Docket Number: EPA-HQ-OPP-2010-0215

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Fosamine Ammonium Final Work Plan

Registration Review

November 2010

Case No. 2355

Richard P. Keigwin, Jr.

Director, Pesticide Re-evaluation Division

Approved by:

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Date
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Fosamine Ammonium Final Work Plan 

Introduction:

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

registration review of fosamine ammonium. The FWP includes the expected registration review 

timeline. The FWP also addresses public comments received concerning the Preliminary Work 

Plan in the Summary Document, which was posted in the fosamine ammonium registration 

review docket (EPA-HQ-OPP-2010-0215), 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 new 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 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 the 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/. 

Fosamine ammonium is an herbicide registered for use on non-agricultural rights-of way, 

industrial sites, fencerows, pine plantations, and sewage disposal areas. Formulated as a water 

soluble liquid, fosamine ammonium functions as a plant growth regulator. There are no 

residential uses and no residential exposures from the registered uses are anticipated. Tolerances 

are not currently established for fosamine ammonium since there are no registered food or feed 

uses. Fosamine ammonium was first registered in 1975 and the reregistration eligibility decision 

(RED) was issued in 1995. 

Comments Received on Preliminary Work Plan

Comments on the fosamine ammonium PWP were submitted during the public comment period 

by the fosamine ammonium registrant E.I. DuPont de Nemours and Co., the FIFRA Endangered 

Species Task Force (FESTF), and the Physicians Committee for Responsible Medicine (PCRM). 

The 60-day public comment period on the fosamine ammonium PWP began on June 23, 2010 

and closed on August 23, 2010. These comments did not change the work plan or timeline 

established in the PWP. In addition, through 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 comment period concerning these topics. 

Risk Assessment and Data Needs:

Ecological Risk: 

• The most recent ecological risk assessment for fosamine ammonium was completed in 

1994 to support the RED. 
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• The Agency has not conducted a risk assessment that supports a complete endangered 

species determination for fosamine ammonium. The ecological risk assessment planned 

during registration review will allow the Agency to determine whether fosamine 

ammonium’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 will require the following data in order to conduct a complete ecological risk 

assessment, including an endangered species assessment, for fosamine ammonium: 

o GLN 850.2100 Avian acute oral toxicity study (passerine species) 

o GLN 850.1400 Fish early life-stage (freshwater) (Rainbow trout, Bluegill sunfish) 

o GLN 850.1300 Aquatic invertebrate life-cycle (freshwater) (Water flea) 

• Please refer to the document, Registration Review – Preliminary Problem Formulation 

for the Ecological Risk and Drinking Water Assessments for Fosamine Ammonium,

located in the docket for a detailed discussion of the anticipated risk assessment and data 

needs. 

Human Health Risk:

• The most recent human health risk assessment for fosamine ammonium was completed in 

1994 to support the RED. 

• A dietary (food only) exposure assessment is not anticipated for fosamine ammonium 

because there are no registered food or feed uses. However, a new drinking water 

exposure and risk assessment is anticipated for registration review. 

• Based on the registered uses, the Agency does not anticipate conducting a residential 

exposure assessment for this registration review of fosamine ammonium. 

• The Agency does not intend to conduct an aggregate risk assessment as there are no 

food/feed uses, and no residential uses of fosamine ammonium. 

• The most recent occupational exposure and risk assessments for fosamine ammonium 

were conducted in 1994 to support the RED. An updated occupational exposure and risk 

assessment, that incorporates updated assessment methodologies, will be conducted 

during this registration review. 

• The Agency will require the following data in order to support a human health risk 

assessment for fosamine ammonium: 

o GLN 870.3465 90-Day Inhalation Toxicity (rat) 

o GLN 870.3700b Developmental Toxicity (rabbit) 
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o GLN 870.7800 Immunotoxicity 

• Following the submission of the additional toxicological data, the Agency plans to update 

the human health toxicity profile. 

• Please refer to the document, Fosamine Ammonium. Human Health Assessment Scoping 

Document in Support of Registration Review, located in the docket for a detailed 

discussion of the anticipated risk assessment and data needs for human health. 

Other Anticipated Data Needs: 

• GLN 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. 

Timeline:

EPA has created the following estimated timeline for the completion of the fosamine ammonium 

registration review. This timeline has been shortened since the PWP to account for a shorter 

period between issuance of the DCI and data submission, since the Agency will not be requiring 

any studies that take more than one year to conduct. 

Registration Review for Fosamine Ammonium – Projected Registration Review Timeline

Activities Estimated Date 

Opening the docket 

Open Docket and Public Comment Period 2010 – June 

Close Public Comment 2010 – August 

Case Development 

Final Work Plan 2010 – November 

Issue Data Call-in (DCI) 2011 – July – Sept. 

Data Submission 2012 – July – Sept. 

Open Public Comment Period for Preliminary Risk Assessments 2014 – Jan. – March 

Close Public Comment Period 2014 – April - June 

Registration Review Decision 

Open Public Comment Period for Proposed Registration Review 

Decision 

 2014 – July - Sept. 

Close Public Comment Period 2014 – Oct. – Dec. 

Final Registration Review Decision and Begin Post-Decision Follow-up 2015 

Total (years) 5 
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Summary of Comments Received During Docket Opening:

The fosamine ammonium registration review docket was open for a 60-day public comment 

period which began on June 23, 2010 and closed on August 23, 2010. During that time, E.I. 

DuPont de Nemours and Co., the FIFRA Endangered Species Task Force (FESTF), and the 

Physicians Committee for Responsible Medicine (PCRM) submitted comments which are 

summarized below. The comments did not change the work plan or timeline set out in the 

preliminary work plan. Consequently, this document makes final the work plan for the fosamine 

ammonium registration review process. 

For a more detailed response regarding the comments, please see the memos in the docket, 

EFED Response to Comments on Preliminary Problem Formulation for Registration Review of 

Fosamine Ammonium (10/5/2010) and Fosamine Ammonium: Response to Comments on the 

Human Health Risk Scoping Document in Support of Registration Review. 

PCRM Comment:

The Physicians Committee for Responsible Medicine (PCRM) submitted a comment that it 

supports the use of newly revised OECD test guideline (TG 223) for acute avian oral toxicity 

testing (GLN 850.2100). 

Agency Response:

The Agency thanks PCRM for its comments. Currently, the Agency is awaiting completion of 

the validation process for OECD TG 223. Until validation is complete, studies using this 

guideline will not be classified. Therefore, at this time the Agency cannot say whether or not 

avian acute oral toxicity studies done under the new OECD test guidelines (TG 223), will be 

acceptable to meet the Agency's data requirements. 

FESTF Comment: 

The FIFRA Endangered Species Task Force (FESTF) submitted a comment informing the 

Agency that DuPont, the leading technical registrant for fosamine ammonium, is a FESTF 

member and therefore entitled to rely on FESTF data. 

Agency Response: 

The Agency thanks FESTF for its comment and will consider it as it conducts the registration 

review of fosamine ammonium. 

DuPont Comment: 

DuPont argued for the Agency to consider limiting the aquatic chronic toxicity testing to the 

invertebrate Daphnia magna instead of rainbow trout. 

Agency Response:

The Agency noted that 40 CFR Part 158.630 requires both Guideline 850.1300 (aquatic 

invertebrate life cycle) and 850.1400 (fish early-life stage) studies for all terrestrial, forestry and 

residential uses. In addition, available toxicity data for fosamine ammonium show the chemical 

to be more toxic to fish than to aquatic invertebrates. Finally the Agency noted that the lack of 

data (i.e. only one species test) will limit the flexibility the Agency and registrants have in 
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complying with the Endangered Species Act, which could result in restrictions for fosamine 

ammonium use that might prove to be unnecessary given data to address this area of uncertainty. 

 

DuPont Comment:

Based on the very low acute and chronic toxicity demonstrated in the mammalian and bird 

studies already conducted, the registrant believes that further testing on a passerine species is 

unwarranted. 

Agency Response:

Avian Acute Oral Toxicity Test (850.2100) data are required for one passerine species and either 

one waterfowl species or one upland game bird species for terrestrial, aquatic, forestry, and 

residential outdoor uses. The Agency noted that more than one species is required to avoid 

possible over- or under-estimation of risk and will allow for greater flexibility in compliance 

with the Endangered Species Act during the upcoming ecological assessment. 

DuPont Comment: 

DuPont noted several errors in the acute toxicity categories listed in the Human Health Risk 

Scoping Document for fosamine ammonium. 

Agency Response:

DuPont is correct. Revised acute toxicity category designations for the exposure routes 

identified by DuPont will be included in the registration review assessment conducted for 

fosamine ammonium. 

DuPont Comment: 

DuPont disagrees with the Agency conclusion about the possible neurotoxic effects of fosamine 

ammonium. Specifically, DuPont claims that the laboratory testing effects cited by EPA as 

neurotoxic effects are more consistent with stress from compound related systemic toxicity and 

not neurotoxicity. 

Agency Response:

DuPont’s comments on the significance and/or implications of effects observed in the acute 

neurotoxicity study in rats will be considered as part of the comprehensive assessment conducted 

for the registration review of fosamine ammonium. 

DuPont Comment:

DuPont requests the Agency waive the developmental toxicity study in non-rodent species cited 

as an anticipated data need in the Human Health Risk Scoping Document for fosamine 

ammonium. DuPont believes the study to be unnecessary and likely to provide little value to a 

risk assessment. DuPont argued that these data are not necessary given the product chemistry 

properties of fosamine ammonium; the unlikely routes of significant exposure; and the lack of 

toxicological effects seen in a developmental toxicity study conducted on rats. 
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Agency Response:

The Agency does not agree with DuPont’s presumption of no or low exposure via the oral and or 

dermal/inhalation routes; and, even if substantiated, would not preclude the need for a 

developmental toxicity study in a second species. The Agency also noted that the fact that no 

effects were seen at high doses in one species does not preclude the need for a developmental 

study in a second species. For these reasons, the Agency will require a developmental toxicity 

study in non-rodent species to support registration review. 

DuPont Comment: 

DuPont will consider providing a 28-day immuotoxicity study if there is a DCI for this endpoint. 

Following the approach to sex and species selection outlined in the EPA Memorandum of June 

16, 2009, Immunotoxicity Test Guideline: Response to CropLife America’s Comments, DuPont 

thinks that the female mouse should be used, as this is EPA’s default when there are no data to 

support one sex or species over the other. 

Agency Response: 

An immunotoxicity study is required under 40 CFR Part 158 as a part of the new data 

requirements for registration of a pesticide (food and non-food uses). If DuPont would like the 

Agency to review the study protocol prior to study initiation, the Agency encourages DuPont to 

submit a study protocol prior as early as possible in order to meet the 12 month study deadline 

that will required by the DCI. 

Data Requirements Table

The Agency will issue a DCI for the following studies listed in both the PWP and FWP. 

Data Requirement Guideline Number Listed In PWP Listed In FWP 

Avian Acute Oral 

Toxicity Study 

(passerine species) 

850.2100 

Fish Early Life-Stage 

(freshwater) (Rainbow 

trout, Bluegill sunfish) 

850.1400 

Aquatic Invertebrate 

Life-Cycle (freshwater) 

(Water flea) 

850.1300 

90-Day Inhalation 

Toxicity (rat) 

870.3465 

Developmental 

Toxicity (rabbit) 

870.3700b 

Immunotoxicity 870.7800 

UV/Visible Light 

Absorption 

830.7050 

The Agency’s anticipated data needs did not 

change and the Agency will issue a DCI for these 

studies.