment 

Scoping Document in Support of Registration Review” (dated August 20, 2009). 

• Residential risk assessment (adults and children) following use/application of 

products made from preserved materials (e.g., pool liners, vinyl flooring, and 

mattress covers). 

• Occupational handler inhalation risk assessment to estimate potential risks 

associated with mixing/loading and handling OBPA during manufacture of 

plastics or technical and formulated products containing OBPA. 

• An aggregate exposure and risk assessment may be needed for OBPA 

depending on the submission and review of any toxicology studies required 

for OBPA and the formal evaluation of routes and magnitude of anticipated 

human exposures. 

Dietary and Drinking Water Assessment

The Agency does not expect any direct or indirect dietary exposure to occur from 

the current use patterns for OBPA products; therefore, EPA does not anticipate 

conducting a dietary and drinking water risk assessment. 
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Occupational and Residential Assessment

Because currently registered uses of OBPA may result in both residential and 

occupational exposure, the Agency will conduct a residential risk assessment and an 

occupational risk assessment. Plastics containing OBPA (e.g., polyvinylchloride, 

polyurethane, and ethylene-vinylacetate copolymer plastics) are fabricated into numerous 

items – including shower curtains, floor coverings, carpets, ditch liners, coated fabrics 

(including mattress covers), marine upholstery, tarpaulins, gaskets, weather stripping, 

shoe soles, and swimming pool liners – that may result in residential and/or occupational 

exposure. 

Anticipated Human Health Data Needs 

The review of the existing toxicological database for OBPA showed that many of 

the studies have significant deficiencies that do not allow adequate characterization of 

hazard, and that other studies are not available that would be required to adequately 

characterize risk for OBPA based on current use patterns. Therefore, for the purposes of 

registration review, anticipated toxicology data needs for OBPA are as follows: 

 

Anticipated OBPA Human Health Toxicity Data Needs: 

• (GLN 870.1300) Acute Inhalation Toxicity-rodent 

• (GLN 870.3100) 90-Day Oral Toxicity-rodent 

• (GLN 870.3250) 21-Day Dermal Toxicity-rodent 

• (GLN 870.3700) Developmental Toxicity- rodent 

• (GLN 870.3800) Reproductive Toxicity- rodent 

• (GLN 870.7485) General Metabolism-rodent* 

• (GLN 870.5265) Salmonella typhimurium reverse mutation assay 

• (GLN 870. 5300) Mammalian cells in culture 

• (GLN None) In vivo cytogenetics 

*With respect to the metabolism data requirements, a dual radiolabeled test substance would need to be 

tested. Specifically, the arsenic portion of the molecule would need to be labeled as well as the aromatic 

portion of the molecule to adequately determine metabolites and tissue distribution. 

Anticipated OBPA Occupational/Residential Exposure Data Needs 

• (GLN 875.1200) Dermal indoor exposure 

• (GLN 875.1400) Inhalation indoor exposure 

• (GLN 875.1600) Data reporting and calculations 

• (GLN 875.1700) Product use information 

• (GLN None) Leaching studies for pool liners, vinyl flooring, and mattress covers* 

*To properly assess exposure from pool liners, vinyl flooring, and mattress covers (which are 

representative of the highest exposures), the Agency expects to require leaching studies for each matrix. 

Since a guideline and associated protocol are not currently available, registrants likely will be required to 

submit a protocol to EPA for review prior to initiating the study. 
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Ecological Risk

The Agency reviewed the environmental fate and ecological hazard databases for 

OBPA. Based on its review, EPA believes risk assessments are needed to ensure that the 

OBPA registration review case meets the FIFRA standards. For OBPA, the Agency 

anticipates needing some of the environmental fate and ecological effects data 

requirements listed for OBPA in order to conduct the environmental fate and ecological 

risk assessments, including an endangered species assessment. Further information and 

detailed justifications for the studies that are expected to be required are available in the 

document titled “Summary of Product Chemistry, Environmental Fate, and Ecotoxicity 

Data for the 10,10'-Oxybisphenoxarsine Registration Review Decision Document” (dated 

August 10, 2008).

 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 OBPA’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 Services (the 

Services), as appropriate. 

Anticipated Environmental Fate and Ecological Data Needs

The Agency anticipates conducting environmental fate and ecological risk 

assessments for material preservatives that potentially pass through waste water treatment 

plants (WWTPs) and may be discharged into terrestrial and aquatic environments. 

Therefore, the Agency anticipates requiring the environmental fate and ecotoxicity data 

identified below for OBPA and/or any of its major degradation products that are of 

potential concern for all registered uses of OBPA. The following environmental fate and 

ecotoxicity data are needed to conduct an environmental fate and ecological risk 

assessment: 

 

Anticipated OBPA Environmental Fate Data Needs 

• (GLN 835.2120) Hydrolysis 

• (GLN 835.2240) Photodegradation in water 

• (GLN 850.6800) Modified activated sludge respiration inhibition 

• (GLN 835.1110) Activated sludge sorption isotherm 

• (GLN 835.3110) Ready biodegradability 

• (GLN None) Leachability of OBPA from polyvinyl chloride (PVC) swimming 

pool liner and a film of vinyl baby pants* 

* Since a guideline and associated protocol are not currently available, registrants likely will be required to 

submit a protocol to EPA for review prior to initiating the study. 
Docket Number; EPA-HQ-OPP-2009-0618 

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Anticipated OBPA Ecological Data Needs 

• (GLNs 850.4400 & 850.5400) algal toxicity (Tier II) using freshwater green alga, 

Selenastrum capricornutum 

Product Chemistry Status and Anticipated Data Needs 

All product chemistry data requirements have been satisfied for the active 

ingredient OBPA. Therefore, the Agency does not anticipate the need to require 

additional product chemistry data for OBPA at this time. 

IV. Timeline

EPA has created the following estimated timeline for the completion of the OBPA 

registration review case. 

 

Anticipated Schedule 

Activities Estimated Month/Year 

Phase 1: Opening the docket 

Open Public Comment Period for OBPA Docket Completed September 2009

Close Public Comment Period Completed December 2009

Phase 2: Case Development 

Develop Final Work Plan (FWP) March 2010 

Issue DCI March 2011 

Data Submission March 2013 

Open Public Comment Period for Preliminary Risk Assessments September 2014 

Close Public Comment Period December 2014 

Phase 3: Registration Review Decision 

Open Public Comment Period for Proposed Reg. Review Decision March 2015 

Close Public Comment Period June 2015 

Final Decision and Begin Post-Decision Follow-up 2015 

Total (years) 6 

Next Steps

The Agency plans to develop a Data Call-In for this pesticide and expects to issue it in 

December 2011. 
Docket Number; EPA-HQ-OPP-2009-0618 

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III. GLOSSARY of TERMS & ABBREVIATIONS

ai Active Ingredient 

AR Anticipated Residue 

ASTM American Society for Testing and Materials 

AWPA American Wood Preserver’s Association 

CBI Confidential Business Information 

CFR Code of Federal Regulations 

cPAD Chronic Population Adjusted Dose 

CSF Confidential Statement of Formula 

CSFII USDA Continuing Surveys for Food Intake by Individuals 

DCI Data Call-In 

DEEM Dietary Exposure Evaluation Model 

DFR Dislodgeable Foliar Residue 

DNT Developmental Neurotoxicity 

DWLOC Drinking Water Level of Comparison 

EC Emulsifiable Concentrate Formulation 

EDWC Estimated Drinking Water Concentration 

EEC Estimated Environmental Concentration 

EP End use Product 

EPA Environmental Protection Agency 

EUP End-Use Product 

FDA Food and Drug Administration 

FIFRA Federal Insecticide, Fungicide, and Rodenticide Act 

FFDCA Federal Food, Drug, and Cosmetic Act 

FQPA Food Quality Protection Act 

FOB Functional Observation Battery 

GENEEC Tier I Surface Water Computer Model 

IR Index Reservoir 

LC50 Median Lethal Concentration. A statistically derived concentration of a 

substance that can be expected to cause death in 50% of test animals. It is 

usually expressed as the weight of substance per weight or volume of water, air 

or feed, e.g., mg/l, mg/kg or ppm. 

LD50 Median Lethal Dose. A statistically derived single dose that can be expected to 

cause death in 50% of the test animals when administered by the route indicated 

(oral, dermal, inhalation). It is expressed as a weight of substance per unit 

weight of animal, e.g., mg/kg. 

LOC Level of Concern 

LOAEL Lowest Observed Adverse Effect Level 

μg/g Micrograms Per Gram 

μg/L Micrograms Per Liter 

mg/kg/day Milligram Per Kilogram Per Day 

mg/L Milligrams Per Liter 

MOE Margin of Exposure 

MRID Master Record Identification (number). EPA's system of recording and tracking 

submitted studies. 

MUP Manufacturing-Use Product 

NA Not Applicable 

NAWQA USGS National Ambient Water Quality Assessment 

NPDES National Pollutant Discharge Elimination System 

NR Not Required 

NOAEL No Observed Adverse Effect Level 

OPP EPA Office of Pesticide Programs 

OPPTS EPA Office of Prevention, Pesticides and Toxic Substances 

PAD Population Adjusted Dose 
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PAIRA Pure Active Ingredient Radiolabelled 

PCA Percent Crop Area 

PDP USDA Pesticide Data Program 

PHED Pesticide Handler's Exposure Data 

PHI Preharvest Interval 

phr Pounds Per Hundred 

ppb Parts Per Billion 

PPE Personal Protective Equipment 

ppm Parts Per Million 

PRZM/EXAMS Tier II Surface Water Computer Model 

Q1* The Carcinogenic Potential of a Compound, Quantified by the EPA's Cancer 

Risk Model 

RAC Raw Agriculture Commodity 

RED Reregistration Eligibility Decision 

REI Restricted Entry Interval 

RfD Reference Dose 

RQ Risk Quotient 

RTU Ready to Use 

SCI-GROW Tier I Ground Water Computer Model 

SAP Science Advisory Panel 

SF Safety Factor 

SLN Special Local Need (Registrations Under Section 24©) of FIFRA) 

TGAI Technical Grade Active Ingredient 

TEP Typical End-Use Product 

USDA United States Department of Agriculture 

UF Uncertainty Factor 

WPS Worker Protection Standard