vvEPA
United States Prevention, Pesticides EPA738-R-00-013
Environmental Protection And Toxic Substances January 2001
Agency (7508C)
Interim Reregistration
Eligibility Decision for
Fenthion
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United States
Environmental Protection
Agency
Prevention, Pesticides
and Toxic Substances
(7508C)
EPA738-F-00-011
January 2001
Fenthion Facts
EPA has assessed the risks of fenthion and reached an Interim Reregistration Eligibility Decision
(IRED) for this organophosphate (OP) pesticide. Provided that risk mitigation measures are adopted,
fenthion fits into its own "risk cup"-- its individual, aggregate risks are within acceptable levels.
Fenthion is not eligible for reregistration at this time but may be pending a decision by the Agency on
appropriate mitigation after consultation with stakeholders.
Used as an adult mosquiticide in Florida only,
fenthion residues in food and drinking water do not
pose risk concerns. With mitigation limiting
homeowners' and children's exposure via home
lawns and other turf, fenthion fits into its own "risk
cup." With other mitigation measures, fenthion's
worker and ecological risks also would be below
levels of concern for reregistration. The Agency is
seeking input from stakeholders at a January 17,
2001, meeting on what mitigation measures to
impose. EPA will then announce a final determination
on the risk mitigation it believes must be adopted in
order for products containing fenthion to remain
eligible for reregistration.
After this individual decision on fenthion,
EPA's next step under the Food Quality Protection
Act (FQPA) is to complete a cumulative risk
assessment and risk management decision
encompassing all the OP pesticides, which share a
common mechanism of toxicity. The interim decision
on fenthion cannot be considered final until this
cumulative assessment is complete. Further risk
mitigation may be warranted at that time.
EPA is reviewing the OP pesticides to determine whether they meet current health and safety
standards. Older OPs need decisions about their eligibility for reregistration under FIFRA. OPs with
residues in food, drinking water, and other non-occupational exposures also must be reassessed to
make sure they meet the new FQPA safety standard.
The OP Pilot Public Participation Process
The organophosphates are a group of
related pesticides that affect the functioning of the
nervous system. They are among EPA's highest
priority for review under the Food Quality Protection
Act.
EPA is encouraging the public to
participate in the review of the OP pesticides.
Through a six-phased pilot public participation
process, the Agency is releasing for review and
comment its preliminary and revised scientific risk
assessments for individual OPs. (Please contact
the OP Docket, telephone 703-305-5805, or see
EPA's web site, www.epa.gov/pesticides/op .)
EPA is exchanging information with
stakeholders and the public about the OPs, their
uses, and risks through Technical Briefings,
stakeholder meetings, and other fora. USDA is
coordinating input from growers and other OP
pesticide users.
Based on current information from
interested stakeholders and the public, EPA is
making interim risk management decisions for
individual OP pesticides, and will make final
decisions through a cumulative OP assessment.
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The fenthion interim decision is being made through the OP pilot public participation process,
which increases transparency and maximizes stakeholder involvement in EPA's development of risk
assessments and risk management decisions. EPA continues to work extensively with affected parties
to address the risks discussed in this interim decision document, which concludes the OP pilot process
for fenthion.
Uses
An insecticide, fenthion is used to control adult mosquitos in Florida only and dragonfly larvae
in contained ornamental fish production ponds in Arkansas, Florida, and Missouri only.
Annual domestic use is low— use data from 1990 to 1998 indicate an average of about
246,100 a.i. was used domestically per year (up to 343,100 Ibs a.i./year maximum). The
average amount used for mosquito control was about 96,500 Ibs a.i./year (up to 118.600 Ibs
a.i./year maximum).
Health Effects
Fenthion can cause cholinesterase inhibition in humans; that is, it can overstimulate the nervous
system causing nausea, dizziness, confusion, and at very high exposures (e.g., accidents or
major spills), respiratory paralysis and death.
Ecological Effects
Risks
Fenthion is very highly toxic to birds and highly toxic to estuarine/marine invertebrates and non-
target organisms. The mosquito adulticide use of fenthion has been implicated in several bird
kill incidents, including recent bird kills on Marco Island, Florida. These kills on Macro Island
are currently under investigation by the US Fish and Wildlife Service.
Dietary exposures from eating food crops exposed to fenthion are above the level of concern
for the entire U.S. population, including infants and children. However, these uses are being
voluntarily cancelled by the registrant, and the Agency will not refine the fenthion dietary
exposure analyses. Drinking water is not a significant source of exposure.
Although there are no homeowner uses for fenthion, residential exposure to adults and children
can occur because fenthion is used in mosquito control operations that involve wide area
adulticide applications to residential areas in Florida. Risks are of concern for homeowners
performing yard work and playing or performing other recreational activities (i.e., golfing) on
the treated areas. Risks are also of concern for children engaging in activities in areas not
limited to their residence (i.e., parks) treated with fenthion.
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• EPA also has risk concerns for workers who mix, load, and/or apply fenthion for both aerial
and ground mosquito adulticide applications.
There are potential risk concerns for acute dietary risks to birds, freshwater invertebrates and
estuarine/marine invertebrates at maximum aerial and/or ground applications.
Risk Mitigation
In order to support a reregistration eligibility decision for fenthion, the following risk mitigation
measures are being considered and will be discussed at the upcoming stakeholder meeting:
To mitigate risks to workers who mix, load and apply fenthion for ground and aerial
applications:
• require generic mixer/loader/applicator exposure data for all mosquito pesticide
applications;
handlers must use closed systems only. The current labels give protective clothing
statements for both closed system and non-closed systems. The Agency believes that
requiring closed systems for all types of mosquito control applications will result in less
exposure to workers;
add a prohibition of human Saggers to the label;
change the use rate on the label to allow the highest rate only for public health use (i.e.,
with confirmation of mosquito-vectored diseases).
To mitigate risks from aquaculture use:
eliminate the backpack sprayer method of application;
• require a handwand sprayer.
To mitigate risks to residential bystanders:
require chemical-specific deposition and turf transferable residue studies to refine the
risk assessment;
• require a developmental neurotoxicity study;
change the use rate on the label to allow the highest rate only for public health use (i.e.,
with confirmation of mosquito-vectored diseases).
• To mitigate ecological risks:
require avian reproduction studies for the northern bobwhite and the mallard to refine
the risk assessment;
• require three acute toxicity studies for the mysid shrimp: one using a formulation, one
using the sulfoxide degradate, and one using the suflone degradate.
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restrict the use of fenthion to mosquito control districts in Florida that have developed a
plan to identify critical/sensitive bird habitats and endangered species in their counties
and have addressed ways to avoid exposure to those areas;
change the use rate on the label to allow the highest rate only for public health use (i.e.,
with confirmation of mosquito-vectored diseases);
require buffer zones to protect aquatic organisms, especially invertebrates;
require certain label changes to improve applications and lessen risk to non-target
organisms.
Next Steps
Numerous opportunities for public comment were offered as this decision was being
developed. The fenthion IRED therefore is issued in final (see www.epa.gov/REDs/ or
www.epa.gov/pesticides/op ) without a formal public comment period. The docket remains
open, however, and any comments submitted in the future will be placed in this public docket.
The Agency is sponsoring a public stakeholder meeting to gather information and hear concerns
and comments about risks and possible risk mitigation for fenthion. This meeting will be held on
January 17, 2001, from 9:00 am to 5:00 pm at the Embassy Suites, 8978 International Drive,
Orlando, Florida 32819.
The Agency will revoke all fenthion tolerances because the registrant has agreed to cancel all
food uses. When the cumulative risk assessment for all organophosphate pesticides is
completed, EPA may need to pursue further risk management for fenthion.
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\
<1 UNITED STATES ENVIRONMENTAL PROTECTION AGENCY
f WASHINGTON, D.C. 2O46O
OFFICE OF
PREVENTION, PESTICIDES
AND TOXIC SUBSTANCES
CERTIFIED MAIL
Dear Registrant:
This is to inform you that the Environmental Protection Agency (hereafter referred to as EPA or
the Agency) has completed its review of the available data and public comments received related to the
preliminary and revised risk assessments for the organophosphate pesticide fenthion. The public
comment period on the revised risk assessment phase of the reregistration process is closed. Based on
comments received during the public comment period and additional data received from the registrant,
the Agency revised the human health and environmental effects risk assessments and made them
available to the public on October 21, 1999. Additionally, the American Mosquito Control Association
sponsored a Stakeholder Meeting in Orlando, Florida on October 13, 1999, where the Agency
presented the results of the revised human health and environmental effects risk assessments to the
general public. This Stakeholder Meeting concluded Phase 4 of the OP Public Participation Pilot
Process developed by the Tolerance Reassessment Advisory Committee, and initiated Phase 5 of that
process. During Phase 5, all interested parties were invited to participate and provide comments and
suggestions on ways the Agency might mitigate the estimated risks presented in the revised risk
assessments. This public participation and comment period commenced on October 21, 1999, and
closed on December 21, 1999.
Based on its review, EPA believes that the current use of fenthion poses unreasonable adverse
effects to human health and the environment, unless steps are taken to mitigate these risks. For
fenthion, the Agency is issuing its interim decision on reregistration eligibility, tolerance reassessment,
and risk management in two phases. First, EPA is publishing its interim decision on tolerance
reassesment for fenthion, which addresses risks from exposure to fenthion-treated livestock food items.
Second, EPA is also publishing its proposed strategy to manage the remaining risks from fenthion use
(occupational, residential, and environmental), which provides for an additional stakeholder involvement
process to begin in the near future. The Agency believes this risk management strategy will support an
interim decision on the reregistration eligibility of fenthion. EPA's risk management strategy outlines the
Agency's proposal on risk mitigation, then provides for a stakeholder involvement process that will
begin shortly — this public process will provide an opportunity for stakeholders to discuss the Agency's
proposed risk mitigation measures and determine the best methods for reducing the risks associated
with fenthion. Following this process, EPA will announce the specific risk mitigation measures that will
need to be implemented in order for fenthion to be eligible for reregistration. The enclosed "Interim
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Reregistration Eligibility Decision for Fenthion" which was approved on September 29, 2000, contains
the Agency's decision on the individual chemical fenthion. The reregistration eligibility decision will be
finalized once the cumulative assessment for all of the organophosphate pesticides is completed because
of exposure to children from the mosquito use.
A Notice of Availability for this Interim Reregistration Eligibility Decision for Fenthion is published
in the Federal Register. To obtain a copy of the interim RED document, please contact the OPP
Public Regulatory Docket (7502C), USEPA, Ariel Rios Building, 1200 Pennsylvania Avenue NW,
Washington, DC 20460, telephone (703) 305-5805. Electronic copies of the interim RED and all
supporting documents are available on the Internet. See http:www.epa.gov/REDs.
The interim RED is based on the updated technical information found in the fenthion public
docket. The docket not only includes background information and comments on the Agency's
preliminary risk assessments, it also now includes the Agency's revised risk assessments for fenthion
(revised as of October 13, 1999), and a document summarizing the Agency's Response to Comments.
The Response to Comments document addresses corrections to the preliminary risk assessments
submitted by chemical registrants, as well as responds to comments submitted by the general public and
stakeholders during the comment period on the risk assessment. The docket will also include
comments on the revised risk assessment, and any risk mitigation proposals submitted during Phase 5.
For fenthion, a proposal was submitted by Bayer Corporation Agriculture Division, the technical
registrant. Comments on mitigation or mitigation suggestions were submitted by various mosquito
control districts in Florida, Florida Department of Agriculture & Consumer Services, Florida
Department of Environmental Protection, Florida Mosquito Control Association, American Mosquito
Control Association, Health Canada-Pest Management Regulatory Agency, American Bird
Conservancy, other bird conservation organizations, and private citizens.
This document and the process used to develop it are the result of a pilot process to facilitate
greater public involvement and participation in the reregistration and/or tolerance reassessment
decisions for these pesticides. As part of the Agency's effort to involve the public in the implementation
of the Food Quality Protection Act of 1996 (FQPA), the Agency is undertaking a special effort to
maintain open public dockets on the organophosphate pesticides and to engage the public in the
reregistration and tolerance reassessment processes for these chemicals. This open process follows the
guidance developed by the Tolerance Reassessment Advisory Committee (TRAC), a large multi-
stakeholder advisory body that advised the Agency on implementing the new provisions of the FQPA.
The reregistration and tolerance reassessment reviews for the organophosphate pesticides are following
this new process.
Please note that the fenthion risk assessment and the attached interim RED concern only this
particular organophosphate. All food uses of fenthion will be cancelled and therefore, the final
tolerance assessment is included in this document. The Agency has also concluded its assessment of
the ecological and worker risks associated with the use of fenthion. Because the FQPA directs the
Agency to consider available information on the basis of cumulative risk from substances sharing a
common mechanism of toxicity, such as the toxicity expressed by the organophosphates through a
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common biochemical interaction with cholinesterase enzyme, the Agency will evaluate the cumulative
risk posed by the entire organophosphate class of chemicals after completing the risk assessments for
the individual organophosphates. The Agency is working towards completion of a methodology to
assess cumulative risk and the individual risk assessments for each organophosphate are likely to be
necessary elements of any cumulative assessment. The Agency has decided to move forward with
individual assessments and to identify mitigation measures necessary to address those human health and
environmental risks that have already been attributed to current uses of fenthion.
The Agency believes that currently registered uses of fenthion pose unreasonable adverse effects
to human health and the environment, and that mitigation measures are necessary. The Agency will
conduct a public process in the near future to identify the best ways to reduce the risks associated with
fenthion exposure. The process will include a public comment period on the risk mitigation proposed in
this interim RED, as well as a stakeholder meeting. At the conclusion of this process, the Agency will
announce a final determination on the risk mitigation it believes must be adopted in order for products
containing fenthion to remain eligible for reregistration. Also, if new information comes to the Agency's
attention, or if data requirements for registration (or the guidelines for generating such data) change
during this time, EPA may take appropriate regulatory action and/or require the submission of
additional data to support the reregistration of fenthion products.
This document contains a product-specific Data Call-In(s) (DCI) that outiine(s) further data
requirements for this chemical. For product-specific DCIs, the first set of required responses is due 90
days from the receipt of the DCI letter. The second set of required responses is due eight months from
the date of the DCI. Note that a generic DCI is not being issued at this time. Generic data
requirements for fenthion will be called in after the public stakeholder meeting has been held.
If you have questions regarding this document, please contact the Chemical Review Manager,
Tracy Truesdale at (703) 308-8073. For questions about product reregistration and/or the Product
DCI that accompanies this document, please contact Jane Mitchell at (703) 308-8061.
Lois A. Rossi, Director
Special Review and
Reregistration Division
Attachment
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Interim Reregistration Eligibility Decision
for
Fenthion
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TABLE OF CONTENTS
Executive Summary iv
I. Introduction 1
II. Chemical Overview 3
A. Regulatory History 3
B. Chemical Identification 3
C. Use Profile 4
D. Estimated Usage of Pesticide 6
III. Summary of Fenthion Risk Assessment 7
A. Human Health Risk Assessment 7
1. Dietary Risk from Food 10
a. Toxicity 10
b. FQPA Safety Factor 10
c. Population Adjusted Dose (PAD) 11
d. Exposure Assumptions 11
e. Food Risk Characterization 12
2. Dietary Risk from Drinking Water 13
a. Surface Water 13
b. Ground Water 14
c. Drinking Water Levels of Comparison (DWLOCs) 14
3. Occupational and Residential Risk 15
a. Toxicity 15
b. Occupational Exposure and Risk 17
(1) Occupational Exposure 17
(2) Occupational Risk Summary 19
c. Post-Application Residential Exposure and Risk 27
(1) Residential Exposure 27
(2) Post-Application Residential Risk 29
4. Aggregate Risk 30
a. Acute Aggregate Exposure and Risk 30
b. Aggregate Short-term and Intermediate-term Exposures and Risks
30
c. Chronic Aggregate Exposure and Risk 31
B. Environmental Risk Assessment 31
1. Environmental Fate and Transport 31
2. Risk to Birds and Mammals 32
a. Birds - Mosquito Adulticide Applications 32
b. Birds - Livestock Application 34
c. Mammals 34
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3. Risk to Aquatic Species 34
a. Freshwater and Estuarine/Marine Fish - Mosquito Adulticide
Applications 34
b. Freshwater and Estuarine/Marine Invertebrates - Mosquito
Adulticide Applications 34
IV. Summary of Benefits Assessment 35
A. Background 35
B. Disease and Vector Monitoring 35
C. Pests and Diseases Targeted by the Use of Fenthion 36
D. Usage of Fenthion 36
E. Comparative Efficacy and Resistance Management 37
F. Estimation of Economic Impacts of Switching to Alternatives 38
G. Benefits Conclusions 39
V. Interim Determination of Reregistration Eligibility, Tolerance Reassessment, and Risk
Management 39
A. Determination of Interim Reregistration Eligibility 39
B. Summary of Phase 5 Comments and Responses 41
C. Decision on Tolerance Reassessment 45
D. Regulatory Position 45
1. FQPA Assessment 45
a. "Risk Cup" Determination 45
b. Tolerance Summary 46
2. Endocrine Disrupter Effects 47
3. Labels 47
E. Regulatory Rationale 48
1. Risk Mitigation 48
a. Dietary Mitigation 48
(1) Acute and Chronic Dietary (Food) 48
(2) Drinking Water 49
b. Public Comment and Stakeholder Meeting Process 49
c. Proposed Risk Mitigation Measures 49
(1) Occupational Risk Mitigation 50
(2) Post-Application Residential Risk Mitigation 50
(3) Environmental Risk Mitigation 51
F. Other Labeling 51
1. Endangered Species Statement 52
2. Spray Drift Management 52
VI. What Registrants Need to Do 53
A. Manufacturing Use Products 53
1. Additional Generic Data Requirements 53
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2. Labeling for Manufacturing Use Products 53
B. End-Use Products 53
1. Additional Product-Specific Data Requirements 53
2. Labeling for End-Use Products 54
C. Existing Stocks 54
D. Labeling Changes Summary Table 54
VI. Related Documents and How to Access Them 54
VII. APPENDICES 55
Appendix A. Currently Registered Use Patterns for Reregistration 57
Appendix B. Table of Generic Data Requirements and Studies Used to Make the
Reregistration Decision 59
Appendix C. Technical Support Documents 65
Appendix D. Citations Considered to be Part of the Data Base Supporting the
Interim Reregistration Decision (Bibliography) 67
Appendix E. Generic Data Call-In 77
Appendix F. Product Specific Data Call-In 81
Appendix G. EPA's Batching of Fenthion Products for Meeting Acute Toxicity
Data Requirements for Reregistration 89
Appendix H. List of Registrants Sent This Data Call-In 91
Appendix I. List of Available Related Documents and Electronically Available
Forms
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FENTHION TEAM
Office of Pesticide Programs:
Health Effects Risk Assessment
William Hazel, Ph. D.
Jeffrey Dawson
Christine Olinger
Christina Swartz
Michael Metzger, Ph.D.
Environmental Fate (Drinking Water and Ecological^ Risk Assessment
William Erickson
Daniel Rieder
Henry Craven
Arnet Jones
Use and Usage Analysis
Michael Hennessey
Alan Halvorson
Registration Support
William Sproat, Ph.D.
George LaRocca
Risk Management
Beth Edwards
Tracy Truesdale
MarkWilhite
Susan Lewis
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GLOSSARY OF TERMS AND ABBREVIATIONS
AE Acid Equivalent
a.i. Active Ingredient
aPAD Acute Population Adjusted Dose
ARC Anticipated Residue Contribution
CAS Chemical Abstracts Service
CI Cation
CNS Central Nervous System
cPAD Chronic Population Adjusted Dose
CSF Confidential Statement of Formula
DEEM Dietary Exposure Evaluation Model
DFR Dislodgeable Foliar Residue
ORES Dietary Risk Evaluation System
DWEL Drinking Water Equivalent Level (DWEL) The DWEL represents a medium specific (i.e., drinking
water) lifetime exposure at which adverse, noncarcinogenic health effects are not anticipated to occur.
EEC Estimated Environmental Concentration. The estimated pesticide concentration in an environment,
such as a terrestrial ecosystem.
EP End-Use Product
EPA U.S. Environmental Protection Agency
FAO Food and Agriculture Organization
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
GLC Gas Liquid Chromatography
GM Geometric Mean
GRAS Generally Recognized as Safe as Designated by FDA
HA Health Advisory (HA). The HA values are used as informal guidance to municipalities and other
organizations when emergency spills or contamination situations occur.
HOT Highest Dose Tested
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/1, 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.
LEL Lowest Effect Level
LOC Level of Concern
LOD Limit of Detection
LOAEL Lowest Observed Adverse Effect Level
LOAEL Lowest Observed Adverse Effect Level
MATC Maximum Acceptable Toxicant Concentration
MCLG Maximum Contaminant Level Goal (MCLG) The MCLG is used by the Agency to regulate
contaminants in drinking water under the Safe Drinking Water Act.
• g/g Micrograms Per Gram
ug/L Micrograms Per Liter
mg/L Milligrams Per Liter
MOE Margin of Expo sure
MP Manufacturing-Use Product
ii
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MPI Maximum Permissible Intake
MRID Master Record Identification (number). EPA's system of recording and tracking studies submitted.
N/A Not Applicable
NOEC No Observable Effect Concentration
NPDESNational Pollutant Discharge Elimination System
NOEL No Observed Effect Level
NOAEL No Observed Adverse Effect Level
OP Organophosphate
OPP Office of Pesticide Programs
Pa pascal, the pressure exerted by a force of one newton acting on an area of one square meter.
PADI Provisional Acceptable Daily Intake
PAG Pesticide Assessment Guideline
PAM Pesticide Analytical Method
PHED Pesticide Handler's Exposure Data
PHI Preharvest Interval
ppb Parts Per Billion
PPE Personal Protective Equipment
ppm Parts Per Million
PRN Pesticide Registration Notice
Q! The Carcinogenic Potential of a Compound, Quantified by the EPA's Cancer Risk Model
RBC Red Blood Cell
RED Reregistration Eligibility Decision
REI Restricted Entry Interval
RiD Reference Dose
RS Registration Standard
RUP Restricted Use Pesticide
SLN Special Local Need (Registrations Under Section 24(c) ofFIFRA)
TC Toxic Concentration. The concentration at which a substance produces a toxic effect.
TD Toxic Dose. The dose at which a substance produces a toxic effect.
TEP Typical End-Use Product
TGAI Technical Grade Active Ingredient
TLC Thin Layer Chromatography
TMRC Theoretical Maximum Residue Contribution
torr A unit of pressure needed to support a column of mercury 1 mm high under standard conditions.
WHO World Health Organization
WP Wettable Powder
WPS Worker Protection Standard
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Executive Summary
EPA has completed its review of public comments on the revised risk assessments and is issuing
its interim decisions on reregistration eligibility, tolerance reassessment, and risk management for
fenthion. The decisions outlined in this document include the final tolerance reassessment decision for
fenthion because the registrant has agreed to cancel all food uses for the chemical, and thus, all fenthion
tolerances will be revoked. The Agency may need to pursue further risk management for fenthion,
however, once the cumulative assessment of the organophosphate pesticides is finalized.
The revised risk assessments are based on review of the required target data base supporting the
use patterns of currently registered products and new information received. The Agency invited
stakeholders to provide proposals, ideas or suggestions on appropriate mitigation measures before the
Agency issued its risk mitigation decision on fenthion. After considering the revised risks, as well as
mitigation proposed by Bayer Corporation Agriculture Division, the technical registrant of fenthion, and
comments and mitigation suggestions from other interested parties including various mosquito control
districts in Florida, Florida Department of Agriculture & Consumer Services, Florida Department of
Environmental Protection, Florida Mosquito Control Association, American Mosquito Control
Association, Health Canada-Pest Management Regulatory Agency, American Bird Conservancy, other
bird conservation organizations, and private citizens, EPA developed its risk management strategy for
uses of fenthion that pose risks of concern. This strategy is discussed fully in this document.
The Agency believes that certain uses of fenthion, as specified in this document pose
unreasonable adverse effects on human health and the environment, and will be ineligible for
reregistration, unless measures are taken to mitigate these risks. Accordingly, the Agency will conduct
a public involvement process to discuss and identify the best ways to reduce the risks associated with
the use of fenthion. This document outlines EPA's risk management strategy, which includes its own
proposal on risk mitigation, to be followed by a public comment period and stakeholder meeting in the
near future. Following the conclusion of this public process, the Agency will announce its final
determination on the risk mitigation measures it believes must be adopted to support a final
reregistration eligibility decision.
Fenthion is an organophosphate insecticide used as a mosquito adulticide in the state of Florida.
There were also registrations for three granular mosquito larvicide products; however, these were
recently voluntarily cancelled by the registrant, Amvac. Fenthion is also used to control lice, flies, and
ticks on cattle and swine. As a result of this reregistration process, these livestock products were
voluntarily cancelled (by Bayer) and will be phased out over the next two years. Special Local Need
registrations exist for the states of Florida, Arkansas, and Missouri to control dragonfly larvae in
contained ornamental fish production ponds (i.e., aquaculture). There was also an avicide product
(Rid-A-Bird Perch) which was cancelled in 1998. Use data from 1990 to 1998 indicate an average of
about 246,100 Ib a.i. was used domestically per year (up to 343,100 Ib a.i./year maximum). The
average amount used for mosquito control was about 96,500 Ib a.i./year (up to 118,600 Ibs a.i./year
maximum).
iv
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Overall Risk Summary
EPA's human health risk assessment for fenthion indicates some risk concerns. Both acute and
chronic dietary risks were of concern; however, as stated above, all livestock products have been
voluntarily cancelled, which eliminates all dietary exposure. The Agency does not have risk concerns
about the exposure of adults and children to fenthion from drinking water because of the conservative
nature of the screening-level models, and the fact that only minor exposure to surface water is possible
due to the application rate and method of the chemical. Applications of fenthion are typically ULV
(ultra low volume) and very little of the chemical is deposited on the ground. Because fenthion is
applied as a wide area mosquito adulticide, the Agency conducted a residential post-application risk
assessment. This assessment indicates a slight risk to toddlers for intermediate-term exposures at the
maximum use rate. The Agency also has concern for workers who mix, load, and apply fenthion for
mosquito control and for aquaculture. Ecologically, the Agency has concerns for risk to birds and
aquatic invertebrates from the use of fenthion.
To mitigate risks of concern posed by the uses of fenthion, EPA considered the mitigation
proposal submitted by the technical registrant, as well as comments and mitigation ideas from other
interested parties. Given the high toxicity of fenthion and potential risks posed to workers, residential
bystanders, birds and aquatic invertebrates, a number of mitigation measures are proposed by the
Agency. However, since fenthion has significant public health benefits and there are few alternatives
available, the Agency believes it is important that a broad stakeholder process be conducted to discuss
the risk mitigation measures outlined in this interim RED and/or develop other workable mitigation
measures that adequately protect those at risk. The proposals outlined in this document are the
Agency's ideas on the best ways to reduce the risks of concern identified. These measures will be
discussed as a part of the public comment and stakeholder meeting mentioned above.
Dietary Risk
Acute and chronic dietary risk assessments for food and drinking water exceed the Agency's
level of concern for the general U.S. population and all population subgroups, including infants and
children. For acute risk, the most highly exposed subgroup is children 1-6 years at 800% aPAD (at the
99.9th percentile). For chronic risk, the most highly exposed subgroup is children 1-6 years at 270%
cPAD. On July 13, 2000, the technical registrant (Bayer) requested a phased voluntary cancellation of
all five of their livestock products. Two products will be cancelled immediately, both with a 1-year
existing stocks provision. The other three products will be cancelled effective December 31, 2000,
each with a 1 year existing stocks provision. Therefore, this is essentially a 2-year phase out of all
fenthion livestock products. The Agency feels that allowing a 2-year phase out is justified because of
the conservative nature of the risk assessment.
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Residential Post-Application Risk
Although there are no homeowner uses, residential exposure assessments were conducted to
permit risk calculations reflecting the use of fenthion as a residential wide area mosquito adulticide.
There are no risk concerns for exposure of adults associated with any treatment scenario. For
toddlers, the combined intermediate-term risk from dermal, hand-to-mouth, object-to-mouth, and
ingestion exposures resulting from aerial mosquito control applications results in an MOE of 257 (where
the level of concern is 300). Even though this number slightly exceeds the Agency's level of concern,
the Agency does not have serious concerns for this scenario for the following reasons. The Agency
believes that the inputs and approaches used to calculate the exposures for each scenario result in worst
case estimates of exposure. The Agency also believes that adding together individual exposure values
that are thought to be conservative results in a very conservative estimate of aggregate exposure. In
addition, information from mosquito control districts in Florida indicates that the maximum use rate is
only used under situations of heavy pest infestation and a lower (typical) rate is generally used.
Restricted Entry Intervals (REIs) are not appropriate for a residential exposure situation. Deposition
studies and chemical-specific turf transferrable residue studies will be required in a generic mosquito
pesticide DCI. In addition, the Agency proposes to lower the use rate, except for situations of public
health emergency.
Occupational Risk
Occupational exposure to fenthion is of concern to the Agency. For the mosquito control use of
fenthion, several mixer/loader/applicator risk scenarios currently exceed the Agency's level of concern
(i.e., MOEs are less than 100 for short-term exposures and less than 300 for intermediate-term
exposures). The Agency does not have worker exposure data which is specific to mosquito
applications. Because this type of application varies greatly from agriculture type situations, the Agency
is requiring generic mixer/loader/applicator exposure data to be submitted for all mosquito pesticide
applications. To further mitigate risk to handlers for mosquito adulticide applications of fenthion the
Agency proposes that handlers use closed systems at all times. The Agency proposes to lower the
application rate, except for situations of public health emergency. In addition, the use of fenthion in
aquaculture exceeds the Agency's level of concern. To mitigate risk to handlers for aquaculture
applications, the Agency proposes that the backpack sprayer method of application be eliminated.
Ecological Risk
Ecological risks are also of concern to the Agency. Fenthion is very highly toxic to birds and
highly toxic to estuarine/marine invertebrates. Based on previous bird kill incidents and a recent report
of bird kills from Florida, the Agency proposes the following actions to protect birds from fenthion:
restrict the use of fenthion to certain mosquito control districts in Florida that have developed a plan to
identify critical/sensitive bird habitats and endangered species in their counties and address ways to
avoid exposure to these areas; only allow the highest use rate for public health use; require certain label
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changes to improve applications and lessen risk to non-target organisms; and require buffer zones to
protect aquatic organisms, especially invertebrates.
Also, the Agency is requiring the following ecological effects studies to be submitted for fenthion:
avian reproduction studies with the northern bobwhite and the mallard, and 3 acute toxicity studies with
the mysid shrimp: 1 testing a formulation, 1 testing the sulfoxide degradate, and 1 testing the sulfone
degradate.
Summary of Benefits of Fenthion Use - Public Health
Fenthion is considered to be a public health pesticide. The Food Quality Protection Act
(FQPA) defines a public health pesticide as a minor use pesticide used predominantly in public health
programs for vector control or other health protection uses. FQPA requires EPA to weigh the risks of
a public health pesticide against the health risk of the disease to be controlled. FQPA also amends the
definition of unreasonable adverse effects on the environment by specifying that the risks and benefits of
public health pesticides be considered separate from the risks and benefits of other pesticides. EPA is
also required to consult with the Department of Health and Human Services (DHHS) before
suspending or cancelling a public health pesticide for failure to provide data or meet conditions of
registration, if requested by a registrant of any other interested party.
The threat of spread of mosquito-vectored diseases is particularly great in Florida because the
mild climate supports year-round mosquito populations. Targeted species include nuisance salt marsh
mosquitoes and the vectors of St Louis Encephalitis, Venezuelan Equine Encephalitis, Eastern Equine
Encephalitis, Malaria, Yellow fever, West Nile Virus, and Dengue. Monitoring programs for the above
vectors and diseases are in place. Fenthion is particularly effective against salt marsh mosquitoes which
are nuisance and Venezuelan Equine Encephalitis vectoring pests over most parts of the state, and the
vector for St. Louis Encephalitis which is also widespread. The last widespread epidemic of St. Louis
Encephalitis in Florida occurred in 1990, with 223 human cases and 11 deaths.
The Agency is issuing this interim Reregistration Eligibility Document (IRED) for fenthion, as
announced in a Notice of Availability published in the Federal Register. To further discuss risk
mitigation for fenthion, a stakeholder meeting process will be held in the near future. Tolerance
reassessment for fenthion is included in this document because all food uses have been cancelled;
however, the reregistration eligibility decision for fenthion cannot be considered final until the cumulative
risk assessment for all organophosphate pesticides is complete because of exposure to children from
the mosquito use. The cumulative assessment may result in further risk mitigation measures for fenthion.
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I. Introduction
The Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA) was amended in 1988 to
accelerate the reregistration of products with active ingredients registered prior to November 1, 1984.
The amended act calls for the development and submission of data to support the reregistration of an
active ingredient, as well as a review of all submitted data by the U.S. Environmental Protection Agency
(referred to as EPA or "the Agency"). Reregistration involves a thorough review of the scientific
database underlying a pesticide's registration. The purpose of the Agency's review is to reassess the
potential hazards arising from the currently registered uses of the pesticide; to determine the need for
additional data on health and environmental effects; and to determine whether the pesticide meets the
"no unreasonable adverse effects" criteria of FIFRA.
On August 3, 1996, the Food Quality Protection Act of 1996 (FQPA) was signed into law. This
Act amends FIFRA to require tolerance reassessment of all existing tolerances. The Agency had
decided that, for those chemicals that have tolerances and are undergoing reregistration, the tolerance
reassessment will be initiated through this reregistration process. It also requires that by 2006, EPA
must review all tolerances in effect on the day before the date of the enactment of the FQPA, which
was August 3, 1996. FQPA also amends the FFDCA to require a safety finding in tolerance
reassessment based on factors including an assessment of cumulative effects of chemicals with a
common mechanism of toxicity. Fenthion belongs to a group of pesticides called organophosphates,
which share a common mechanism of toxicity - they all affect the nervous system by inhibiting
cholinesterase. Although FQPA significantly affects the Agency's reregistration process, it does not
amend any of the existing reregistration deadlines. Therefore, the Agency is continuing its reregistration
program while it resolves the remaining issues associated with the implementation of FQPA.
This document presents the Agency's revised human health and ecological risk assessments; its
progress toward tolerance reassessment; and the interim decision on the reregistration eligibility of
fenthion. It is intended to be only the first phase in the reregistration process for fenthion. The Agency
will eventually proceed with its assessment of the cumulative risk of the OP pesticides and issue a final
reregistration eligibility decision for fenthion.
The implementation of FQPA has required the Agency to revisit some of its existing policies
relating to the determination and regulation of dietary risk, and has also raised a number of new issues
for which policies need to be created. These issues were refined and developed through collaboration
between the Agency and the Tolerance Reassessment Advisory Committee (TRAC), which was
composed of representatives from industry, environmental groups, and other interested parties. The
TRAC identified the following science policy issues it believed were key to the implementation of
FQPA and tolerance reassessment:
Applying the FQPA 10-Fold Safety Factor
• Whether and How to Use "Monte Carlo" Analyses in Dietary Exposure Assessments
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• How to Interpret "No Detectable Residues" in Dietary Exposure Assessments
• Refining Dietary (Food) Exposure Estimates
• Refining Dietary (Drinking Water) Exposure Estimates
• Assessing Residential Exposure
• Aggregating Exposure from all Non-Occupational Sources
• How to Conduct a Cumulative Risk Assessment for Organophosphate or Other Pesticides with
a Common Mechanism of Toxicity
• Selection of Appropriate Toxicity Endpoints for Risk Assessments of Organophosphates
• Whether and How to Use Data Derived from Human Studies
The process developed by the TRAC calls for EPA to provide one or more documents for
public comment on each of the policy issues described above. Each of these issues is evolving and in a
different stage of refinement. Some issue papers have already been published for comment in the
Federal Register and others will be published shortly.
In addition to the policy issues that resulted from the TRAC process, the Agency issued on
September 29, 2000, a Pesticide Registration Notice (PR 2000-9) that presents EPA's approach for
managing risks from organophosphate pesticides to occupational users. The Worker PR Notice
describes the Agency's baseline approach to managing risks to handlers and workers who may be
exposed to organophosphate pesticides, and the Agency expects that other types of chemicals will be
handled similarly. Generally, basic protective measures such as closed mixing and loading systems,
enclosed cab equipment, or protective clothing, as well as increased reentry intervals will be necessary
for most uses where current risk assessments indicate a risk and such protective measures are feasible.
The policy also states that the Agency will assess each pesticide individually, and based upon the risk
assessment, determine the need for specific measures tailored to the potential risks of the chemical.
The measures included in this interim RED are consistent with the Pesticide Registration Notice.
This document consists of seven sections. Section I contains the regulatory framework for
reregistration/tolerance reassessment as well as descriptions of the process developed by TRAC for
public comment on science policy issues for the organophosphate pesticides and the worker risk
management PR notice. Section n provides a profile of the use and usage of the chemical. Section m
gives an overview of the revised human health and environmental effects risk assessments resulting from
public comments and other information. Section IV presents a summary of benefits of fenthion.
Section V presents the Agency's interim decision on reregistration eligibility and risk management
decisions. Section VI summarizes the label changes necessary to implement the risk mitigation
measures outlined in Section V. Section "VTI provides information on how to access related documents.
Finally, the Appendices lists Data Call-in (DCI) information. The revised risk assessments and related
addenda are not included in this document, but are available on the Agency's web page
www.epa.gov/pesticides/op/fenthion, and in the Public Docket.
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II. Chemical Overview
A. Regulatory History
Fenthion was first registered in the United States in 1965 as a contact and systemic
organophosphate insecticide/acaricide for mosquito and insect control on swamps, standing water,
recreation areas, alfalfa, pasture grass, forests, barns, poultry houses, nonfood areas of commercial
buildings, restaurants, and homes; for lice control on cattle (beef and non-lactating dairy) and hogs; for
control of ants, mites, leafhoppers, and aphids on ornamentals and flowers; for bird control; and for use
on rice to control mosquitoes (in the State of California only). A Registration Standard was issued in
June 1988. In the Registration Standard, the Agency classified all fenthion end-use products as
Restricted Use pesticides based on avian, fish and aquatic invertebrate toxicity. The avicide product
(Rid-A-Bird) was cancelled in March 1999. All other uses except the mosquito adulticide use in
Florida and direct livestock treatment were voluntarily cancelled by the registrant in response to the
Registration Standard.
B. Chemical Identification
FENTHION:
Common Name:
Fenthion
Chemical Name: 0,0-dimethyl O-(4-(methylthio)-w-tolyl)phosphorothioate
Chemical Family:
Organophosphate
CAS Registry Number: 55-38-9
OPP Chemical Code: 053301
Empirical Formula: C10H15O3PS2
• Molecular Weight: 278.3g/mole
• Trade and Other Names: Baytex
Basic Manufacturer: Bayer Corporation Agriculture Division
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Pure fenthion is a yellow-tan liquid with a slight garlic odor. The melting point is <-25° and the
boiling point is 105°C at 0.01 mm Hg. Fenthion is practically insoluble in water, and is soluble in
methanol, ethanol, ether, acetone, and many other organic solvents (especially chlorinated
hydrocarbons). Fenthion is stable up to 210°C, and resistant to alkali up to pH 9.0.
C. Use Profile
The following information is based on the currently registered uses of fenthion, including those
that have been voluntarily cancelled as a result of the recent risk assessments. Risk assessments for the
recent cancelled uses will be presented in this document.
Type of Pesticide: Insecticide.
Summary of Use Sites:
Food: Livestock lice/fly/tick control: As a result of the recent risk assessment, this use
has been voluntarily cancelled. Fenthion was registered to control lice, horn and face flies,
and Gulf Coast ticks on cattle and swine.
Public Health: Fenthion is registered for use as a mosquito adulticide in Florida only.
Fenthion is only registered for use in Florida due to a marketing decision made several
years ago by the registrant, Bayer. Three granular mosquito larvicide products were
recently voluntarily cancelled; these products were rarely used in the U.S.
Residential: Although there are no homeowner uses, residential post-application exposure
is expected from use of fenthion as a residential wide area mosquito adulticide.
Other Non-food: State Local Need registrations exist in Florida, Arkansas, and Missouri
to control dragonfly larvae in baitfish culture and ornamental tropical fish aquaculture.
Target Pests: adult mosquitoes (specifically Culex nigripalpus andAedes sp.),
mosquito larvae, cattle lice, horn and face flies, Gulf Coast ticks, and dragonfly larvae.
Formulation Types Registered One technical product and one soluble concentrate are
currently registered for adult mosquito control in Florida. The remaining products, a
technical for livestock products, 3 granulars, 2 ready-to-use products, 1 soluble
concentrate, and 1 impregnated ear tag have been voluntarily cancelled.
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Method and Rates of Application:
Mosquito Control Applications:
Equipment: Aerial or ground-based Ultra-Low Volume (ULV) mosquito adulticide
applications account for a vast majority of the mosquito control applications. Aerial
thermal foggers are also used for adulticide applications. Aerial and ground-based
applications of granulars as a larvicide have been voluntarily cancelled.
Rates: Aerial ULV application rates range from 0.05 to 0.10 Ib ai/acre. The
ground-based ULV maximum application rate is 0.03 Ib ai/A. The aerial thermal
fogging application rate is also 0.03 Ib ai/acre. Aerial ULV applications require that
between 0.66 and 1.3 oz formulation/A be applied while ground ULV application
volumes rage from 1.2 oz/minute to 3.6 oz/minute depending on the selected
sprayer groundspeed. Aerial thermal fogging applications require that 0.4 oz
formulation/A be applied in conjunction with up to 0.8 quarts of fuel oil.
Both aerial and ground applications of granular materials for mosquito control were
at a rate of 0.1 Ib ai/A. Granular applications required that from 5 to 10 pounds of
formulated product be applied aerially or by ground for mosquito control depending
upon the product selected. As stated above, the granular products have been
cancelled.
Direct Animal Treatments: As stated previously, these uses have been
voluntarily cancelled and will be phased out over a 2 year period.
Applications: Applications for pest control on food animals are made by pouring or
otherwise directly ladelling solutions onto the backs of the target animals (i.e.,
ready-to-use or prepared aqueous application solutions). Impregnated ear tags are
also used.
Rates: Application rates for the ready-to-use formulations on livestock range up to
0.089 oz (0.0014 Ib ai)/100 Ib on cattle. Using the average cattle weight of 600
pounds per animal, the maximum application rate for the ready-to-use formulation is
0.0084 Ib ai/animal (calculated using 2 Ib ai/gallon in formulation). The pour-on
specifies a dilution of 0.5 gallons formulation for every 4.5 gallons dilute solution
prepared where each such dilution can treat up to 258 animals depending upon size.
The maximum application rate for the ladel-on formulation, which equates to the use
of 1 oz of dilute solution per 100 cattle pounds, is (0.00067 Ib ai)/100 Ib. Again,
using an average cattle weight of 600 pounds per animal, the application rate for the
ladel-on formulation is 0.004 Ib ai/animal (calculated using 0.77 Ib ai/gallon in
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formulation). Each impregnated ear tag weighs 15 grams and contains 20 percent
fenthion. Each animal is treated using two ear tags. As such, the application rate is
6 grams ai or 0.013 Ib ai per animal.
Aquaculture Treatments:
Applications: Applications in aquaculture are intended for the control of larval
dragonflies in commercially operated freshwater ponds. The use is only for
ornamental fish or baitfish. Applications are made prior to stocking ornamental fish
such as koi carp, goldfish, comets, shubunkins, fantails, and baitfish such as shiners
and minnows. The only labels for this use are Section 24C (Special Local Need
(SLN)). The concentration of fenthion in each labelled product is 95 percent active
ingredient. The material is diluted and applied by handheld equipment to obtain an
even distribution in the treated ponds. For risk assessment purposes, the Agency
has completed calculations using low pressure handwand and backpack sprayers as
the method of application.
Rate: The application rate is based on achieving a water concentration of 0.1 ppm.
If a 5 acre pond that is 3 feet deep is treated, a total of 52.5 ounces of formulation
in sufficient water to enable uniform application to the pond is needed to complete
the application (i.e., 4 pounds of active ingredient). Single applications are allowed
2 to 4 days prior to stocking.
Use Classification: Fenthion is a restricted-use organophosphate insecticide.
D. Estimated Usage of Pesticide
This section summarizes the best estimates available for the pesticide uses of fenthion, based on
available pesticide usage information for 1990 through 1998. A full listing of all uses of fenthion, with
the corresponding use and usage data for each site, has been completed and is in the "Quantitative
Usage Analysis" document, which is available in the public docket. Approximately 246,100 Ib. a.i. of
fenthion are used annually with a maximum annual use of 343,100 Ib. a.i.
Annual Poundage: Average Maximum
Total: 246,100 Ib. a.i. 343,100 Ib. a.i.
Mosquito control: 96,500 Ib. a.i. 118,600 Ib. a.i.
Livestock: 148,000 Ib. a.i. 222,100 Ib. a.i.
Pour-on: 136,600 Ib. a.i. 204,900 Ib. a.i.
Ear tag: 11,400 Ib. a.i. 17,200 Ib. a.i.
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Fenthion is used for adult mosquito control in the state of Florida only. Ten out of 52 mosquito
control districts in Florida used fenthion in 1998. Only seven districts used fenthion in 1999. Maximum
annual percent livestock treated numbers are: 12% beef cattle (9.5% pour-on and 2.5% ear tags), 4%
dairy cattle (ear tag only), and 9% swine (pour-on).
The sources of usage data for fenthion are: 1) American Mosquito Control Association (AMCA)
1998 Survey; 2) Florida Coordinating Council on Mosquito control ("Florida Mosquito Control", 1998
white paper); 3) Registrants; 4) various Florida Mosquito Control Districts; 5) Certified/Commercial
Pesticide Application Survey 1993; and 6) EPA internal & proprietary data.
III. Summary of Fenthion Risk Assessment
Following is a summary of EPA's revised human health and ecological risk findings and
conclusions for the organophosphate pesticide fenthion, as fully presented in the documents, "Human
Health Risk Assessment: Fenthion" dated October 13, 1999, and "Transmittal of EFED RED for the
list A Chemical Fenthion,"dated May 1, 1996 (and addenda thereto). The purpose of this summary is
to assist the reader by identifying the key features and findings of these risk assessments, and to better
understand the conclusions reached in the assessments.
These risk assessments for fenthion were presented at an October 13, 1999 Stakeholder
Meeting in Orlando, Florida, which was followed by an opportunity for public comment on risk
management for this pesticide. The risk assessments presented here form the basis of the Agency's
interim risk management decision for fenthion only; the Agency must complete a cumulative assessment
of the risks of all the organophosphate pesticides before other final decisions can be made.
A. Human Health Risk Assessment
EPA issued its preliminary risk assessments for fenthion in August, 1998 (Phase 3 of the TRAC
process). In response to comments and studies submitted during Phase 3, the risk assessments were
updated and refined. The only revision that was made based on public comment was the correction of
the typical use rate. All other revisions were made as a result of further internal review or policy
changes. Major revisions to the human health risk assessment are listed below:
S Human Study Issue: The body of fenthion toxicology data includes a 28-day human
study. It is current Agency policy to make no final regulatory decision based on a human
study until a new policy has been developed to ensure that such studies meet the highest
scientific and ethical standards. This new policy is not yet in place, so the Agency has
selected doses and endpoints to calculate dietary and non-dietary risk based solely on
animal studies. In the preliminary fenthion human health risk assessment, released before
the current Agency policy was articulated, this study provided the endpoint from which the
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Reference Doses (RfDs) and Population Adjusted Doses (PADs) were calculated. In the
refined fenthion risk assessment presented here, this study and its role in the assessment
have been reconsidered.
S Dermal Absorption Factor: The dermal absorption factor was changed from 20% to
3%. The following discussion provides a rationale for the use of a 3% dermal absorption
factor for risk assessment purposes.
The fenthion database does not contain a dermal absorption study and therefore a dermal
absorption factor had to be calculated. Based on the toxicity data available for fenthion,
the use of the default 100% dermal absorption factor is not appropriate because it
substantially overestimates the toxicity of this compound via the dermal route. In a special
study conducted in the rat, a comparison of the extent of cholinesterase inhibition after a
single dose of fenthion via either the dermal or the oral route was evaluated. Here, an
absorption factor of 20% was calculated by using an oral LOAEL of 5 mg/kg (NOAEL =
1 mg/kg) and a dermal LOAEL of 25 mg/kg (NOAEL = 5 mg/kg). However, this
estimate is not adequate for use in short or intermediate term risk assessment due to the
duration of the treatment (single dose) in this study, in contrast to the multiple day
exposure scenarios assessed in the risk assessment.
The dermal risk assessments are based on oral NOAELs established in a study conducted
in monkeys. Since oral NOAELs were selected, the 20% dermal absorption factor would
be used for route-to-route extrapolation. Use of this dermal absorption factor yields
dermal equivalent doses which are unrealistically low and are not consistent with the
toxicity profile seen for fenthion or other related OPs.
During the September 16, 1999 HLARC meeting, a 3% dermal absorption factor was
calculated based on the comparison of the oral developmental LOAEL in a rabbit study
and the LOAEL in a 21-day dermal toxicity study in rabbits using the technical grade
compound based on the common endpoint of cholinesterase inhibition. Though it is
recognized that the use of a 21-day dermal toxicity study in rabbit is not optimal for
deriving a dermal absorption factor, given the currently available data it was found to yield
a more realistic estimate of dermal absorption.
More information on the dermal absorption factor can be found in the document entitled
"Fenthion- Extrapolation of dermal absorption factor for use in risk assessment" dated July
26, 2000.
S Unit Exposure Values: EPA has corrected inconsistencies in unit exposure values and
exposure scenarios noted in the previous risk assessment for handlers. The 1998 risk
assessment considered handler exposures using three different levels of personal
protection including: baseline (applicators wearing long-pants and long-sleeved shirt); using
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maximum PPE (applicators at baseline with coveralls, gloves, and a respirator); and with
the use of engineering controls (e.g., closed cabs, etc.). In this assessment, additional
levels of personal protection were considered ranging from a baseline level of protection
through the use of engineering controls in every aspect of the application process.
Fenthion labels typically require the use of long-pants, long-sleeved shirts, double layer
clothing, gloves, and respiratory protection (dust/mist masks with a protection factor of 5).
In some cases, however, lower levels of personal protection are allowed such as when a
closed loading system is used or for pilots/applicators in enclosed cabs and cockpits.
S PHED Data: PHED data for mixer/loaders of liquids were extrapolated to estimate
ready-to-use pour on applications to animals. Also, airblast application data were used to
extrapolate to an applicator during ground ULV mosquito control applications.
S The AgDRIFT Model: The AgDRIFT model was used to predict deposition after aerial
mosquito control applications. AgDRIFT is a product of the SDTF (Spray Drift Task
Force) which is a FIFRA task force comprised of pesticide manufacturers, formed to
address the spray drift issue genetically.
S Residential SOPs: Several changes were made as a result of the September 21, 1999
FIFRA SAP meeting on Residential SOPs. The following changes were made to the
fenthion assessment:
The value for estimating initial turf transferable residues was lowered from
20% to 5%;
• The turf transfer coefficient was changed from 43,000 cm2/hr (8,700 cm2/hr
for kids) to 14,500 cm2/hr (5,200 cm2/hr for kids) per hour when addressing
short-term endpoints and 7,300 cm2/hr (2,600 cm2/hr for kids) per hour for
intermediate-term endpoints;
• The number of times for toddler hand-to-mouth exposure was changed from
1.56 events per hour coupled with 350 cm2 (per event) to 20 events per hour
x 20 cm2 (per event) where 1 hand-to-mouth event (20 cm2 ) represents the
palmar surface area of 3 fingers;
• The amount of extraction from the hand by saliva was lowered from a
quantitative transfer level of 100% to 50% extraction by saliva per mouthing
event.
- Revised Percent Livestock Treated Figures: Maximum annual percent livestock
treated numbers were incorporated: 12% beef cattle (9.5% pour-on/spot and 2.5% ear
tags), 4% dairy cattle (ear tag only), and 9% swine (pour-on/spot).
- DEEM™ : The Dietary Exposure Evaluation Model was used to generate acute and
chronic dietary risk figures. This is a means of assessing dietary exposure which
incorporates consumption data generated in USDA's Continuing Surveys of Food Intakes
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by Individuals (CSFII), 1989-1992. For chronic dietary risk assessments, the three-day
average of consumption for each subpopulation is combined with residues in commodities
to determine average exposure in mg/kg/day. For refined acute dietary risk assessments,
the entire distribution of consumption events for individuals is multiplied by a distribution of
residues (probabilistic analysis, referred to as "Monte Carlo" or probabilistic assessment;
risk at 99.9th percentile of exposure reported) to obtain a distribution of exposures in
mg/kg/day.
Revised Application Rates: Typical residential risks from mosquito control use were
calculated using the corrected average aerial application rate of 0.056 Ib a.i./acre. No
correction was necessary at the maximum label rate.
1. Dietary Risk from Food. In this section, the Agency has chosen to describe the
dietary risk from food even though all food uses of fenthion have been recently voluntarily cancelled.
The dietary risk from food is high; however, this is considered to be an overestimate based on the
limited data available. Had the food uses not been voluntarily cancelled, residue data would be needed
to further refine the risk.
a. Toxicity
The Agency has reviewed all toxicity studies submitted and has determined that the toxicity
database is complete, and that it supports an interim reregistration eligibility determination for all
currently registered uses. Further details on the toxicity of fenthion can be found in the October 13,
1999 Human Health Risk Assessment. A brief overview of the studies used for the dietary risk
assessment is outlined in Table 1 in this document.
b. FQPA Safety Factor
The FQPA Safety Factor was reduced to IX. The toxicity database includes an acceptable
two-generation reproduction study in rats and acceptable prenatal developmental toxicity studies in rats
and rabbits. These studies show no increased sensitivity to fetuses as compared to maternal animals
following acute in utero exposure in the developmental rat and rabbit studies and no increased
sensitivity to pups as compared to adults in a multi-generation reproduction study in rats. There was no
evidence of abnormalities in the development of the fetal nervous system in the pre/post natal studies.
Adequate actual data, surrogate data, and/or modeling outputs are available to satisfactorily assess
dietary and residential exposure and to provide a screening level drinking water exposure assessment.
The assumptions and models used in the assessments do not underestimate the potential risk for infants
and children. Therefore, the additional 10X factor as required by FQPA was reduced to 1.
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c. Population Adjusted Dose (PAD)
The PAD is a term that characterizes the dietary risk of a chemical and reflects the Reference
Dose, either acute or chronic, that has been adjusted to account for the FQPA safety factor (i.e.,
RfD/FQPA safety factor). In the case of fenthion, the FQPA safety factor is 1; therefore, the acute or
chronic RfD equals the acute or chronic PAD. A risk estimate that is less than 100% of the acute or
chronic PAD does not exceed the Agency's risk concern.
Table 1. Summary of Toxicological Endpoints and Other Factors Used in the Human Dietary
Risk Assessment of Fenthion
Assessment
Acute Dietary
Chronic Dietary
Dose
NOAEL = 0.07 mg/kg/day
NOAEL/LOAEL = 0.02
mg/kg/day
(threshold dose)
Endpoint
Lack of plasma
ChE inhibition
at week 1
Plasma ChE
inhibition
Study
Chronic-monkey
(MRIDNo.
00147245 )
Chronic-monkey
(MRIDNo.
00147245)
UF
100a
300b
FQPA
Safety Factor
IX
IX
PAD
0.0007
mg/kg/day
0.00007
mg/kg/day
lOx for interspecies, lOx for intraspecies.
b lOx for interspecies, lOx for intraspecies, 3x for lack of a true NOAEL.
Fenthion is one of the more potent cholinesterase inhibitors, having an acute No Observed
Adverse Effect Level (NOAEL) of 0.07 mg/kg/day in a 2-year oral monkey study. This study is useful
for both acute dietary and short-term dermal/inhalation risk assessment because there was a lack of
plasma and red blood cell cholinesterase (ChE) inhibition at the NOAEL during the first week of the
study. The monkey is considered to be the most sensitive species. A lack of cholinesterase inhibition
at week 1 indicates that there would be no cholinesterase inhibition during the entire first week of
dosing. The short-term/acute Lowest Observed Adverse Effect Level (LOAEL) from the monkey
study was 0.2 mg/kg/day based on observed plasma and red blood cell ChE inhibition.
d. Exposure Assumptions
Fenthion uses that can result in dietary exposure are limited to ear tag use, pour-on applications,
and the veterinary feed-through uses for cattle and swine. Anticipated upper bound residue levels in
livestock commodities were calculated using the limited available data. Upper bound estimates of
fenthion residues in milk, beef, and pork commodities were described in detail in the C. Olinger memo
dated 9/30/97. No new data have been submitted.
Anticipated residues (ARs) for beef and milk were extrapolated from existing livestock dermal
treatment studies since no data were available at the maximum use rate and 21 day pre-slaughter
interval (PSI). These ARs are higher than current tolerance levels for cattle tissues. While these ARs
represent a best estimate using the limited data available, they are an overestimate. ARs are at the
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tolerance level for pork based on an appropriate dermal treatment study, and below tolerance level for
milk. The ARs for milk are considered reasonable since ear tags are the only dairy cattle use and
residues are not expected to be detectable as a result of that use. Residue data are needed for cattle
reflecting the maximum application rate and minimum (21 days). All types of treatments (including ear
tag treatment) would need to be represented by adequate residue data. The Agency believes that
residues in cattle tissue and milk from the ear tag use would be small compared to residues resulting
from the dermal application.
Fenthion residues in milk were monitored by USDA/PDP in 1996 and 1997; a total of 1,297
samples were analyzed with no detections. The limit of detection (LOD) for fenthion was 0.001 ppm
for all USDA/PDP laboratories. The milk monitoring data and the 21-day PSI residue estimates were
used in the acute and chronic analyses.
e. Food Risk Characterization
Generally, a dietary risk estimate that is less than 100% of the acute or chronic Population
Adjusted Dose does not exceed the Agency's risk concerns. The fenthion acute and chronic dietary
risks from food exceed the Agency's level of concern for the general U.S. population and various
population subgroups, including infants and children. The most highly exposed subgroup is children 1-6
years, with approximately 800% of the acute PAD (at the 99.9th percentile of exposure) and 270% of
the chronic PAD consumed.
In the chronic analysis, infants were the only population subgroup for which chronic dietary risk
was below the level of concern, at approximately 60% of the chronic PAD. Detailed results are shown
in Table 2. The acute critical exposure contribution and the chronic critical commodity analyses
demonstrate that estimated dietary risk is due largely to potential residues in beef meat and fat and that
milk is a minor contributor to acute and chronic dietary risk.
Available USDA monitoring data on beef liver did not include all fenthion residues of concern,
but qualitatively support the results of the dietary exposure analyses conducted using livestock direct
treatment study data.
The chronic and acute analyses do not take into consideration the potential for reduction of
fenthion residues in cooked/canned/processed livestock commodities, since there are no chemical-
specific cooking studies and for this reason likely overestimate dietary exposure. The Agency will not
refine the fenthion dietary exposure analyses further since this use is being cancelled.
12
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Table 2. Acute and Chronic Dietary Exposure/Risk Estimates for Fenthion
Population Subgroup
General US Population
All Infants (<1 yr)
STursing Infants (<1 year old)
STon-Nursing Infants (<1 yr)
Children (1-6)
Children (7-12 years)
Females (13-19 years)
Females (13-50 years)
Males (13-19 years)
Males (20+ years)
Acute Assessment
(99.9th %-ile)
Exposure
(mg/kg/day)
0.003274
0.004124
0.003312
0.004350
0.005627
0.003709
0.002893
0.002390
0.002772
0.002509
%aPAD
470
590
470
620
800
530
410
340
400
360
Chronic Assessment
Exposure
(mg/kg/day)
0.000094
0.000040
0.000036
0.000042
0.000187
0.000135
0.000087
0.000073
0.000116
0.000088
%cPAD
130
57
51
60
270
190
120
100
170
130
2. Dietary Risk from Drinking Water
Drinking water exposure to pesticides can occur through ground water and surface water
contamination. EPA considers both acute (one day) and chronic (lifetime) drinking water risks and
uses either modeling or actual monitoring data, if available, to estimate those risks. Modeling is
considered to be an unrefined assessment and provides a high-end estimate of risk. In the case of
fenthion, the only use that could potentially cause contamination of drinking water is the mosquito use
which involves aerial applications and/or ground applications in Florida. For the livestock use, fenthion
is either contained within an ear tag or is spot treated to livestock. These uses are not expected to
result in significant exposures to drinking water sources. Limited groundwater monitoring data are
available for fenthion, but the utility of these data are limited by the fact that only the parent compound
was analyzed. No surface water monitoring data were available; therefore, modeling was used to
estimate drinking water risks from the mosquito adulticide use.
The environmental fate data base for fenthion is incomplete. However, it is clear that fenthion
degrades by aerobic microbial metabolism with a half-life of <1 day in aerobic soil and 11 days under
anaerobic aquatic conditions. Although no clear degradation rates are available, fenthion also probably
degrades by photolysis in water. No mobility studies with unaged fenthion have been submitted;
however, since fenthion degrades rapidly and thermal fogs and ULV are the only terrestrial uses of
fenthion, there probably would be no serious groundwater contamination from the parent compound.
a. Surface Water
Since fenthion is either contained within an ear tag or is spot treated to livestock; these uses are
not expected to result in significant exposures to drinking water sources. However, the use of fenthion
13
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as a mosquito adulticide requires the active ingredient to remain suspended in air for a period of time,
rather than quickly depositing on the ground. This application technique facilitates drift, reduces
deposition, and widens the area of deposition. Therefore, there is potential for this use to result in
surface water exposure from spray drift.
A conservative screening level estimate of potential fenthion residues in surface water was
generated using the GENEEC model. These Estimated Environmental Concentrations (EECs) were
developed for a 1 hectare (ha) by 2 meter (m) deep pond adjacent to a 10 ha treated area. Inputs to
GENEEC included an assumption of 12 applications at 7 day intervals at a rate of 0.1 Ib ai/acre, an
assumed aerial spray drift of 5%, an assumed soil half-life of 3 days, a K^ value of 1500, and an
assumed aquatic half-life of 6 days. Over a 3-year period from 1993-1996, fenthion was applied in
Lee County, FL an average of approximately 4 times/month.
The EECs thus generated are to be used for determining potential drinking water exposure and
risk. The peak concentration for determination of acute exposure and risk is 1.33 ppb and the 56-day
average concentration for determination of chronic exposure and risk is 0.19 ppb.
As a means of estimating the relative magnitude of potential risk associated with fenthion in
drinking water compared to food and residential sources, these EECs were compared to the PADs.
Conservatively modeled fenthion exposure estimates due to drinking water alone (i.e., without
considering food sources) indicate that a small amount of the aPAD and cPAD could maximally be
utilized by residues in drinking water alone. There is little concern for adults and children from exposure
to fenthion in drinking water because: (i) the EECs utilized in these calculations were derived from
conservative, screening-level models; and (ii) only minor exposure to surface water is possible due to
the application rate (ULV) and method (low deposition).
b. Ground Water
Limited groundwater monitoring data are available for fenthion but the utility of these data are
limited by the fact that only the parent compound was analyzed; fenthion is not as persistent as the five
regulated metabolites of lexicological concern. In addition, Florida was not tested (Florida is the only
state in which fenthion is used as a mosquito adulticide). There are no terrestrial agricultural uses of
fenthion and since these uses represent the primary drinking water source of exposure, the potential for
drinking water exposure is very low. The Agency believes that the only use that could potentially cause
contamination of drinking water is the mosquito use which involves aerial applications and/or ground
applications in Florida.
c. Drinking Water Levels of Comparison (DWLOCs)
To determine the maximum allowable contribution of water-containing pesticide residues
permitted in the diet, EPA first looks at how much of the overall allowable risk is contributed by food
14
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(and if appropriate, residential uses) then determines a "drinking water level of comparison"(DWLOC)
to determine whether modeled or monitoring levels exceed this level. The Agency uses the DWLOC
as a surrogate to capture risk associated with exposure from pesticides in drinking water. The
DWLOC is the maximum concentration in drinking water which, when considered together with dietary
exposure, does not exceed a level of concern.
Because the dietary risks exceeded the Agency's level of concern, DWLOCs were not
calculated for fenthion.
3. Occupational and Residential Risk
Occupational workers can be exposed to a pesticide through mixing, loading, and/or applying a
pesticide, or re-entering treated sites. Residents or homeowners can be exposed to fenthion by
entering or performing other activities on treated areas. Occupational handlers of fenthion include:
mixers/loaders, applicators, and Saggers for mosquito control uses; applicators for livestock use; and
applicators for the aquaculture use. Although there are no homeowner uses of fenthion, residential
exposure to adults and children can occur from the use of fenthion as a wide area mosquito adulticide.
Risk for all of these potentially exposed populations is measured by a Margin of Exposure (MOE)
which determines how close the occupational or residential exposure comes to a No Observed
Adverse Effect Level (NOAEL). Generally, MOEs greater than 100 do not exceed the Agency's risk
concern. However, in the case of fenthion, 300 is the target MOE for intermediate exposure because
of a lack of a definitive NOAEL in the 2-year oral monkey study.
a. Toxicity
The toxicity of fenthion is integral to assessing the occupational and residential risk. All risk
calculations are based on the most current toxicity information available for fenthion.
A 21-day dermal toxicity study in rats is not available in the fenthion database. Generally, it is
this study that is preferred to assess the potential dermal toxicity of a chemical. For fenthion, two
acceptable dermal toxicity studies in the rabbit are available; however, these studies are not considered
to accurately represent the potential dermal toxicity of fenthion to humans. Data available in the rat
indicates that organophosphates, like fenthion, are activated in the liver. However, this process does
not occur to the same extent in the rabbit due to the high levels of arylesterases (which quickly detoxify
OPs before they reach the liver) present in the rabbit bloodstream. Therefore, the 21-day dermal
toxicity studies in the rabbit were not used for endpoint selection.
At present, the dermal risk assessments are based on oral NOAELs established in a study
conducted in monkeys. In this study, the monkeys were orally dosed with fenthion at 0.02, 0.07 and
0.20 mg/kg/day. No inhibition of plasma cholinesterase activity was seen at 0.02 or 0.07 mg/kg/day at
the week 1 measurement. Upon longer exposures, plasma ChE was frequently inhibited at 0.02
15
-------
mg/kg/day such that this level was deemed to be a threshold level. Therefore, the threshold
NOAEL/LOAEL for plasma ChE inhibition was 0.02 mg/kg/day and a NOAEL of 0.07 mg/kg/day
was chosen due to the lack of plasma ChE inhibition during the first week of the study.
Table 3a. Summary of Toxicological Endpoints and Other Factors Used in the Human
Occupational and Residential Risk Assessments for Fenthion
Assessment
Short-Term Dermal
Intermediate- Term
Dermal
Short-Term
Inhalation
Intermediate-Term
Inhalation
Dose
NOAEL=0.07
mg/kg/day
Threshold
NOAEL/LOAEL =
0.02 mg/kg/day
NOAEL=0.07
mg/kg/day
Threshold
NOAEL/LOAEL =
0.02 mg/kg/day
Endpoint
Lack of plasma ChE
inhibition at week 1
Plasma ChE inhibition
Lack of plasma ChE
inhibition at week 1
Plasma ChE inhibition
Study
2-year feeding study -monkey
(MRID 00147245)
2-year feeding study -monkey
(MRID 00147245)
2-year feeding study -monkey
(MRID 00147245)
2-year feeding study -monkey
(MRID 00147245)
Absorption
factor
3%a
3%a
100%b
100%b
3% based on a comparison of LOAELs in a rabbit developmental study (MRID 40462701) and a 21-day dermal
toxicity study in rabbits (MRID 40329501).
100% in lieu of any data to indicate otherwise.
Fenthion is classified as Toxicity Category n for acute oral, dermal, and inhalation toxicity. This
chemical was classified as Toxicity Category m for eye irritation and Category IV for dermal irritation.
Acute toxicity studies did not reveal any gender bias in the toxicity profile of fenthion. In the acute
dermal study for fenthion, the LD50 for both sexes combined was 963 mg/kg/day. In the case of the
acute inhalation study the LC50 was 0.507 mg/L and 0.454 mg/L for males and females, respectively.
Refer to Table 3b for acute toxicity of fenthion.
Table 3b. Acute Toxicity Profile for Occupational Exposure for Fenthion
Study
81-1. Acute Oral-rats
81-2. Acute Dermal -
rabbits.
81-3. Acute Inhalation -
rats.
81-4. Primary Ocular
Irritation - rabbits.
81-5. Primary Dermal
Irritation - rabbits.
81-6. Dermal
Sensitization - guinea pigs
MRID
40186704
40186705
40186706
40186708
40186709
40186710
Results
LD50 = 405 (302-681) mg/kg, males
= 586 (461-791) mg/kg females
LD50 = 963 (744-1 162) mg/kg for both sexes combined
LC50 = 0.507 (0.409 - 0.695) mg/L, males
= 0.454 (0.349- 0.658) mg/L, females
Deaths in females and tremors and ataxia (both sexes) at lowest doses
(0.209 mg/L).
No cornea or iris irritation was noted. Discharge, redness and swelling were
noted in the conjunctiva in all rabbits that were reversed after two days.
PII = 0
Not a sensitizer in the Magnusson-Kligman maximization study
Toxicity
Category
II
II
II
III
IV
NA-
16
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b. Occupational Exposure and Risk
(1) Occupational Exposure
Chemical-specific exposure data were not available for fenthion, so exposures and risks to
fenthion handlers were assessed using data from the Pesticide Handlers Exposure Database
(PHED), and standard assumptions about average body weight, work day, daily areas treated, volume
of pesticide used, etc. The data and exposure factors utilized represent the best information currently
available to the Agency for completing these kinds of assessments; the application rates are derived
directly from fenthion labels and typical use information if available. The exposure factors (e.g., body
weight, amount treated per day, protection factors, etc.) are all standard values that have been used by
the Agency over several years, and the PHED unit exposure values are the best available estimates of
exposure. Some PHED unit exposure values are high quality while others represent low quality, but all
are the best available data. The quality of the data used for each scenario assessed is discussed in the
document "The ORE aspects of the HED Chapter of the Reregistration Eligibility Decision Document
(RED) for Fenthion" dated October 1, 1999 which is available in the public docket and on the internet
Anticipated use patterns, application methods and range of application rates were derived from
current labeling. Application rates specified on fenthion labels range from 0.03 to 0.10 Ib ai/acre for
mosquito control applications (allowable maximum depends upon the method of application). Animal
and aquaculture maximum use rates were defined based on the size of the animal or of the ponds. For
these scenarios, the Agency defined a likely maximum based on estimates of what is likely to be treated
(i.e., number of cattle and pond size were defined for risk assessment purposes). Wherever available,
both maximum and average (typical) application rates are used in each assessment.
The following assumptions and factors were used in order to complete this exposure assessment:
• An average occupational work day interval is 8 hours per workday. The values used by the
Agency to represent the amount of acres that can be treated in a day (or application volumes as
appropriate) for each scenario include:
(la) mixing/loading liquids for mosquito control fixed-wing aerial applications to 7500 acres per
day (see further explanation below);
(Ib) mixing/loading liquids for mosquito control ground-fogger applications to 3000 acres per
day (see further explanation below);
(2) loading granular materials for mosquito control fixed-wing aerial applications to 80 or 800
acres per day (see further explanation below);
(3) applying liquids using aerial equipment (includes both ULV and thermal fogger) for
mosquito control applications to 7500 acres per day (see further explanation below);
(4) applying liquids using ULV ground-fogger equipment for mosquito control to 3000 acres
per day (see further explanation below);
17
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(5) applying granulars using aerial equipment for mosquito control applications to 80 or 800
acres per day (see further explanation below);
(6) applying the ready-to-use solutions to livestock (cattle and swine) to 200 animals per day;
(7) applying cattle ear tags to 200 animals per day;
(8) mixing/loading/applying liquids to livestock via ladeling to 200 animals per day;
(9) loading/applying granulars for ground-based mosquito larvicide control applications to 5
acres per day;
(10) mixing/loading/applying liquids for aquaculture using low pressure handwand sprayers to a
single 2.5 or 5 acre pond per day;
(11) mixing/loading/applying liquids for aquaculture using backpack sprayers to a single 2.5 or
5 acre pond per day;
(12) flagging during aerial application of liquids to 7500 acres per day (see further explanation
below); and
(13) flagging during aerial application of granulars to 80 or 800 acres per day (see further
explanation below).
The Agency typically uses a maximum of 1200 acres per day for assessing risks to aerial
applicators in agricultural scenarios. Mosquito control applications, however, are distinctly
different from the typical agricultural scenario. For the liquid mosquito control formulation, aerial
applications are either Ultra-Low Volume (ULV) or thermal fog. Similarly, ground-based
applications are ULV. According to The Use of Aircraft in Agriculture (Ackeson and Yates,
FAO/UN 1974), the number of acres treated using aerial ULV techniques can reach as high as
5000 acres per hour for fixed-wing aircraft and 1500 acres per hour for helicopters. The
average number of acres per day that were treated by air in Florida was defined as 6600 acres
per day using 1993 to 1995 data. Since the exposure scenarios of concern are short- or
intermediate-term, a value of 7500 acres per day per individual was selected for the aerial
application of liquids exposure scenario. Likewise, for ground-based ULV applications, the
techniques and number of acres that can be treated per day are distinctly different from typical
agricultural scenarios. Based on the liquid mosquito control label application parameters,
approximately 3000 acres per day can be treated. For granular application, the Agency
estimated that 800 acres can be treated per day.
The animal assessments were based on cattle since they are larger than swine and the unit
application rates were higher for cattle. Treated cattle were assumed to weigh 600 pounds. No
scenario-specific data are available to the Agency with which to assess the cattle pour-on uses.
As such, the Agency has used data for the open mixing of liquids to calculate the exposures for
this scenario because it appears to be the best data available with which to assess this scenario.
The Agency did not use these data for the ladel-on scenario because that process also involves
additional activities that are not thought to be represented by the mixing/loading data for liquids.
18
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Average body weight of an adult handler is 70 kg. This body weight is used in all assessments
since the endpoints of concern are not sex-specific (i.e., the cholinesterase inhibition could be
assumed to occur in males or females).
All handler calculations were completed using typical (if available) and maximum labeled
application rates for each scenario.
Occupational handler exposure assessments are conducted by the Agency using different levels
of personal protection. The Agency typically evaluates all exposures with minimal protection and then
adds additional protective measures using a tiered approach to obtain an appropriate MOE (i.e., going
from minimal to maximum levels of protection). The lowest suite of personal protective equipment
(PPE) is baseline PPE. If required (i.e., MOEs are less than 100), increasing levels of risk mitigation
(PPE) are applied. If MOEs are still less than 100, engineering controls (EC) are applied. In some
cases, EPA will conduct an assessment using PPE or ECs taken from a current label. The levels of
protection that formed the basis for calculations of exposure from fenthion activities include:
Baseline: Long-sleeved shirt and long pants, shoes and socks.
Minimum PPE: Baseline + chemical resistant gloves and a dust/mist respirator with a
protection factor of 5.
• Maximum PPE: Baseline + coveralls, chemical resistant gloves, and an air purifying respirator
with a protection factor of 10.
Engineering Engineering controls such as a closed cab airplane or closed loading system
controls: for granulars or liquids. Engineering controls are not applicable to handheld
application methods; there are no known devices that can be used to
routinely lower the exposures for these methods.
These were combined to result in 8 different combinations of PPE.
The Agency has completed two distinct risk assessments for fenthion handlers; short-term
duration (1-7 days) and intermediate-term duration (>7 days). The rationale behind this approach is
that an insufficient use and usage data set is available to establish that intermediate-term exposures do
not occur. In fact, for many situations with fenthion, the Agency was able to develop several plausible
scenarios for which intermediate-term exposures can occur (i.e., data from Lee County mosquito
control district indicate that application events occur 50 to 60 times per year). MOEs for all short- and
intermediate-term scenarios may be found in the October 13, 1999 Human Health Risk Assessment for
Fenthion. There are currently no products containing fenthion for which the Agency believes that
occupational post-application exposures would be of concern.
(2) Occupational Risk Summary
In the revised assessment, risks for handlers were assessed using the same endpoints for both
dermal and inhalation exposures. The resulting risks (MOE values) were then added in order to obtain
19
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an overall risk for each applicator that accounted for both dermal and inhalation exposures for each
exposure duration considered. Dermal and inhalation risks are mitigated using different types of
protective equipment, so it may be acceptable to add a pair of gloves and not a respirator, and vice
versa. All of the risk calculations for handlers completed in this assessment are included in Appendix A
of the document "The ORE aspects of the HED Chapter of the Reregistration Eligibility Decision
Document (RED) for Fenthion" (i.e., ORE chapter) dated October 1, 1999.
For occupational use of fenthion during wide area mosquito adulticide ULV applications, five
different exposure scenarios were assessed. Two exposure scenarios were assessed for occupational
use during aquaculture applications. There are no fenthion products labelled for homeowner use;
therefore, risks to residential handlers were not assessed. Although the granular mosquito larvicide
products and all livestock uses of fenthion were recently cancelled, the risks for these uses will be
identified in this document. In the risk tables that follow, the cancelled uses and corresponding MOEs
will be shown in italics. Four exposure scenarios were assessed for occupational use during mosquito
larvicide applications. Three exposure scenarios were assessed for occupational use during
applications to food animals in agriculture. Within each of the scenarios, further analyses were
conducted to determine the MOE at typical and maximum application rates, and at maximum and
typical acreage, where applicable. Each of these analyses is included in Appendix A, Tables 1-10 of
the ORE chapter. Tables 1 through 6 of Appendix A in the ORE chapter illustrate how the calculations
were performed to define the MOEs for handlers in this risk assessment. Tables 7 and 8 provide
summaries of the MOE values calculated for each route of exposure, dermal and inhalation,
respectively, in the risk assessment. Tables 9 and 10 provide the information that is key to interpreting
the overall results of the risk assessment because they contain the overall risks calculated using several
combinations of personal protection. The reader is referred to these tables for more information on this
comprehensive assessment.
The following tables summarize the risk concerns after all assessments were revised using the
most current data and assumptions for occupational handlers, based on combined dermal and inhalation
exposures. The tables presented in this summary document outline the risks that remain of concern at
the highest possible level of protection depending upon the feasibility (i.e., those scenarios that have
MOEs < 100 for short-term exposures and MOEs < 300 for intermediate-term exposures). Note that
the scenarios that are not of concern at the highest level of protection (i.e., MOEs > 100 or MOEs >
300) are not reported in this document, but may be found in the comprehensive worker risk tables in
Appendix A of the ORE chapter.
(a) Occupational Handler Risks
The scenario numbers listed below correspond to scenario numbers detailed and discussed in
Appendix A of the ORE chapter.
20
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i) Mosquito Control
For the mosquito control uses of fenthion, 32 combinations of differing rates, acreages, and
application methods for short-term and intermediate-term exposures were assessed; of these, 7 have
remaining risk concerns for short-term and intermediate-term exposures. All MOEs in the tables below
are based on combined dermal and inhalation risks. The mosquito control scenarios with remaining risk
concerns at the highest feasible level of protection are:
(la) mixing/loading (M/L) liquids for aerial application (at both maximum and typical
application rates). (Concern for both short-term and intermediate-term exposures);
(Ib) mixing/loading liquids for ground fogger application (at both maximum and typical
application rates). (Concern for intermediate-term exposures only).
(3) aerial application of liquid sprays (at both maximum and typical application rates).
(Concern for both short-term and intermediate-term exposures);
(4) ground fogger application (at the maximum rate only for short-term exposures, at both the
maximum and typical rate for intermediate-term exposures);
(5) aerial application of granulars (at the maximum and typical application rates). (Concern
for both short-term and intermediate term exposures);
(9) ground-based granular application (at the maximum application rate). (Concern for both
short-term and intermediate-term exposures);
(12) flagging for aerial application of liquid sprays (at both maximum and typical application
rates). (Concern for intermediate-term exposures only).
ii) Livestock Applications
For the livestock use, scenarios with risks of concern at baseline, once all refinements were
made, are reported below, along with the risk estimates with increasing levels of protection. The
scenarios that do not have risks of concern (i.e., MOEs > 100 for short-term exposures and MOEs
>300 for intermediate-term exposures) are not reported here, but can be found in the comprehensive
tables in Appendix A of the ORE chapter. The scenario numbers listed below correspond to scenario
numbers detailed and discussed in Appendix A of the ORE chapter. For these livestock uses of
fenthion, the Agency assessed 6 combinations of rates, gallons used, and application methods for short-
term and intermediate-term exposures. Each combination was assessed at baseline, and with a single
layer of clothing and gloves. A quantitative risk assessment was completed for application of cattle ear
tags and for mixing/loading/applying liquids to livestock via ladeling because appropriate exposure data
were not available. For short-term and intermediate-term exposures, the ready-to-use products have
risks of concern at the baseline level of protection. With the addition of a single layer of clothing and
gloves, the MOEs are well above the Agency's level of concern. Fenthion livestock labels do not
contain protective clothing requirements.
21
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The exposure scenarios are:
(6) applying the ready-to-use solutions to livestock;;
(7) applying cattle ear tags;
(8) mixing/loading/applying liquids to livestock via ladeling.
iii) Aquaculture Applications
As with the livestock scenarios reported above, the aquaculture exposure scenarios with risks of
concern at the highest level of protection feasible are reported below. The level of concern for short-
term exposures is 100 and for intermediate-term exposures is 300.
The exposure scenarios are:
(10) mixing/loading/applying liquids for aquaculture using low pressure handwand sprayers;
(11) mixing/loading/applying liquids for aquaculture using backpack sprayers.
22
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TABLE 4. Remaining Risk Concerns for Occupational Handlers: Combined Short-Term Dermal and Inhalation MOEs
Scenario
(la) Mixing/loading
Liquids for Aerial
Application
(3) Aerial Application
of Liquid Sprays
(4) Ground Fogger
Application
(5) Aerial Application
of Granulars
(6) Ready-to-Use
Package For Livestock
(7) Ear Tags For Cattle
(8) Ladel On For
Livestock
(9) Ground-based
Granular Application
??
Rates
??
??
??
??
??
??
??
??
??
??
??
??
??
??
Acres
??
??
??
??
??
??
??
??
??
??
??
??
??
??
Summary MOEs for Combinations of Dermal and Inhalation Protective Measures
Baseline
0.1
0.1
Not
Feasible
Not
Feasible
3.6
6.7
Not
Feasible
Not
Feasible
Not
Feasible
Not
Feasible
33.1
No Data
No Data
27.1
Single Layer,
Gloves
&NO
Respirator
3.5
6.2
Not Feasible
Not Feasible
4.7
8.7
Not Feasible
Not Feasible
Not Feasible
Not Feasible
1543.2
No Data
No Data
28.7
Single
Layer,
Gloves
&Pf5
Respirator
2.8
5.0
Not Feasible
Not Feasible
3.0
5.6
Not Feasible
Not Feasible
Not Feasible
Not Feasible
1246.4
No Data
No Data
23.9
Single Layer,
Gloves
&PflO
Respirator
8.1
14.4
Not Feasible
Not Feasible
7.1
13.3
Not Feasible
Not Feasible
Not Feasible
Not Feasible
3600.8
No Data
No Data
34.4
Double Layer,
Gloves
&NO
Respirator
3.8
6.8
Not Feasible
Not Feasible
4.9
9.2
Not Feasible
Not Feasible
Not Feasible
Not Feasible
1705.7
No Data
No Data
42.0
Double Layer,
Gloves
&Pf5
Respirator
8.7
15.6
Not Feasible
Not Feasible
7.3
13.6
Not Feasible
Not Feasible
Not Feasible
Not Feasible
3888.9
No Data
No Data
53.3
Double Layer,
Gloves
&PflO
Respirator
10.4
18.5
Not Feasible
Not Feasible
7.7
14.5
Not Feasible
Not Feasible
Not Feasible
Not Feasible
4629.6
No Data
No Data
55.2
Eng.
Controls
2.8
5.0
??
??
3.0
5.6
??
??
??
??
Not
Feasible
Not
Feasible
Not
Feasible
Not
Feasible
23
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Scenario
(10) Low Pressure
Handwand Application
of 95% Liquid
(11) Backpack
Application of 95%
Liquid
(12) Flagging For
Aerial Application of
Liquid Sprays
??
Rates
??
??
??
??
0.1
0.056
Acres
??
??
??
??
7500
7500
Summan
Baseline
0.4
0.8
No Data
No Data
9.6
17.2
Single Layer,
Gloves
&NO
Respirator
28.6
57.1
11.7
23.3
9.2
16.4
MOEs for Combinations of Dermal and Inhalation Protective Measures
Single
Layer,
Gloves
&Pf5
Respirator
22.2
44.4
9.5
19.0
15.2
27.1
Single Layer,
Gloves
&PflO
Respirator
77.0
154.1
15.7
31.4
16.5
29.5
Double Layer,
Gloves
&NO
Respirator
29.8
59.6
15.7
31.4
9.6
17.2
Double Layer,
Gloves
&Pf5
Respirator
71.6
143.3
22.7
45.4
16.3
29.2
Double Layer,
Gloves
&PflO
Respirator
86.9
173.8
24.0
48.0
17.9
32.0
Eng.
Controls
Not
Feasible
Not
Feasible
Not
Feasible
Not
Feasible
480.4
857.8
24
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Table 5. Remaining Risk Concerns for Occupational Handlers: Combined Intermediate-Term Dermal and Inhalation MOEs
Scenario
(la)
Mixing/loading
Liquids for
Aerial
Application
(Ib)
Mixing/loading
Liquids for
Ground Fogger
Application
(3) Aerial
Application of
Liquid Sprays
(4) Ground
Fogger
Application
(5) Aerial
Application of
Granulars
??
Rate
??
??
??
??
??
??
??
??
??
??
??
??
Acres
??
??
??
??
??
??
??
??
??
??
??
??
Summary MOEs for Combinations of Dermal and Inhalation Protective Measures
Baseline
0.02
0.04
0.18
0.33
Not
Feasible
Not
Feasible
1.02
1.91
Not
Feasible
Not
Feasible
Not
Feasible
Not
Feasible
Single Layer,
Gloves
&NO
Respirator
1.0
1.8
8.2
15.4
Not Feasible
Not Feasible
1.3
2.5
Not Feasible
Not Feasible
Not Feasible
Not Feasible
Single
Layer,
Gloves
&PF5
Respirator
ERR
ERR
ERR
ERR
Not Feasible
Not Feasible
ERR
ERR
Not Feasible
Not Feasible
Not Feasible
Not Feasible
Single Layer,
Gloves
&PF10
Respirator
2.3
4.1
19.2
36.0
Not Feasible
Not Feasible
2.0
3.8
Not Feasible
Not Feasible
Not Feasible
Not Feasible
Double Layer,
Gloves
&NO
Respirator
1.1
1.9
9.1
17.1
Not Feasible
Not Feasible
1.4
2.6
Not Feasible
Not Feasible
Not Feasible
Not Feasible
Double Layer,
Gloves
&PF5
Respirator
2.5
4.4
20.7
38.9
Not Feasible
Not Feasible
2.1
3.9
Not Feasible
Not Feasible
Not Feasible
Not Feasible
Double Layer,
Gloves
&PF10
Respirator
3.0
5.3
24.7
46.3
Not Feasible
Not Feasible
2.2
4.1
Not Feasible
Not Feasible
Not Feasible
Not Feasible
Eng. Controls
??
??
??
??
??
??
??
??
??
??
??
??
25
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Scenario
(6) Ready-to-Use
Package For
Livestock
(7) Ear Tags For
Cattle
(8) Ladel On For
Livestock
(9)
Ground-based
Granular
Application
(10) Low
Pressure
Handwand
Application of
95% Liquid
(11) Backpack
Application of
95% Liquid
(12) Flagging For
Aerial
Application of
Liquid Sprays
(13) Flagging For
Aerial
Application of
Granulars
??
Rate
??
??
??
??
??
??
??
??
??
??
??
??
Acres
??
??
??
??
??
??
??
??
??
??
??
??
Summary MOEs for Combinations of Dermal and Inhalation Protective Measures
Baseline
9.45
No Data
No Data
7.73
0.12
0.23
No Data
No Data
2.75
4.90
74.79
133.55
Single Layer,
Gloves
&NO
Respirator
440.9
No Data
No Data
8.2
8.2
16.3
3.3
6.7
2.6
4.7
88.4
157.8
Single
Layer,
Gloves
&PF5
Respirator
??
No Data
No Data
??
??
??
??
??
ERR
ERR
ERR
ERR
Single Layer,
Gloves
&PF10
Respirator
1028.8
No Data
No Data
9.8
22.0
44.0
4.5
9.0
4.7
8.4
277.8
496.0
Double Layer,
Gloves
&NO
Respirator
487.3
No Data
No Data
12.0
8.5
17.0
4.5
9.0
2.7
4.9
97.2
173.6
Double Layer,
Gloves
&PF5
Respirator
1111.1
No Data
No Data
15.2
20.5
40.9
6.5
13.0
4.7
8.3
291.7
520.8
Double Layer,
Gloves
&PF10
Respirator
1322.8
No Data
No Data
15.8
24.8
49.6
6.9
13.7
5.1
9.1
388.9
694.4
Eng. Controls
Not Feasible
Not Feasible
Not Feasible
Not Feasible
Not Feasible
Not Feasible
Not Feasible
Not Feasible
??
??
??
??
26
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iv) Post-Application Occupational Risk
Occupational post-application risks were not assessed because the Agency believes there are no
applicable fenthion product use patterns. Mosquito control applications are addressed in the residential
post-application risk assessment summarized below and livestock pest control applications are not
considered an occupational post-application risk assessment required by the Agency.
c. Post-Application Residential Exposure and Risk
(1) Residential Exposure
Although there are no homeowner uses of fenthion, residential exposure can occur because
fenthion is used in mosquito control operations that involve wide area adulticide applications to
residential areas. This exposure scenario has been selected because it is likely that people will spend
time outdoors following mosquito control adulticide applications and come in contact with fenthion
deposited on turf. The Agency conducted risk assessments for both adults and children who are
exposed as follows:
Mosquito control applications are the only post-application concern for residential settings and
the general population. The animal treatments in agriculture or uses in aquaculture are not thought to
lead to significant post-application exposures.
Residential (homeowner) Adults: these individuals are members of the general population that
are exposed to chemicals by engaging in activities at their residences and also in areas not limited to
their residence (e.g., golf courses or parks) previously treated with a pesticide. These kinds of
exposures are attributable to a variety of activities and usually addressed by the Agency in risk
assessments by considering a representative activity that results in a conservative exposure calculation.
Residential Children: children are members of the general population that are exposed to
chemicals by engaging in activities in areas not limited to their residence (e.g., parks) previously treated
with a pesticide. These kinds of exposures are attributable to a variety of activities and usually
addressed by the Agency in risk assessments by considering a representative activity that results in a
conservative exposure calculation. Toddlers have been selected as the most sensitive exposure
population for the assessment.
The Agency's Standard Operating Procedures For Residential Exposure Assessment was
used to predict the amount of transferable residues available on treated turf because no chemical- and
scenario-specific data were available to complete this assessment. Special considerations were also
given to the methods of application in this assessment in order to account for the fact that the objective
of a mosquito control adulticide application (to create smaller droplets) is antithetical to a normal
agricultural application of a pesticide (to minimize drift). The Agency evaluated post-application
27
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residential risks by first calculating the amount of fenthion that deposits in areas after mosquito control
applications and then calculating the exposure to both adults and children in those environments. The
Agency used the Spray Drift Task Force model for predicting deposition from aerial applications (i.e.,
AgDRIFT) to determine how much material deposits in residential areas after aerial applications and
published data to determine how much material deposits in residential areas after ground-fogger
applications. After these values were determined, the risks for adults and toddlers were calculated
using guidance included in the Agency's Residential SOPs and guidance provided at the September 21,
1999 meeting of the FIFRA Science Advisory Panel on residential exposure issues.
At the FIFRA SAP meeting on September 21, 1999, several changes to the Residential SOPs
were proposed. The following proposed changes were incorporated into the fenthion exposure
assessment: The turf transferable residues were reduced from 20% to 5%; the turf transfer coefficient
was reduced from 43,000 cm2/hr (8,700 cm2/hr for kids) to 14,500 cm2/hr (5,200 cm2/hr for kids) per
hour when addressing short-term endpoints and 7,300 cm2/hr (2,600 cm2/hr for kids) per hour for
intermediate-term endpoints. Duration for both endpoints is 2 hours; the number of hand-to-mouth
events was changed from 1.56 events per hour x 350 cm2 (per event) to 20 events per hour x 20 cm2
(per event) - one hand-to-mouth event (20 cm2) represents the palmar surface area of 3 fingers; and
the percent of pesticide extracted from saliva was reduced from 100% to 50% extraction from the hand
by saliva.
The Agency considered both low exposure (e.g., light yard and garden work) and high exposure
(e.g., heavy yard work) activities for adults in the assessment. In order to consider the risks to children,
guidance from the Agency's SOPs For Residential Exposure Assessment was used to address the
exposures of children from treated turf.
Based on the anticipated fenthion use patterns and current labeling, four major post-application
exposure scenarios were modeled using a surrogate approach for each application method (i.e., aerial
and ground ULV). Two of these scenarios are assessment of exposure to adults while the remaining
two scenarios were assessments of exposures to toddlers. The four scenarios are:
(1) adults involved in a high exposure activity (e.g., heavy yard work) at the typical Florida mosquito
control application rate;
(2) adults involved in a high exposure activity (e.g., heavy yard work) at the label maximum mosquito
control application rate;
(3) toddlers involved in a high exposure activity (e.g., rolling/playing on lawn) at the typical Florida
mosquito control application rate; and
(4) toddlers involved in a high exposure activity (e.g., rolling/playing on lawn) at the label maximum
mosquito control application rate.
28
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The Agency believes that fenthion exposures can occur over a single day or up to weeks at a
time. This is supported by the length of time fenthion residues take to decline using the standard
dissipation model. The toxicology database for fenthion indicates that the Agency needs to separately
consider exposures to the skin and exposures via inhalation because the effects and the dose levels at
which effects occur differ based on whether it gets on skin or it is inhaled. However, inhalation
exposures are minimal in outdoor post-application scenarios because of the low vapor pressure and
because existing empirical data have also generally shown post-application inhalation exposures to be
negligible. As such, inhalation exposures are not considered in the post-application assessment. Hand-
to-mouth exposures are considered in this assessment because toddlers are anticipated to engage in
mouthing behaviors.
REIs are not considered a viable regulatory tool for reducing exposures and risks in the
residential environment (i.e., for the general population). Therefore, for chemicals used in the residential
environment or any other areas where the general population can be exposed, risk management
currently considers the risks associated with a chemical on the day it is applied and as part of an
aggregate exposure assessment (should the single day risks be of no concern.)
(2) Post-Application Residential Risk
Fenthion is used for wide area mosquito control in residential areas where exposure to adults and
children may occur. Exposure may result from performing yard work, and playing or performing other
recreational activities (e.g., golfing) on the treated areas. As a result, both toddler and adult risks were
considered in the risk assessment.
The use of a Restricted Entry Interval (REI) is not an appropriate method of risk mitigation for
residential use chemicals and, essentially, for all exposure scenarios where there is the potential for
unrestricted general population exposures. As a result, the approach used to evaluate residential risks
is to consider exposures immediately after application as these represent higher exposures and risks
which are a concern for acutely toxic compounds like the organophosphates.
The Agency developed exposure scenarios in this residential post-application risk assessment to
evaluate exposures to children and adults after both aerial and ground-based wide area mosquito
control applications. Different application methods were considered in the assessment because they
deposit different amounts of material in surrounding areas and the application rates (both allowable
maximum and average) are different for each method (i.e., resulting in different levels of exposure).
Risks to adults were assessed only via dermal exposures as outdoor post-application inhalation
exposures have been historically shown to be minimal and in this case the outdoor dilution factor is
expected to also minimize the potential for inhalation exposure. Adults are expected to have minimal
hand-to-mouth activity that would contribute to nondietary ingestion exposure. Dermal as well as
nondietary ingestion exposures to toddlers, however, were considered in this assessment to obtain total
risk estimates for aggregation purposes as toddlers are likely to be exposed from playing on treated
29
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lawns and from routine mouthing behaviors. Toddlers were selected as the most sentinel population for
this assessment because their exposures are expected to be higher than other children because they are
more mobile than younger children and they have a greater propensity for mouthing behaviors than
older children. In this assessment, the Agency considered hand-to-mouth behavior, object-to-mouth
behavior, and soil ingestion. All residential post-application risk calculations completed for adults and
children are presented in Appendix C of the ORE chapter.
There are no risk concerns for exposure of adults associated with any treatment scenario. The
combined MOEs for toddler exposures also do not exceed the Agency's level of concern for short-
term exposures; however, for intermediate-term exposures the MOE is 257 at the maximum aerial
application rate (where the Agency's level of concern is 300). MOEs for the intermediate-term
assessment were calculated using a dose level that was derived by taking the average of the dose levels
from applications occurring on a monthly basis. The MOE at the average application rate is 460 which
is not of concern.
4. Aggregate Risk
An aggregate risk assessment considers the combined risk from dietary exposure (food and
drinking water pathways) and residential exposure (dermal exposure, inhalation exposure for
homeowner applicators, and incidental oral exposure for toddlers from mouthing behavior). Aggregate
risk assessments for fenthion were conducted for acute (1-day), short-term (1-7 days), intermediate-
term (7 days to several months), and chronic (lifetime) exposure. Generally, all risks from these
exposures must have MOEs of greater than 100 to be not of concern to the Agency (for fenthion,
MOEs greater than 100 are not of concern for short-term exposures and MOEs greater than 300 are
not of concern for intermediate-term exposures). Results of the aggregate risk assessment are
summarized here.
a. Acute Aggregate Exposure and Risk
The Agency is able to quantitate the food sources of dietary exposure and residential exposure;
dietary exposure through drinking water has only been estimated using models. Acute dietary (food
only) risks exceed the Agency's level of concern as the most exposed population subgroup, children (1-
6 years), has a risk that is 800% of the aPAD based on very conservative exposure estimates. Based
on EECs generated via modeling, the potential exists for relatively small additional contributions to the
acute aggregate risk from surface water sources of drinking water in Florida. Thus, there is a concern
for acute aggregate risk due to fenthion use.
b. Aggregate Short-term and Intermediate-term Exposures and Risks
There are food and water sources of dietary exposure as well as residential exposures to fenthion
based on the current use pattern. Chronic dietary risk from food sources exceeds the Agency's level of
concern with the most highly exposed population subgroup, again, being children (1-6 years) at 270%
30
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of the cPAD. Drinking water sources could possibly contribute comparatively small levels of additional
dietary exposure and, hence, risk in Florida. Combined residential dermal and nondietary ingestion
exposures following aerial mosquito adulticide treatments result in intermediate-term risks of concern to
toddlers. The Agency is therefore, concerned about intermediate-term aggregate risk associated with
theuseoffenthion.
c. Chronic Aggregate Exposure and Risk
In the case of chronic aggregate risk, the Agency is able to quantitate only the food sources of
dietary exposure as the drinking water residues were estimated from conservative, screening-level
models. In the case of the dietary component (food only) of the chronic aggregate assessment, risks
were above the Agency's level of concern with the most highly exposed population subgroup, again,
being children (1-6 years) at 270% of the cPAD; these risk values were based on highly conservative
exposure estimates. Again, based upon conservative modeling, the potential exists for comparatively
small amounts of additional dietary exposure via drinking water. Thus, there is concern for chronic
aggregate risk resulting from fenthion use.
B. Environmental Risk Assessment
A summary of the Agency's environmental risk assessment is presented below. For detailed
discussions of all aspects of the environmental risk assessment, see the Environmental Fate and Effects
Division chapter, dated May 1, 1996 and the addendum dated July 31, 1996, available in the public
docket.
1. Environmental Fate and Transport
The environmental fate data base is incomplete; however, it is clear that fenthion degrades by
aerobic microbial metabolism with calculated half-lives of <1 day in an aerobic soil metabolism study
and 11 days under anaerobic aquatic conditions. Major degradates were fenthion sulfoxide, 3-methyl-
4-methylsulfonyl) phenol, fenthion phenol sulfoxide, fenthion phenol, and 3-methoyl phenol. In both
studies, carbon dioxide was a major degradate at the end of the studies.
Although no clear degradation rates are available, fenthion also probably degrades by photolysis
in water. Several studies that are unacceptable for various reasons have been submitted; all these
flawed studies indicate rapid degradation (half-lives of 1-4 hours) when irradiated with undescribed
artificial light sources.
No mobility studies with unaged fenthion have been submitted; however, since fenthion degrades
rapidly and thermal fogs and ULV are the only terrestrial uses of fenthion, there probably would be no
serious groundwater contamination from the parent compound. The aged column leaching studies
showed that fenthion residues (aged 30 days and leached 45 days) were mobile through the column.
31
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Fenthion sulfoxide, fenthion sulfone, fenthion phenol, 3-methoyl-4-methylsulfonyl) phenol, were all
recovered from the leachate. From information on other organophosphate insecticides we know that
the sulfoxide and sulfone compounds are often very toxic. It is not clear if the fenthion degradates are
biologically active, but if they are found to be of lexicological concern, further groundwater/drinking
water concerns may be evident.
Fenthion has an octanol water partition coefficient of 69,000, which indicates that it may
bioaccumulate in fish and non-target organisms. The laboratory accumulation study in fish indicates that
carp exposed to fenthion at 0.01 and 0.1 ppm had bioconcentration factors of approximately 2000x
and 2300x, respectively. Depuration occurred with approximately 95% of the residues depurating
during 15 days. The study was unacceptable because the results did not distinguish whether the parent
or the degradates bioaccumulated and whether the accumulations were in edible or visceral tissues.
2. Risk to Birds and Mammals
a. Birds - Mosquito Adulticide Applications
The potential for acute dietary risk to birds is high at the maximum aerial use rate of 0.1 Ib
ai/acre. The potential for acute dietary risk to endangered species is high at both the ground and aerial
maximum use rates of 0.03 and 0.1 Ib ai/acre, respectively. A chronic risk assessment for birds from
use of fenthion for mosquito control cannot be completed until chronic toxicity data are submitted.
Published literature and incident reports indicate that spray applications of fenthion present a
more serious threat to birds than indicated solely by dietary risk presumptions. The Agency's risk
presumptions assume that exposure from spray applications is primarily via ingestion of contaminated
food sources (e.g., grass, seeds, insects). However, dermal contact with aerial droplets and
contaminated vegetation and inhalation of ULV or thermal-fog mists also are likely routes of exposure
for birds. Fenthion is very highly toxic to birds dermally. Fenthion applied aerially by ULV spray is
used for lethal control of massive numbers of red-billed quelea (Quelea queled) in Africa, albeit at
much higher rates than are used for mosquito control in the U.S. The mortality that results from quelea
flying through the ULV spray mist is presumed to be due to both dermal contact and inhalation.
Secondary exposure of raptors feeding on dead, exposed birds also is a concern.
Several bird mortality incidents were reported during the 1970's and 1980's resulting from
fenthion spraying for mosquito control at single application rates comparable to those currently used. A
detailed account of the incidents can be found in the EFED chapter and the addendum to the EFED
chapter referred to above.
The US Fish and Wildlife Service (FWS) recently informed OPP of bird kills caused by fenthion
sprays for adult mosquito control on Marco Island, Collier County, Florida. FWS reported that dead
and/or sick birds were found on at least 12 occasions between October, 1998, and August, 1999. The
32
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incidents occurred after aerial (helicopter) ULV application of Baytex at a rate of 2/3 ounce of Baytex
(0.05 Ib ai) per acre, which conforms to the label application rate for aerial spraying. According to
FWS, sprays were made over the beach early in the morning, and sick and dead birds were observed
on the beach within 8-10 hours.
The FWS reports mortality of at least 16 bird species. All are listed migratory species (50 Code
of Federal Regulations 10.13 lists those species protected by the Migratory Bird Treaty Act) and one,
a piping plover (Charadrius melodus) is a Federally listed endangered species (50 Code of Federal
Regulations 17.1 l(h)} pursuant to the Endangered Species Act. More than 200 dead or sick birds
have been found, and it is possible that many more were effected but never found or reported. Other
species involved include western sandpiper (Calidris mauri), least sandpiper (C. minutilla), dunlin (C.
alpina), sanderling (C. alba), short-billed dowitcher (Limnodromus griseus), willet (Catoptrophoms
semipalmatus\ snowy plover (Charadrius alexandrinus), snowy egret (Egretta thula), little blue
heron (E. caeruled), cattle egret (Bubulcus ibis), black skimmer (Rhynchops nigef), sandwich tern
(Sterna sandvicensis), fish crow (Cyanocitta cristata), ring-billed gull (Larus delawarensis),
laughing gull (L. atricilla), and others not identified. A sample of dead shorebirds was sent to the
National Forensics Laboratory in Ashland, Oregon for analysis, and fenthion was detected on legs,
feathers, beaks and/or in stomach contents.
The situation on Marco Island appears to be somewhat unique. However, repeated sprays of
adulticide, principally fenthion, are made on Marco Island because of the continual influx of mosquitoes
from the Everglades (where larvicides cannot be applied). Because of the small area involved on
Marco Island, application is made by helicopter. The Collier County Mosquito District stated that they
sprayed on Marco Island about 175 days during the past three years. In contrast, Lee County mostly
sprays larvicides; fenthion is sprayed only occasionally and only in residential areas.
Marco Island is a haven for shorebirds. Parts of the shoreline include Florida Designated
Shorebird Nesting Area Critical Habitat. The shoreline currently is being considered for Federal
designation as Critical Habitat for wintering piping plover, which may be present eight months of the
year. Clearly, mitigation measures are needed to eliminate exposure of shorebirds to fenthion to ensure
their protection under the Endangered Species Act and the Migratory Bird Treaty Act.
Insectivorous passerines also are potentially at risk from exposure to fenthion. Tiebout and
Brugger (1995) assessed dietary risks of fenthion, naled, and malathion mosquito sprays to birds in
Florida. Based solely on ingestion of fenthion-contaminated food, they concluded that insectivorous
birds, including as many as 80 passerine species, could be at risk from fenthion applied for mosquito
control. A case study for the black-whiskered vireo (Vireo altiloquus barbatulus), a species
potentially at risk where mosquitoes are controlled in Florida, indicated that 42% of the population
could be at risk from a single fenthion application of 0.1 Ib ai per acre. In contrast, they predicted that
very few species would be at risk from naled and malathion, two alternative adulticide sprays.
33
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Based on the available information and the current incidents in Collier County, the Agency
concludes that fenthion spraying, especially when repeated at frequent intervals, may cause mortality in
a variety of bird species. Fenthion also is very highly toxic to estuarine invertebrates, which may be at
risk from mosquito spraying and may indirectly impact birds by reducing their food supply. The
Agency also is concerned about possible reproductive risks to birds exposed to repeated applications
of fenthion during and immediately preceding the breeding season. Avian reproduction tests (guidelines
71-4 a, b) are needed to determine if chronic exposure from repeat applications poses a reproductive
risk to birds.
b. Birds - Livestock Application
The Agency currently has no method for quantifying exposure to birds from applying a pesticide
on livestock. It is possible that such application poses some risk to birds that perch on recently treated
livestock or consume contaminated hairs or invertebrates. Dermal contact with fenthion can
contaminate a bird's feet and feathers. Although the potential for exposure exists from treatment of
livestock, this use of fenthion probably poses the least risk to birds of the currently registered uses.
Currently, two bird kill incidences are presumed to be related to livestock use. Information on these
incidences can be found in the EFED chapter. Any risk to birds associated with the livestock use is
now eliminated with the cancellation of all livestock products.
c. Mammals
Fenthion poses low acute risk to mammals. The potential for chronic risk is slight; however,
because fenthion degrades rapidly in the environment, chronic exposure is unlikely.
3. Risk to Aquatic Species
a. Freshwater and Estuarine/Marine Fish - Mosquito Adulticide
Applications
Fenthion poses low acute and chronic risk to freshwater fish and estuarine/marine fish at either
aerial or ground maximum mosquito adulticide application rates.
b. Freshwater and Estuarine/Marine Invertebrates - Mosquito
Adulticide Applications
Potential for acute and chronic risk is high for freshwater invertebrates and estuarine/marine
invertebrates at maximum aerial and ground application rates of 0.1 and 0.03 Ib ai/acre; however, risk
to aquatic organisms cannot be adequately assessed until outstanding data are submitted. An acute
estuarine/marine mysid test is required for the two major degradates and the TEP.
34
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IV. Summary of Benefits Assessment
A. Background
Mosquito control in Florida is conducted by 50 mosquito control districts. The districts are
governmental agencies that monitor for the presence of mosquito larvae and adults and mosquito-borne
diseases. Districts justify their annual budget to an elected committee that is responsive to the public.
Pesticide applications are part of overall mosquito IPM programs that include source reduction, use of
biocontrol agents such as mosquitofish, public education, rotation of pesticides, and other control
methods. The Florida Coordinating Council on Mosquito Control, answering to the Florida Secretary
of Agriculture, coordinates matters involving districts and state conservation agencies.
Mosquito control has historically been necessary year-round in most Florida areas. During most
years, mosquito-borne disease incidences have not caused a public health emergency, but their
appearance has been cyclic and unpredictable. A few isolated cases of St. Louis encephalitis show up
annually, with a larger scale outbreak happening less frequently.
B. Disease and Vector Monitoring
Mosquito control is designed to maintain the mosquito population at a level where, if it should
begin vectoring a disease, it will have minimal impact on the human population. Vector populations and
diseases fluctuate depending on complex environmental and biological circumstances including weather
patterns and alternate host populations.
Pesticide applications by mosquito control districts are based on monitoring data. Monitoring is
performed on a continuous basis at strategic locations across a district. Monitoring includes trapping
and counting adult mosquitos, conducting "bite counts" at designated sampling locations by district
personnel, sampling and counting of mosquito larvae, reporting human and animal disease incidence,
conducting bioassays of trapped adult mosquitoes for diseases, searching for suitable breeding habitat
such as tire dumps or rain pools, and recording complaint calls from citizens. Monitoring is conducted
on a daily basis. Bite counts, an important monitoring tool, must reach 25 bites per minute before
treatment is undertaken.
Aerial and ground fenthion applications in a district are usually spot treatments corresponding to
specific sites where monitoring has shown thresholds have been exceeded. In most areas, preemptive
larval treatments prevent adult populations from developing. Large area blanket spraying of residential
areas are only done if a widespread problem exists, such as an epidemic of encephalitis or a mosquito
population explosion following a hurricane. The application interval would also correspond to need
indicated by monitoring. There are provisions to avoid spraying where sensitive individuals live and
where there are beekeepers or wildlife refuges. To avoid and record nontarget effects, most districts
maintain close communications with park and refuge managers. General announcements are made to
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the public before spraying commences and most districts maintain web pages for public education and
information.
C. Pests and Diseases Targeted by the Use of Fenthion
Florida has over 70 species of mosquitoes, only 10 of which are generally targeted. Targeted
species include potential and actual vectors of St. Louis Encephalitis, Venezuelan Equine Encephalitis,
Eastern Equine Encephalitis, Malaria, Yellow fever, West Nile Virus, and Dengue. There is a fair
probability that any of the above diseases may show up in the human population during any year.
In the early 20th century, malaria, yellow fever, and dengue were commonly spread by Florida
mosquitoes. It was in response to these problems that mosquito control districts were initially formed
and the work of the districts is credited with elimination of those diseases from Florida. The CDC has
reported that fenthion is particularly effective against salt marsh Aedes mosquitoes that vector
Venezuelan Equine Encephalitis and Culex nigripalpus that vectors St. Louis encephalitis.
The threat of the spread of mosquito-vectored diseases is particularly great in Florida because
the frost-free climate supports year-round mosquito populations. The last widespread epidemic of St.
Louis Encephalitis in Florida occurred in 1990, with 223 human cases and 11 deaths. Incidences of
malaria and dengue have been increasing in Central and South America. Dengue is regularly reported
from Puerto Rico and other Caribbean islands adjacent to Florida. While none of the 96 cases of
malaria reported from Florida in 1998 were from indigenous sources, there is a threat that local
mosquitoes will become infected and begin transmitting it. Because malaria microbes have recently
developed resistance to several antimalarial drugs, the hazards of malaria control once it is in the human
population have increased. Fifty cases of Eastern Equine Encephalitis have been recorded from Florida
in the last thirty years. This disease is of major concern because of its high mortality rate among
humans. Fenthion has been successfully used to reduce populations of the vectors of the above
diseases.
Two new problems have surfaced in the last several years that are cause for public health
concern in Florida: a new pest, the Asian tiger mosquito, that may be a vector for dengue and other
diseases, and a new disease, the West Nile Virus. While not yet detected in Florida, West Nile Virus
appears to be spreading southward from the northern states and may become established soon. The
vectors for West Nile Virus, including various Culex and Aedes species, are already present in Florida.
Fenthion has been used to successfully manage populations of the above vectors in Florida.
D. Usage of Fenthion
Table 6 gives the number of mosquito control districts that used fenthion from 1994 - 1998 and
the pounds of the active ingredient used.
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Table 6. Usage of Fenthion
Fiscal Year
1994
1995
1996
1997
1998
Districts Using Fenthion
Air
4
4
4
7
3
Ground
6
7
7
8
5
Pounds Active Ingredient
Air
59,000
43,000
150,000
70,000
66,000
Ground
19,000
30,000
61,000
46,000
33,000
Seven programs used fenthion in FY98. These were Lee*, Collier*, Osceola*, East Volusia,
Duval, Hillsborough, and Pasco (* aerial). During FY97, users were Collier*, Duval*, Lee*,
Osceola*, Pasco*, Pinellas*, Glades, Hillsborough, Indian River, and Saint Lucie (* aerial).
Malathion, naled, and fenthion are the only adulticides applied aerially in Florida. Aerial adulticiding
with fenthion is favored by districts because the targets mainly occur in areas without roads and
because more widespread vector populations can be covered more quickly than by ground equipment.
Fenthion is amenable to aerial application because it is not as corrosive to equipment as naled and
because the formulation is very effective at a lower rate than malathion. Several counties discontinued
using fenthion from FY97 to FY98 because of low populations of target mosquitoes, resistance buildup
in target populations in some areas, and cost (naled and malathion are less expensive). High usage
years corresponded with higher target populations during those years, in part. More pounds of active
ingredient of malathion and naled than fenthion are applied annually in Florida. Fenthion is typically
applied at lower than label rates for both ground and aerial ULV applications: at 0.02 Ib ai per acre
ground with a 0.03 Ib ai per acre maximum label rate and 0.06 Ib ai per acre aerial ULV with a 0.1 Ib
ai per acre maximum label rate. The maximum rate of 0.03 Ib ai per acre label rate is used for thermal
fogging. Most districts apply aerially using ULV. According to users, the maximum label rates are
sometimes necessary because they are beneficial if there is a severe outbreak over a very large area
which may include some resistant populations that are susceptible only to the highest rate.
E. Comparative Efficacy and Resistance Management
Fenthion is not the sole mosquito insecticide used in any district: all districts rotate adulticides to
target certain species and for resistance management. They also complement adulticide applications
with larvicides and other IPM techniques to make sure adulticides are judiciously applied. Fenthion is
considered to be critical in the product rotation to slow mosquito resistance. Additionally, districts
tailor ground and aerial spraying and the chemicals to be used to the locality to be sprayed.
The CDC stated that fenthion use is critical for Florida for management of malathion-resistant
mosquito species, including Culex nigripalpus. Fenthion is particularly effective against Aedes salt
marsh species which are important over a major area of the state. Malathion is considered to be
ineffective at controlling target species in the areas where fenthion is used. That means that if malathion
is substituted, it must be used at higher rates and applied more frequently to obtain the same level of
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control as is obtained with fenthion. It is notable that in some areas, Culex nigripalpus is also
resistant to fenthion. In those areas, naled or malathion is used. Because of resistance problems,
chlorpyrifos has not been used as an adulticide in Florida in recent years. Overall, fenthion is effective
for a broad range of pest species, is compatible with other control methods, and is largely accepted by
the Florida public. Fenthion and other OPs have the drawback of taking longer than pyrethroids to
knock down adults.
To fully appreciate the benefits of fenthion, it is necessary to consider the constraints of the
various alternatives. For aerial application, naled, while as effective as fenthion and without resistance
problems, has the constraint of being very corrosive to equipment and having a reputation for causing
eye irritation in bystanders. Thus districts with larger urban populations that require spraying, including
Collier, Duval, and Lee would favor fenthion over naled for that reason. Because fenthion may be
applied ULV at a low rate, large areas may be treated without refilling, saving wear on equipment and
exposure to loaders.
Considering pyrethroid and pyrethrin alternatives, for ground application, resmethrin is ineffective
against Aedes salt marsh mosquitoes. Permethrin, while effective, is more expensive than fenthion and
prohibited for aerial application in the state because of concerns over nontarget aquatic organisms.
Pyrethrins and sumithrin have the drawback of being significantly more expensive than fenthion. There
are no carbamate or other classes of adulticides.
While larvicides and pupicides are alternatives to fenthion, they can't be solely relied upon for
control because the habitats for some vectors, notably Culex nigripalpus and Aedes salt marsh
species, are too cryptic or too vast to be reliably treated. Bti, altosid, Bs, and temephos are larvicides
used and oil and monomolecular films are the pupicides used by Florida districts.
F. Estimation of Economic Impacts of Switching to Alternatives
During 1998, fenthion was the least expensive active ingredient to apply per acre (average of
aerial and ground). Loss of fenthion and replacement with current alternatives would cause increased
costs for both aerial and ground mosquito control. For FY97 aerial application, if fenthion were
replaced with malathion and naled in proportion to their current usage, overall cost of application would
have increased from $1.5 million to $1.8 million, or 16%. This may be an underestimate because aerial
applications are more expensive than ground, but aerial estimates alone were not available. Also,
benefits of fenthion with respect to naled may be underestimated because of the corrosiveness of naled.
A previous Agency estimate stated that cost of replacing equipment due to corrosion would be up to
$0.02/acre for aerial applications. For FY 1997-98 ground application, if fenthion were replaced with
naled, malathion, pyrethroids, and pyrethrins in proportion to their current usage, cost of application
would have increased from $2.17 million to $2.47 million, or 13%. This may be an overestimate
because costs of ground applications alone for fenthion were not available.
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The research and registration pipeline for new mosquito adulticides is fairly empty. Bendiocarb
was recently retained for five years for use as an adulticide, but no products are currently marketed for
that use. Spinosad has been suggested as an alternative larvicide, but there is currently no ongoing
research. The state of Florida, University of Florida, and USD A Agricultural Research Service, in
cooperation with various districts, maintain an active research program in Florida on application
technology, reducing effective rates, vector and disease ecology, and mitigating nontarget effects. The
rate reduction research through use of new calibrating devices, more sensitive adult monitoring, and
development of new spray nozzles shows promise in reducing usage and more accurate vector
population targeting.
G. Benefits Conclusions
When consulted, CDC stated that fenthion is critical for resistance management in Florida and for
control of the very important Aedes salt marsh species and Culex nigripalpus. CDC also mentioned
that fenthion is very important overseas as a larvicide in vector control programs; a use which could be
impacted by loss in the US. Considering that mosquito-vectored diseases are prevalent and increasing
throughout the subtropics and tropics, that much of Florida is subtropical, that vectors occur in Florida,
and that the vectored diseases have historically occurred in Florida, there is a high probability that large
outbreaks could occur without adequate mosquito control. Fenthion has been described by public
health authorities as one of the effective tools for controlling adult mosquitoes in Florida and in
controlling mosquito-vectored diseases in Florida. The Agency concludes that the current uses of
fenthion in Florida have a significant public health benefit.
V. Interim Determination of Reregistration Eligibility, Tolerance Reassessment, and Risk
Management
A. Determination of Interim Reregistration Eligibility
Section 4(g)(2)(A) of FIFRA calls for the Agency to determine, after submissions of relevant
data concerning an active ingredient, whether products containing the active ingredient are eligible for
reregistration. The Agency has previously identified and required the submission of the generic (i.e., an
active ingredient specific) data required to support reregistration of products containing fenthion as an
active ingredient.
The Agency has completed its assessment of the occupational and ecological risks associated
with the use of pesticides containing the active ingredient fenthion, as well as a fenthion-specific dietary
risk assessment that has not considered the cumulative effects of organophosphates as a class. Based
on a review of these data and public comments on the Agency's assessments for the active ingredient
fenthion, EPA has sufficient information on the human health and ecological effects of fenthion to make
interim decisions as part of the tolerance reassessment process under FFDCA and reregistration under
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FIFRA, as amended by FQPA. Appendix B identifies the generic data requirements that the Agency
reviewed as part of its interim determination of reregistration eligibility of fenthion, and lists the
submitted studies that the Agency found acceptable.
The data identified in Appendix B were sufficient to allow the Agency to assess the registered
uses of fenthion and to determine if fenthion can be used without resulting in unreasonable adverse
effects to humans and the environment. The Agency has determined that certain uses of fenthion
require mitigation of the risks associated with the exposure to fenthion. The Agency will conduct a
public process to identify the best ways to reduce the risks associated with fenthion exposure. This
process will include a public comment period and a stakeholder meeting. Following the conclusion of
this process, the Agency will make a final determination on the mitigation measures that must be
adopted in order for products containing fenthion to be eligible for reregistration. Further, it should be
understood that the Agency may take appropriate regulatory action, and/or require the submission of
additional data to support the registration of products containing fenthion, if new information comes to
the Agency's attention or if the data requirements for registration (or the guidelines for generating such
data) change.
Although the Agency has not yet completed its cumulative risk assessment for the
organophosphates, the Agency is issuing this interim assessment now in order to initiate a stakeholder
process to identify risk reduction measures that are necessary to support the continued use of fenthion.
Based on its current evaluation of fenthion alone, the Agency has determined that fenthion products
would present risks inconsistent with FIFRA.
At the time that a cumulative assessment is conducted, the Agency will address any outstanding
risk concerns. Because this is an interim RED, the Agency may take further actions, if warranted, to
finalize the reregistration eligibility decision for fenthion after assessing the cumulative risk of the
organophosphate class. Such an incremental approach to the reregistration process is consistent with
the Agency's goal of improving the transparency of the reregistration and tolerance reassessment
processes. By evaluating each organophosphate in turn and identifying appropriate risk reduction
measures, the Agency is addressing the risks from the organophosphates in as timely a manner as
possible.
Because all food uses for fenthion have been voluntarily cancelled, this reregistration eligibility
decision announces that all existing food residue tolerances for fenthion will be revoked.
If the Agency determines, before finalization of the RED, that any of the determinations described
in this interim RED are no longer appropriate, the Agency will pursue appropriate action, including but
not limited to, reconsideration of any portion of this interim RED.
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B. Summary of Phase 5 Comments and Responses
When making its interim reregistration decision, the Agency took into account all comments
received during Phase 5 of the OP Pilot Process. A mitigation proposal was received from Bayer
Corporation Agriculture Division; details of this proposal are discussed in the next section. Several
other comments on mitigation were also received from various mosquito control districts in Florida,
Louisiana, Illinois, and Mississippi, Florida Department of Agriculture & Consumer Services, Florida
Department of Environmental Protection, Florida Mosquito Control Association, American Mosquito
Control Association, Health Canada-Pest Management Regulatory Agency, American Bird
Conservancy, other bird conservation organizations, and private citizens. These comments in their
entirety are available in the public docket. A brief summary of the comments and the Agency response
is noted here.
1) Comment: Eighteen comments were received from the mosquito control community including the
American Mosquito Control Association, the Florida Mosquito Control Association, and various
mosquito control districts in Florida, Illinois, and Louisiana. Their comments focused on the benefits of
fenthion and the organophosphate pesticides for use in mosquito control. They emphasized the
importance of fenthion in controlling disease (i.e., public health), quality of life for citizens (i.e., nuisance
mosquitoes), integrated pest management, resistance management, the fact that there are few
alternatives, and that fenthion is safe and effective. They also stated that EPA and HHS must work
together on this issue as mandated by FQPA. They emphasized that the risk assessments were based
on modeling for agricultural situations which vary greatly from mosquito control applications. Some
comments indicated that the high use rate for fenthion is never used or needed; however, others indicted
that the high rate is necessary at times for effective control. They also stated that workers are
adequately protected if the personal protective equipment is worn as indicated on the current fenthion
label. Several mosquito control districts mentioned the fact that they are currently using and/or testing
the new high pressure nozzle technology which reduces deposition.
Response: The Agency understands that fenthion is very important in protecting the public from
mosquito borne diseases. FQPA requires EPA to weigh the risks of a public health pesticide against
the health risk of the disease to be controlled. The threat of spread of mosquito-vectored diseases is
particularly great in Florida because the large bodies of water and mild climate supports year-round
mosquito populations. Recognizing the importance of this chemical, the Agency has developed a
number of mitigation measures which it proposes in order to reduce the risks from the use of fenthion.
Because of the significance of this chemical, the Agency believes that an open stakeholder process is
necessary to discuss these measures and/or to develop other workable mitigation measures that
adequately protect those at risk. The Agency is planning to conduct a public comment and stakeholder
process to accomplish this objective.
It is true that the Agency has relied on worker exposure data from PHED, which is generally
used for agricultural situations. The Agency does not have worker exposure data which is specific to
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mosquito control applications. Because mosquito control applications vary greatly from agriculture type
situations, the Agency intends to require generic mixer/loader/applicator exposure data to be submitted
for all mosquito pesticide applications. These data requirements will be included in a generic DCI for
all mosquito pesticides.
The Agency acknowledges the fact that many mosquito control districts, universities, and others
are currently engaged in research and development regarding better mosquito control practices. The
Agency believes that this research plays a very important part in improving pesticide use practices;
further work in these areas is encouraged.
2) Comment: Three comments were received from the Florida Department of Agriculture &
Consumer Services. Two were from the Florida Coordinating Council on Mosquito Control and one
was from the Division of Agricultural Environmental Services. The Florida Department of
Environmental Protection also submitted a comment. These comments were similar in nature to the
comments discussed above under comment #1.
3) Comment: Health Canada - Pest Management Regulatory Agency
The Head of Health Re-evaluation Section commented on the use of the human study. "The
extent to which the human study can be utilized in the modification of the interspecies uncertainty factor
should be further considered. This study may be of limited value in the consideration of an acute
reference dose due to study limitations including the small group size, testing in one sex and the timing of
cholinesterase determinations (24 hours after dosing)."
She also commented on the recalculated dermal absorption factor as follows: "...further
consideration of the recalculated dermal absorption factor of 3% may be warranted, particularly given
the limitation of the rabbit model in assessing dermal toxicity of certain organophosphates. Additional
studies to consider include the acute oral and dermal toxicity studies in the rat and a study by
Christenson, 1990 (cited in the 1996 JMPR) which looked at effects of route (oral, dermal,
subcutaneous) on cholinesterase activity in the rat following acute administration. The dermal
absorption factor estimated from an alternate rabbit study (using the vehicle Cremaphor) was
discounted by EPA as the vehicle was thought to enhance dermal absorption and use patterns were
reported to be primarily ULV applications with the technical form. Dermal absorption from non-ULV
applications may also need to be considered in risk assessment."
Response: The Agency has made a decision not to use human data.
Regarding further consideration of the recalculated dermal absorption factor, the vast majority of
mosquito adulticide applications make use of very concentrated formulations and/or ULV equipment.
Also, Cremophor is rarely, if ever, used as an intentionally added inert in pesticide formulations. As a
result, the Agency is of the opinion that use of the technical material is preferable over fenthion plus
Cremophor in a dermal toxicity study. It was determined that rabbits are not an appropriate species
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upon which to base hazard endpoint selection because dermal toxicity may be underestimated.
However, the relative dermal vs. oral toxicity in the same species, even rabbits, is considered
scientifically supportable. There are no appropriate/comparable oral and dermal rat toxicity studies
upon which to derive a dermal absorption factor. As far as the W.R. Christenson (1990c) study is
concerned, the study summarized in the 1995 JMPR does not appear to be useful for quantitative
determination of a dermal absorption factor because RBC and brain cholinesterase were observed at
the same dose (LOAEL and NOAEL reported to be 25 and 5 mg/kg BW, respectively) regardless of
whether administration was via the oral or the dermal route. In other words, the study is useful only to
postulate the relative ease of absorption of fenthion administered by different routes based on the time
after administration of the single dose at which maximum cholinesterase inhibition occurred (24 hours
for oral and 4 days for dermal).
4) Comment: Bayer Corporation - Agriculture Division
Bayer commented that the larvicide products are registered by Amvac and that these products
have not been sold for at least 10 years. The technical product only allows for formulation into
products used to control adult mosquitoes. Amvac has requested voluntary cancellation of the granular
larvicide products. Bayer also reiterated that the Rid-A-Bird perch is cancelled; that no human flaggers
are involved in aerial adulticiding operations; and that Bayer will explicitly prohibit human flaggers on the
label. They stated that historical exposure monitoring (cholinesterase) conducted by mosquito control
districts does not indicate that any consequential occupational exposure occurs in mosquito adulticiding
operations. Bayer also indicated that they are open to further discussions on worker safety measures
with EPA and the users of fenthion.
Regarding dietary risk, Bayer stated that they believe that the residue estimates are greatly
exaggerated, and also that additional studies are needed to refine the assessment. Bayer stated that
they are currently evaluating the livestock uses and would like to meet with Agency personnel to discuss
possible options.
Regarding the non-dietary residential exposure, Bayer stated that the conservative nature of the
assumptions used in this screening type assessment are likely to overestimate exposure. This exposure
is unlikely to occur as mosquito applications are most often made shortly before dawn and after
sundown, when toddlers would not be expected to spend extended periods of time on lawns. Bayer
does not believe that the use of fenthion in adult mosquito control poses unacceptable risk to toddlers
from post application exposure. Bayer stated that they would like to meet with the Agency,
representatives from mosquito control district(s) in Florida, other interested states, and the Centers for
Disease Control (CDC) to discuss additional data requirements. They note that CDC has indicated
that they may be able to fund some of the studies necessary to support the reregistration of fenthion.
Lastly, Bayer emphasized the importance of fenthion in public heath programs and they indicated that
other states, including Louisiana, Georgia, Mississippi and California have expressed interest in using
fenthion in their public health programs.
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Response: Regarding the Amvac larvicide products, the Agency received a request for
voluntary cancellation of these products on March 10, 1999. This voluntary cancellation was published
in the Federal Register dated June 14, 2000. The Agency is requiring in this document, a label
modification which prohibits human Saggers as Mosquito Abatement Districts do use spotters in some
cases and their exposure would likely be similar to Saggers. After discussions with the Agency, Bayer
subsequently decided to propose a phased voluntary cancellation of the fenthion livestock products.
After consultations with the stakeholders, the Agency accepted this proposal which is outlined in the
risk mitigation section of this document. The Agency also believes that the risk assessment for non-
dietary exposures is conservative because of a lack of chemical-specific and scenario-specific data.
The Agency intends to issue a DCI for all mosquito pesticides to call in worker exposure data specific
for mosquito control operations and deposition and turf transferrable residue studies to better estimate
post-application residential risk. Two Stakeholder Conference Calls were held on May 16 and May
30, 2000 to discuss possible risk mitigation measures and additional data requirements for fenthion. As
stated earlier, a stakeholder process will be held to further discuss risk mitigation for fenthion. It is
unlikely at this time that the Agency would allow expansion of the use of fenthion based on the lack of
data mentioned above and also because of high toxicity and risk concerns to birds and aquatic
invertebrates.
5) Comment: Forty-four comments were received from bird conservation organizations including
Save Our American Raptors (SOAR), Cornell University, Soarin' Hawk Raptor Rehabilitation, Liberty
Prairie Conservancy, Black Canyon Audubon Society (Colorado), Agricultural Conservation Programs
San Antonio, American Bird Conservancy, WildCare Foundation - Wildlife Rehabilitation, and 35
private citizens.
These comments focused on the toxicity of fenthion to birds. Each commentor requests that the
Agency disallow further avicide registration proposals for fenthion, cancel pour-on and spot treatments
for livestock uses of fenthion, and restrict the mosquito adulticide use of fenthion to emergency use
status only.
Response: The "Rid-A-Bird" perch product was cancelled by the Agency in March 1999. The
Agency has no plans to register fenthion for this use in the future. The registrant for fenthion, Bayer, has
voluntarily cancelled the livestock uses of fenthion which will eliminate risk to birds that land on the
backs of cattle. The Agency has developed ecological risk mitigation proposals for fenthion as outlined
later in this section. Further risk mitigation for fenthion will be discussed during the comment and
stakeholder process.
6) Comment: American Bird Conservancy
In addition to the comment listed above, the American Bird Conservancy submitted a second
comment regarding the use of fenthion as a mosquito adulticide. Their comment stated the following:
concentrated monitoring efforts to search for bird kills after fenthion spraying have not been carried out
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in Florida; wildlife mortalities due to pesticides are extremely difficult to observe even when
experienced searchers are involved in the monitoring efforts; fenthion is highly toxic to birds used as an
adulticide at current usage rates; an independent risk assessment reveals that 42% of an insectivorous
passerine species population will suffer mortality when exposed to one application of fenthion during a
normal application for the control of mosquitoes; ultra low volume spraying leads to increased risk for
birds because smaller particles designed to be airborne for longer periods of time could result in
increased inhalation risks with ULV spraying and ULV spraying may result in unacceptable levels of
fenthion deposited in nearby streams, estuaries, ponds and marshes because of drift during and after
application; fenthion bioaccumulates in the fatty tissues of living organisms; the long-term, chronic
effects of fenthion on birds have not been adequately studied; the reproduction study with the red-wing
blackbirds (Powell 1984) does not adequately address avian reproduction concerns; fenthion is a poor
insecticide choice for the chemical management of resistance; and Florida ecosystems are critical to the
maintenance of health populations of vast numbers of resident and migratory birds. With these
comments, the American Bird Conservancy urged the EPA to consider a full cancellation of fenthion
due to its acute and chronic avian toxicity, its potential to bioaccumulate, a documented history of
wildlife kills, and the fact that less hazardous and more effective alternatives exist under present
conditions.
Response: The Agency was informed on August 2, 2000 by the US Fish and Wildlife Service
about bird kills caused by fenthion sprays for adult mosquito control on Marco Island, Collier County,
Florida. This information, along with information on other bird kills from the use of fenthion for adult
mosquito control, leads the Agency to believe that mitigation measures are needed to eliminate
exposure of shorebirds to fenthion to ensure their protection under the Endangered Species Act and the
Migratory Bird Treaty Act. In addition to these concerns, the Agency is also concerned about the risk
to workers who handle fenthion and to residents from post application exposure from the mosquito
adulticide use. The Agency has developed proposed mitigation measures which are outlined in this
document. Because of the importance of this chemical for public health, the Agency intends to hold a
comment and stakeholder process to further discuss mitigation measures.
C. Decision on Tolerance Reassessment
Based on a review of the generic data for the active ingredient fenthion, the Agency has sufficient
information to reassess tolerances for fenthion. Specific findings are discussed in the following section.
D. Regulatory Position
1. FQPA Assessment
a. "Risk Cup" Determination
As part of the FQPA tolerance reassessment process, EPA assessed the risks associated with
this organophosphate. The assessment was for this individual organophosphate, and does not attempt
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to fully reassess these tolerances as required under FQPA. FQPA requires the Agency to evaluate
food tolerances on the basis of cumulative risk from substances sharing a common mechanism of
toxicity, such as the toxicity expressed by the organophosphates through a common biochemical
interaction with the cholinesterase enzyme. The Agency will evaluate the cumulative risk posed by the
entire class of organophosphates once the methodology is developed and the policy concerning
cumulative assessments is resolved.
EPA has determined that risk from exposure to fenthion is not within its own "risk cup." In other
words, even if fenthion did not share a common mechanism of toxicity with other chemicals, EPA
would be able to conclude today that the tolerances for fenthion do not meet the FQPA safety
standards. In reaching this determination EPA has considered the available information on the special
sensitivity of infants and children, as well as the chronic and acute food exposure. An aggregate
assessment was conducted for exposures through food, residential uses, and drinking water. Results of
this aggregate assessment indicate that the human health risks from these combined exposures are not
within acceptable levels; that is, combined risks from all exposures to fenthion do not "fit" within the
individual risk cup. Therefore, the fenthion tolerances will be revoked based on a phased voluntary
cancellation of all food uses of fenthion.
b. Tolerance Summary
In the individual assessment, tolerances for residues of fenthion in/on livestock commodities [40
CFR §180.214] are presently expressed in terms of the combined residues of fenthion and its
cholinesterase-inhibiting metabolites.
The data that were available to evaluate the established tolerances for the livestock commodities
for fenthion required extrapolations which result in a very conservative dietary risk assessment.
Anticipated residues (ARs) for beef and milk were extrapolated from existing livestock dermal
treatment studies since no data were available at the maximum use rate and 21-day pre-slaughter
interval. These ARs are higher than current tolerance levels for cattle tissues. While these ARs
represent a best estimate using the limited data available, they are an overestimate. In order to refine
the risk, residue data are needed for cattle reflecting the maximum application rate and minimum PSI
(21 days). All types of treatments (including ear tag treatment) must be represented by adequate
residue data. In light of these data requirements, Bayer decided to voluntarily cancel the livestock uses
of fenthion. A detailed description of the phased voluntary cancellation can be found in section D. A
summary of the fenthion tolerance actions is outlined in Table 7.
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Table 7. Tolerance Summary for Fenthion.
Tolerances Listed Under 40 CFR §180.214
Commodity
Cattle, fat
Cattle, meat
Cattle, (mbyp)
Hogs, fat
Hogs, meat
Hogs, (mbyp)
Milk
Current Tolerance, ppm
0.1
0.1
0.1
0.1
0.1
0.1
0.01(N)
Tolerance Reassessment,
ppm
Revoke
Revoke
Revoke
Revoke
Revoke
Revoke
Revoke
Comment
Per voluntary cancellation
Per voluntary cancellation
Per voluntary cancellation
Per voluntary cancellation
Per voluntary cancellation
Per voluntary cancellation
Per voluntary cancellation
The Agency will commence proceedings to revoke the tolerances referred to above at the
appropriate time in relation to the phased voluntary cancellation request received from Bayer.
2. Endocrine Disrupter Effects
EPA is required under the FFDCA, as amended by FQPA, to develop a screening program to
determine whether certain substances (including all pesticide active and other ingredients) "may have an
effect in humans that is similar to an effect produced by a naturally occurring estrogen, or other such
endocrine effects as the Administrator may designate." Following the recommendations of its
Endocrine Disrupter Screening and Testing Advisory Committee (EDSTAC), EPA determined that
there were scientific bases for including, as part of the program, the androgen and thyroid hormone
systems, in addition to the estrogen hormone system. EPA also adopted EDSTAC's recommendation
that the Program include evaluations of potential effects in wildlife. For pesticide chemicals, EPA will
use FIFRA and, to the extent that effects in wildlife may help determine whether a substance may have
an effect in humans, FFDCA authority to require the wildlife evaluations. As the science develops and
resources allow, screening of additional hormone systems may be added to the Endocrine Disrupter
Screening Program (EDSP).
When the appropriate screening and/or testing protocols being considered under the Agency's
EDSP have been developed, fenthion may be subjected to additional screening and/or testing to better
characterize effects related to endocrine disruption.
3. Labels
No label amendments are necessary at this time. The Agency intends to hold a stakeholder
process to identify risk mitigation measures for fenthion.
47
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E. Regulatory Rationale
The following is a summary of the rationale and proposals for managing risks associated with the
current use of fenthion.
1. Risk Mitigation
a. Dietary Mitigation
(1) Acute and Chronic Dietary (Food)
Acute dietary risk from food exceeds the Agency's level of concern for the general U.S.
population and all population subgroups, including infants and children. A DEEM™ analysis yielded a
percent acute PAD value of 800% for the most highly exposed subgroup (children 1-6 years). The risk
falls below the Agency's level of concern between the 90th and 95th percentiles.
As discussed earlier, this risk assessment was based on limited data available at the time of the
risk assessment. In order to refine this risk assessment, further magnitude of residue studies in livestock
would be required. As a result, Bayer has submitted a request to voluntarily cancel all livestock uses of
fenthion. EPA contacted the USDA (APHIS) to inquire whether this cancellation would adversely
affect stakeholders (i.e., cattlemen, dairy farmers, etc...). USDA contacted various stakeholders and
determined that they would not be adversely affected because of the availability of registered
alternatives.
Bayer proposed a phased cancellation of their products, which the Agency has accepted. The
fenthion livestock products will be cancelled as follows in Table 8:
Table 8. Phased Voluntary Cancellation of Fenthion Livestock Products
Product Name
Spotton (Fenthion) Cattle Insecticide
20% Ready-To-Use
liguvon Brand of Fenthion Swine
Insecticide Pour-On
liguvon (fenthion) Technical Grade
100
Lysoff Pour-On
Cutter Blue Insecticide Cattle Ear Tag
EPA Registration Number
EPA Reg. No. 11556-37
EPA Reg. No. 11556-34
EPA Reg. No. 11556-36
EPA Reg. No. 11556-48
EPA Reg. No. 11556-105
Cancellation Date
October 2000 (30 day
comment period)
October 2000 (30 day
comment period)
12/31/2000 (30 day
comment period)
12/31/2000 (30 day
comment period)
12/31/2000 (30 day
comment period)
Existing Stocks
Provision
none
1 year from date
of cancellation
none
1 year from date
of cancellation
1 year from date
of cancellation
48
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(2) Drinking Water
As explained earlier in this document, the only potential dietary exposure via drinking water is
surface water in Florida as a result of the mosquito adulticide use; even then, exposure is expected to
be small because the application rate is low and because the key to controlling adult mosquitoes is
application such that minute fenthion droplets (generated via fogging or ultralow volume treatments)
remain airborne for as long as possible to increase the opportunity for droplets to contact a mosquito.
This application technique facilitates drift, reduces deposition, and widens the area of deposition. As a
means of estimating the relative magnitude of potential risk associated with fenlhion in drinking water
compared to food and residential sources, EECs were compared to the PADs. Modeled fenthion
exposure estimates due to drinking water alone (i.e., without considering food sources) indicate that
small amounts of the aPAD and the cPAD could be utilized by residues in drinking water alone. There
is little concern for adults and children from exposure to fenthion in drinking water because: (i) the
EECs utilized in these calculations were derived from conservative, screening-level models, and (ii) only
minor exposure to surface water is possible due to the application rate and method.
b. Public Comment and Stakeholder Meeting Process
Given the high toxicity of fenthion and potential risks posed to workers, residential bystanders,
birds, and aquatic invertebrates, the Agency has developed a number of mitigation measures which it
proposes in order to reduce the risks outlined in this document. However, since fenthion has significant
benefits and there are few if any viable alternatives, the Agency believes that it is important that a broad
stakeholder process be conducted to discuss these measures and/or to develop other workable
mitigation measures that adequately protect those at risk. Therefore, the Agency is planning to conduct
a public comment and stakeholder process to accomplish this objective.
During the public comment period, commencing with the publishing of a Federal Register Notice,
comments and suggestions will be collected and reviewed concerning the measures outlined in this
document. These revised mitigation measures will be discussed at a stakeholder meeting that will be
held within 9 months from the issuance of this interim RED at a location to be determined. For this
meeting to be most efficient and successful, all interested parties and viewpoints will be welcomed and
considered. Following the conclusion of this process, the Agency will make a final determination on the
mitigation measures it believes must be adopted in order for products containing fenthion to be eligible
for reregistration.
c. Proposed Risk Mitigation Measures
The following mitigation measures are proposed for the remaining fenthion products (i.e., the
mosquito adulticide and the aquaculture SLNs). These measures are to be discussed as part of the
public review and stakeholder meeting process mentioned above.
49
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(1) Occupational Risk Mitigation
(a) Mosquito Adulticide Use
For mosquito control adulticide applications, the Agency has concerns for mixers/loaders and
applicators for both aerial and ground applications of liquid formulations for mosquito adulticide
applications of fenthion.
Data Requirements: The Agency does not have worker exposure data which is specific to
mosquito applications. All analyses were completed using data from PHED which is generally used for
agricultural situations. Because mosquito applications vary greatly from agriculture type situations, the
Agency is requiring generic mixer/loader/applicator exposure data to be submitted for all mosquito
pesticide applications. These data requirements will be included in a generic DCI for all mosquito
pesticides. Medical monitoring studies will also be required in the mosquito pesticide DCI.
Proposed Risk Mitigation Measures:
Handlers must use closed systems only. The current labels give protective clothing
statements for both closed systems and non-closed systems. The Agency believes that
requiring closed systems for all types of mosquito control applications will result in less
exposure to workers.
Add a prohibition of human Saggers to the label. Bayer indicated in their Phase 5
comments that human Saggers are never used in mosquito control applications, but that
they would amend their labels by adding this prohibition.
• Change the use rate on the label to only allow the highest rate for public health use (i.e.,
when disease has been confirmed in mosquito traps and sentinel chickens). The typical
rates of 0.056 Ib ai/acre (aerial) and 0.03 Ib ai/acre (ground) or lower must be used.
These typical rates were based on data from various Florida mosquito control districts.
(b) Aquaculture Use
The Agency has concerns regarding the use of fenthion in aquaculture. In order to mitigate risk
to handlers in this occupational scenario, the Agency is proposing the elimination of the backpack
sprayer method of application. A handwand sprayer would be used.
(2) Post-Application Residential Risk Mitigation
There are no risk concerns for exposure of adults associated with any treatment scenario.
However, for intermediate-term toddler exposures the MOE is 257 at the maximum aerial application
rate (target level of concern is 300). Even though this number slightly exceeds the Agency's level of
concern, the Agency does not have serious concerns for this scenario because of the conservative
nature of the risk assessment and the fact that mosquito control districts in Florida rarely use the
50
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maximum use rate for fenthion. Generally, a lower typical rate is used. The intermediate-term MOE at
the lower (typical) application rate is 460.
Data Requirements. In order to further refine this risk assessment, chemical-specific deposition
and turf transferrable residue studies need to be submitted. These studies will be required in a generic
DCI for all mosquito control pesticides. A DNT study is also required for this chemical.
Proposed Risk Mitigation Measures
Change the use rate on the label to only allow the highest rate for public health use (i.e.,
when disease has been confirmed in mosquito traps and sentinel chickens). The typical
rates of 0.056 Ib ai/acre (aerial) and 0.03 Ib ai/acre (ground) or lower must be used.
These typical rates were based on data from various Florida mosquito control districts.
(3) Environmental Risk Mitigation
Ecological risks are of concern to the Agency. Fenthion is very highly toxic to birds and highly
toxic to estuarine/marine invertebrates. The mosquito adulticide use of fenthion has been implicated in
several bird kill incidents, including recent bird kills on Marco Island, Florida. These kills on Marco
Island are currently under investigation by the US Fish and Wildlife Service.
Data Requirements. Avian reproduction studies with the northern bobwhite and the mallard are
required. Three acute toxicity studies with the mysid shrimp are required: 1 using a formulation, 1 using
the sulfoxide degradate, and 1 using the sulfone degradate. Additional environmental fate data are not
required. The available data is adequate to assess the risk to fenthion. Additional data would not alter
the risk picture.
Proposed Risk Mitigation Measures
• Restrict the use of fenthion to mosquito control districts in Florida that have developed a
plan to identify critical/sensitive bird habitats and endangered species in their counties and
have addressed ways to avoid exposure to those areas.
• Change the use rate on the label to only allow the highest rate for public health use (i.e.,
when disease has been confirmed in mosquito traps and sentinel chickens). The typical
rates of 0.056 Ib ai/acre (aerial) and 0.03 Ib ai/acre (ground) or lower must be used.
These typical rates were based on data from various Florida mosquito control districts.
• Require buffer zones to protect aquatic organisms, especially invertebrates.
• Require certain label changes to improve applications and lessen risk to non-target
organisms.
F. Other Labeling
In order to remain eligible for reregistration, other use and safety information need to be placed
on the labeling of all end-use products containing fenthion. Because the Agency intends to hold a
51
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stakeholder process in the near future to identify risk mitigation measures for fenthion, any necessary
label changes will be made after the stakeholder process has taken place. No label amendments are
necessary at this time.
1. Endangered Species Statement
The Agency has developed The Endangered Species Protection Program to identify pesticides
whose use may cause adverse impacts on endangered and threatened species, and to implement
mitigation measures that will eliminate the adverse impacts. At present, the program is being
implemented on an interim basis as described in a. Federal Register notice (54 FR 27984-28008, July
3, 1989), and is providing information to pesticide users to help them protect these species on a
voluntary basis. As currently planned, but subject to change as the final program is developed, the final
program will call for label modifications referring to required limitations on pesticides uses, typically as
depicted in county-specific bulletins or by other site-specific mechanisms as specified by state partners.
A final program, which may be altered from the interim program, will be described in a future Federal
Register notice. The Agency is not imposing label modifications at this time through the IRED. Rather,
any requirements for product use modification will occur in the future under the Endangered Species
Protection Program.
2. Spray Drift Management
The Agency has been working with the Spray Drift Task Force, EPA Regional Offices and State
Lead Agencies for pesticide regulation and other parties to develop the best spray drift management
practices. The Agency is proposing interim mitigation measures for aerial applications that should be
placed on product labels/labeling as specified in section V of this document. The Agency has
completed its evaluation of the new data base submitted by the Spray Drift Task Force, a membership
of U.S. pesticide registrants, and is developing a policy on how to appropriately apply the data and the
AgDRIFT computer model to its risk assessments for pesticides applied by air, orchard airblast and
ground hydraulic methods. After the policy is in place, the Agency may impose further refinements in
spray drift management practices to reduce off-target drift and risks associated with aerial as well as
other application types where appropriate. In the interim, labels should be amended to include the
following spray drift related language.
For products that are applied outdoors in liquid sprays (except mosquito adulticides), regardless
of application method, the following must be added to the labels:
"Do not allow this product to drift"
52
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VI. What Registrants Need to Do
A. Manufacturing Use Products
1. Additional Generic Data Requirements
The generic data base supporting the reregistration of fenthion for the above eligible uses has
been reviewed and determined to be substantially complete. The following data gaps remain:
Avian reproduction studies with the northern bobwhite and the mallard are required. Three acute
toxicity studies with the mysid shrimp are required: 1 using a formulation, 1 using the sulfoxide
degradate, and 1 using the sulfone degradate.
A mosquito pesticide worker exposure DCI will be issued in the near future for all mosquito
pesticides. This DCI will also include post-application bystander data requirements such as deposition
studies and turf transferable residue studies.
Also, a Data Call-In Notice (DCI) was recently sent to registrants of organophosphate
pesticides currently registered under FIFRA (August 6, 1999 64FR42945-42947, August 18
64FR44922-44923). DCI requirements included acute, subchronic, and developmental neurotoxicity
studies; due dates are 9/2001. The developmental neurotoxicity study is required for fenthion because
it is used as a wide area mosquito adulticide which results in residential exposure.
2. Labeling for Manufacturing Use Products
Because the Agency intends to hold a public stakeholder meeting to determine the best ways to
reduce risks associated with the use of fenthion, the registrant does not need to submit applications for
amended registration at this time.
B. End-Use Products
1. Additional Product-Specific Data Requirements
Section 4(g)(2)(B) of FIFRA calls for the Agency to obtain any needed product-specific data
regarding the pesticide after a determination of eligibility has been made. Registrants must review
previous data submissions to ensure that they meet current EPA acceptance criteria and if not, commit
to conduct new studies. If a registrant believes that previously submitted data meet current testing
standards, then the study MRID numbers should be cited according to the instructions in the
Requirement Status and Registrants Response Form provided for each product.
53
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A product-specific data call-in, outlining specific data requirements, accompanies this interim
RED.
2. Labeling for End-Use Products
Because the Agency intends to hold a public stakeholder meeting to determine the best ways to
reduce risks associated with the use of fenthion, the registrant does not need to submit applications for
amended registration at this time.
C. Existing Stocks
The registrant may distribute and sell the livestock products according to Table 8 in Section V of
this document which was based upon the registrant's proposed phased cancellation of these products
which the Agency has accepted.
No existing stocks provisions are necessary for the remaining fenthion products because no label
changes are necessary at this time.
D. Labeling Changes Summary Table
No labeling changes are necessary at this time. The Agency will conduct a public stakeholder
meeting in the near future to identify the best ways to reduce the risks associated with fenthion
exposure.
VI. Related Documents and How to Access Them
This interim Reregistration Eligibility Document is supported by documents that are presently
maintained in the OPP docket. The OPP docket is located in Room 119, Crystal Mall #2, 1921
Jefferson Davis Highway, Arlington, VA. It is open Monday through Friday, excluding legal holidays
from 8:30 am to 4 pm.
The docket initially contained preliminary risk assessments and related documents as of [date].
Sixty days later the first public comment period closed. The EPA then considered comments, revised
the risk assessment, and added the formal "Response to Comments" document and the revised risk
assessment to the docket on [date].
All documents, in hard copy form, may be viewed in the OPP docket room or downloaded or
viewed via the Internet at the following site: "http://www.epa.gov/pesticides/op."
54
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VH. APPENDICES
55
-------
56
-------
Appendix A. Currently Registered Use Patterns for Reregistration
Application Site
Application Type
Application Equipment
AIRCRAFT
APPLICATION
Mosquitoes (Adults
Only) (Florida Only)
AIRCRAFT
APPLICATION
Mosquitoes (Adults
Only) (Florida Only)
INSECT GROUND
APPLICATION
Mosquitoes (Adults
Only) (Florida Only)
Formulation
95% Soluble
Concentrate
[3125-148]
95% Soluble
Concentrate
[3125-148]
95% Soluble
C oncentrate
ro 1 'N C 1/1 O1
J Iz j-14o
Single
Application
Rate
0.66-1.3
Fluid Ounces
0.4
Fluid Ounces
0.03 Ibs
Per Acre
Use Directions and Limitations
Ultra Low Volume Spray: For cotnrol of mosquito adults, BAYTEX Liquid concentrate may be applied
undiluted in any aircraft equipment that has been adapted and calibrated for applying ultra low volumes of
spray material.
Applied specified dosage (0.05 to 0.1 Ib active ingredient) per acre using the liquid concentrate in undiluted
form with aircraft equipment capable of applying the proper volume per acre.
Use lower rate when applying to open non-canopied areas; use higher rate when applications are made in areas
[laving a vegatation canopy.
No more than 5% of the droplets should exceed 80 MMD.
Thermal Fog: For control of mosquito adults apply specified dosage (0.03 Ib active ingredient) per acre using
the product mixed in 0.2 to 0.8 quarts of oil per acre. Apply as a thermal fog by injecting solution into FAA
approved engine exhaust system. Repeat applications as necessary.
Ground ULV Concentrate Application: Applications may be made in residential areas, municipalities, tidal
marshes, swamps and woodlands. Do not apply to any agricultural crops. Apply undiluted BAYTEX Liquid
Concentrate at the rate of 1 .2 fluid ounce/minute at 5 mph; 2.4 fluid ounce/minute at 10 mph and 3.6 fluid
ounce/minute at 15 mph; applying a 300-foot swath. These flow rates are equivalent to 0.03 pounds active
ingredient per acre.
CAUTION - SPECIAL INSTRUCTIONS: This application can be made only under the following conditions:
(1 ) Application in calm air conditions is to be avoided. (2) Application is not to be made in the immediate
vicinity of pedestrians. (3) Vehicles used to apply must be air conditioned, or equipped with automatic speed
control flow device. SEE NOTE.
57
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Application Site
Application Type
Application Equipment
Formulation
Single
Application
Rate
Use Directions and Limitations
INSECT GROUND
APPLICATION
Dragonfly Larvae
Only
(Arkansas, Florida,
Missouri Only)
95% Soluble
Concentrate
[3125-148)
0.5
Fluid Ounces
Aquaculture Treatments: Special Local Needs to control larval dragonflies in commerically operated
freshwater ponds prior to stocking ornamental fish such as koi carp, goldfish, comets, shubunkins, fantails and
baitfish such as shiners and minnows.
Applied 0.5 ounces of BAYTEX Liquid Concentrate per 40,000 gallon pond, resulting in a aquatic
concentration of 0.1 ppm ai. The material is applied by handheld equipment and is made by diluting the
appropriate amount of BAYTEX with water at the rate of 1 ounce of BAYTEX per gallon water and distribution
uniformly over the pond.
Single applications are allowed 2 to 4 days prior to stocking.
No discharge of ponds can be made within 7 days of treatment.
This is a "restricted use" application and must be made by a certified applicator or a person under their direct
supervision.
58
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Appendix B. Table of Generic Data Requirements and Studies Used to Make the
Reregistration Decision
GUIDE TO APPENDIX B
Appendix B contains listing of data requirements which support the reregistration for active
ingredients within the case Fenthion covered by this interim RED. It contains generic data requirements that
apply Fenthion in all products, including data requirements for which a "typical formulation" is the test
substance.
The data table is organized in the following formats:
1. Data Requirement (Column 1). The data requirements are listed in the order in which they
appear in 40 CFR part 158. The reference numbers accompanying each test refer to the
test protocols set in the Pesticide Assessment Guidance, which are available from the
National Technical Information Service, 5285 Port Royal Road, Springfield, VA 22161
(703)487-4650.
2. Use Pattern (Column 2). This column indicates the use patterns for which the data
requirements apply. The following letter designations are used for the given use patterns.
A. Terrestrial food
B. Terrestrial feed
C. Terrestrial non-food
D. Aquatic food
E. Aquatic non-food outdoor
F. Aquatic non-food industrial
G. Aquatic non-food residential
H. Greenhouse food
I. Greenhouse non-food
J. Forestry
K. Residential
L. Indoor food
M. Indoor non-food
N. Indoor medical
O. Indoor residential
3. Bibliographic Citation (Column 3). If the Agency has acceptable data in its files, this column
list the identify number of each study. This normally is the Master Record Identification
(MIRD) number, but may be a "GS" number if no MRID number has been assigned. Refer
to the bibliography appendix for a complete citation of the study.
59
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Data Supporting Guideline Requirements for the Reregistration of Fenthion
REQUIREMENT
USE PATTERN
CITATION(S)
PRODUCT CHEMISTRY
61-1
Chemical Identity
61 -2 A Start. Mat. & Mnfg. Process
61-2B Formation of Impurities
62-1 Preliminary Analysis
62-2 Certification of limits
62-3 Analytical Method
63-2 Color
63-3 Physical State
63-4 Odor
63-5 Melting Point
63-6 Boiling Point
63-7 Density
63-8 Solubility
63-9 Vapor Pressure
63-10 Dissociation Constant
63-11 Octanol/Water Partition
63-12 pH
63-13 Stability
63-17 Storage stability
ECOLOGICAL EFFECTS
71 -1A Acute Avian Oral - Quail/Duck
71 -1B Acute Avian Oral - Quail/Duck TEP
71 -2 A Avian Dietary - Quail
71-2B Avian Dietary - Duck
ALL
ALL
ALL
ALL
ALL
ALL
ALL
ALL
ALL
ALL
ALL
ALL
ALL
ALL
ALL
ALL
ALL
ALL
ALL
A,C,E
A,C,E
A,C,E
A,C,E
40085801, 40223002, 41026101,
42167901, 42167903
40085801, 41026101, 42167901,
42167903
40085801, 41026101, 42167901,
42167903
40223001, 41026101, 42167902
41026101, 40223001, 42167902,
41026103
41026101, 40223001, 42167902,
41026104
40085802
40085802
40085802
40085802
40085802
40085802
40085802
40085802 (data gap - upgradable)
40085802
40085802 (data gap - upgradable)
40085802
40085802
41026102, 41026105, 104232,
115899,115931, 115935, 159021
40186701,41171701
40186701,41171701
40186702
40186703
60
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Data Supporting Guideline Requirements for the Reregistration of Fenthion
REQUIREMENT
71-3
7 1-4 A
71-4B
71-5A
71-5B
72-1 A
72-1B
72- 1C
72-1D
72-2A
72-2B
72-3A
72-3B
72-3 C
72-3D
72-3E
72-3F
72-4A
72-4B
72-5
72-6
72-7A
72-7B
Wild Mammal Toxicity
Avian Reproduction - Quail
Avian Reproduction - Duck
Simulated Field Study
Actual Field Study
Fish Toxicity Bluegill
Fish Toxicity Bluegill - TEP
Fish Toxicity Rainbow Trout
Fish Toxicity Rainbow Trout- TEP
Invertebrate Toxicity
Invertebrate Toxicity - TEP
Estuarine/Marine Toxicity - Fish
Estuarine/Marine Toxicity - Mollusk
Estuarine/Marine Toxicity - Shrimp
Estuarine/Marine Toxicity Fish- TEP
Estuarine/Marine Toxicity Mollusk -
TEP
Estuarine/Marine Toxicity Shrimp -
TEP
Early Life Stage Fish
Life Cycle Invertebrate
Life Cycle Fish
Aquatic Organism Accumulation
Simulated Field - Aquatic Organisms
Actual Field - Aquatic Organisms
USE PATTERN CITATION(S)
A,C,E
A,C,E
A,C,E
A,C,E
A,C,E
A,C,E
A,C,E
A,C,E
A,C,E
A,C,E
A,C,E
A,C,E
A,C,E
A,C,E
ACE
J-L,^,-L-,
A,C,E
A,C,E
A,C,E
A,C,E
A,C,E
A,C,E
A,C,E
A,C,E
reserved
data gap
data gap
waived
waived
40274101
40856102
40214201
40856102
40246401
reserved
40495501
40564101, 40879401
data gap
40856106
40856105
40856110
40564102
40871401
reserved
reserved
waived
waived
TOXICOLOGY
81-1
81-2
81-3
Acute Oral Toxicity - Rat
Acute Dermal Toxicity - Rabbit/Rat
Acute Inhalation Toxicity - Rat
A,C,E
A,C,E
A,C,E
40186704
40186705
40186706
61
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Data Supporting Guideline Requirements for the Reregistration of Fenthion
REQUIREMENT
81-4
81-5
81-6
81-7
81-8
82-1A
82-1B
82-2
82-4
82-7
82-5A
83-1A
83-1B
83 -2 A
83-2B
83-3A
83-3B
83-4
84-2A
84-2B
85-1
Primary Eye Irritation - Rabbit
Primary Dermal Irritation - Rabbit
Dermal Sensitization - Guinea Pig
Acute Delayed Neurotoxicity - Hen
Neurotoxicity - Rats
90-Day Feeding - Rodent
90-Day Feeding - Non-rodent
21 -Day Dermal - Rabbit/Rat
90-Day Inhalation - Rat
Subchronic Neurotoxicity - Rats
90-Day Neurotoxicity - Hen
Chronic Feeding Toxiciry - Rodent
Chronic Feeding Toxicity - Non-
Rodent
Oncogenicity - Rat
Oncogeniciry - Mouse
Developmental Toxiciry - Rat
Developmental Toxiciry - Rabbit
2-Generation Reproduction - Rat
Gene Mutation (Ames Test)
Structural Chromosomal Aberration
General Metabolism
USE PATTERN CITATION(S)
A,C,E
A,C,E
A,C,E
A,C,E
A,C,E
A,C,E
A,C,E
A,C,E
A,C,E
A,C,E
A,C,E
A,C,E
A,C,E
A,C,E
A,C,E
A,C,E
A,C,E
A,C,E
A,C,E
A,C,E
A,C,E
40186708
40186709
40186710
41283401,41283402
44326401
waived
waived
40329501, 40808601
waived
44339401
40933601,43121401
42699902, 42457201, 41743101,
41103701,40327001
42901402, 4269901, 41632801,
40341701
42699902, 42457201, 41743101,
00147478
42901403, 42759701, 41869201,
00147478
40329401
40462701
42901401,41348601
41283404
41283403
00115926, 00116396, 00132309,
00154967
ENVIRONMENTAL FATE
161-1
161-2
161-3
161-4
Hydrolysis
Photodegradation - Water
Photodegradation - Soil
Photodegradation - Air
A,C,E
A,C,E
A,C,E
A,C,E
Mobay Report No. 49130
40110401
inapplicable
reserved
62
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Data Supporting Guideline Requirements for the Reregistration of Fenthion
REQUIREMENT
162-1
162-2
162-3
162-4
163-1
163-2
163-3
164-1
164-2
164-3
164-5
165-1
165-2
165-3
165-4
165-5
RESIDl
171-4A
171-4B
171-4C
171-4D
Aerobic Soil Metabolism
Anaerobic Soil Metabolism
Anaerobic Aquatic Metabolism
Aerobic Aquatic Metabolism
Leaching/ Adsorption/Desorption
Volatility - Lab
Volatility - Field
Terrestrial Field Dissipation
Aquatic Field Dissipation
Forest Field Dissipation
Long Term Soil Dissipation
Confined Rotational Crop
Field Rotational Crop
Accumulation - Irrigated Crop
Bioaccumulation in Fish
Bioaccumulation - Aquatic NonTarget
JE CHEMISTRY
Nature of Residue - Plants
Nature of Residue - Livestock
Residue Analytical Method - Plants
Residue Analytical Method - Animal
USE PATTERN CITATION(S)
A,C,E
A,C,E
A,C,E
A,C,E
A,C,E
A,C,E
A,C,E
A,C,E
A,C,E
A,C,E
A,C,E
A,C,E
A,C,E
A,C,E
A,C,E
A,C,E
A,C,E
A,C,E
A,C,E
A,C,E
inapplicable
inapplicable
40825801
40825802
40194201
waived
reserved
waived
reserved
inapplicable
waived
inapplicable
inapplicable
inapplicable
reserved
reserved
waived
41404201, 41774201, 41774202,
41362201, 00093415, 00093416,
00093422, 00115887, 00115895,
00115908, 00115932, 00116381,
00116748, 00116386, 41082501,
00062094, 00115216, 00115889
inapplicable
41404201, 41774201, 41774202,
41362201, 00093415, 00093416,
00093422, 00115887, 00115895,
00115908, 00115932, 00116381,
00116748, 00116386, 41082501,
00062094, 00115216, 00115889
63
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Data Supporting Guideline Requirements for the Reregistration of Fenthion
REQUIREMENT
USE PATTERN
CITATION(S)
171-4E Storage Stability
171-4F
171-4G
171-4H
171-41
171-4J
171-4K
171-4L
Magnitude of Residues - Potable H2O
Magnitude of Residues in Fish
Magnitude of Residues - Irrigated Crop
Magnitude of Residues - Food
Handling
Magnitude of Residues -
Meat/Milk/Poultry/Egg
Crop Field Trials
Processed Food
00093415, 00093416, 00093422,
00115887, 00115895, 00115908,
A,C,E 00115932, 00116381, 00116748,
00116386, 41082501, 00062094,
00115216,00115889
A,C,E waived
A,C,E reserved
A,C,E inapplicable
A,C,E inapplicable
A,C,E reserved
A,C,E
A,C,E
inapplicable
inapplicable
64
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Appendix C. Technical Support Documents
Additional documentation in support of this interim RED is maintained in the OPP docket, located in
Room 119, Crystal Mall #2, 1921 Jefferson Davis Highway, Arlington, VA. It is open Monday through
Friday, excluding legal holidays, from 8:30 am to 4:00 pm.
The docket initially contained preliminary risk assessments and related documents as of August 10,
1998. Sixty days later the first public comment period closed. The EPA then considered comments,
revised the risk assessment, and added the formal "Response to Comments" document and the revised risk
assessment to the docket on June 16, 1999.
All documents, in hard copy form, may be viewed in the OPP docket room or downloaded or
viewed via the Internet at the following site:
www. epa.gov/pesticides/op
These documents include:
HED Documents:
1. Health Effects Preliminary Assessment
• Summary
• Report of the Hazard Identification Assessment Review Committee
2. Revised Health Effects Assessment
• Overview of Fenthion Revised Risk Assessment
• Fenthion Summary
• Revised Assessment, February 18, 1999
• Revised Assessment, March 5, 1999
Occupational and Residential Exposure Assessment
Acute and Chronic Dietary Exposure Analysis
• Replacement of Human Study Used in Risk Assessments
• Re-evaluation of the Dermal Absorption Factor
Quantitative Usage Analysis
• Response to Comments on the Preliminary Risk Assessments
EFED Documents:
1. Environmental Fate and Effects Preliminary Assessment
• Environmental Fate and Effects Preliminary Assessment
2. Revised Environmental Fate and Effects Assessment
• Addendum to the Revised Environmental Fate and Effects Assessment
Bird kills from Adult Mosquito Sprays in Collier Co., Florida
65
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66
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Appendix D. Citations Considered to be Part of the Data Base Supporting the Interim
Reregistration Decision (Bibliography)
GUIDE TO APPENDIX D
1. CONTENTS OF BIBLIOGRAPHY. This bibliography contains citations of all studies considered
relevant by EPA in arriving at the positions and conclusions stated elsewhere in the Interim
Reregistration Eligibility Document. Primary sources for studies in this bibliography have been the
body of data submitted to EPA and its predecessor agencies in support of past regulatory decisions.
Selections from other sources including the published literature, in those instances where they have
been considered, are included.
2. UNITS OF ENTRY. The unit of entry in this bibliography is called a "study". In the case of
published materials, this corresponds closely to an article. In the case of unpublished materials
submitted to the Agency, the Agency has sought to identify documents at a level parallel to the
published article from within the typically larger volumes in which they were submitted. The resulting
"studies" generally have a distinct title (or at least a single subject), can stand alone for purposes of
review and can be described with a conventional bibliographic citation. The Agency has also
attempted to unite basic documents and commentaries upon them, treating them as a single study.
3. IDENTIFICATION OF ENTRIES. The entries in this bibliography are sorted numerically by
Master Record Identifier, or "MRID" number. This number is unique to the citation, and should be
used whenever a specific reference is required. It is not related to the six-digit "Accession Number"
which has been used to identify volumes of submitted studies (see paragraph 4(d)(4) below for
further explanation). In a few cases, entries added to the bibliography late in the review may be
preceded by a nine character temporary identifier. These entries are listed after all MRID entries.
This temporary identifying number is also to be used whenever specific reference is needed.
4. FORM OF ENTRY. In addition to the MRID, each entry consists of a citation containing standard
elements followed, in the case of material submitted to EPA, by a description of the earliest known
submission. Bibliographic conventions used reflect the standard of the American National Standards
Institute (ANSI), expanded to provide for certain special needs.
a Author. Whenever the author could confidently be identified, the Agency has chosen to
show a personal author. When no individual was identified, the Agency has shown an
identifiable laboratory or testing facility as the author. When no author or laboratory could
be identified, the Agency has shown the first submitter as the author.
b. Document date. The date of the study is taken directly from the document. When the date
is followed by a question mark, the bibliographer has deduced the date from the evidence
contained in the document. When the date appears as (1999), the Agency was unable to
determine or estimate the date of the document.
67
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c. Title. In some cases, it has been necessary for the Agency bibliographers to create or
enhance a document title. Any such editorial insertions are contained between square
brackets.
d. Trailing parentheses. For studies submitted to the Agency in the past, the trailing
parentheses include (in addition to any self-explanatory text) the following elements
describing the earliest known submission:
(1) Submission date. The date of the earliest known submission appears immediately
following the word "received."
(2) Administrative number. The next element immediately following the word "under" is
the registration number, experimental use permit number, petition number, or other
administrative number associated with the earliest known submission.
(3) Submitter. The third element is the submitter. When authorship is defaulted to the
submitter, this element is omitted.
(4) Volume Identification (Accession Numbers). The final element in the trailing
parentheses identifies the EPA accession number of the volume in which the original
submission of the study appears. The six-digit accession number follows the symbol
"CDL," which stands for "Company Data Library." This accession number is in turn
followed by an alphabetic suffix which shows the relative position of the study within
the volume.
68
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BIBLIOGRAPHY
MRID CITATION
00062094 Chemagro (1976) [Residues of Fenthion in Swine Tissue]: Report No. 36071. (Compilation; unpublished
study including report no. 48661, received Aug 2, 1977 under 11556-37; submitted by Bay vet, Shawnee
Mission, Kans.; CDL:230979-I)
00093415 Mobay Chemical Corporation (1966) Fenthion: Analytical, Residue, and Flavor Information on Backline
Application to Cattle. Includes method dated Aug 18, 1965. (Compilation; unpublished study, including
report nos. 16,509,16,913, 16,951..., received Jul 22, 1966 under 7F0531; CDL:090637-A; 090636; 090638)
00093416 Mobay Chemical Corporaiton (1966) Fenthion: Analytical, Residue, and Flavor Information on Backline
Application to Cattle: Supplement No. 1. (Compilation; unpublished study received Jul 22, 1966 under
7F0531;CDL:090637-B)
00093422 Mobay Chemical Corporation (1966) [Analytical, Residue and Flavor Information on Application of
Fenthion to Cattle]. (Compilation; unpublished study, including report nos. 17015,17062, 17362...,
received Jul 22, 1966 under 7F0531; CDL:090638-B)
00104232 Johnson, M.J.; Cavagnol, J.C. (1965) Analysis of Tiguvon 2 Ib/gal Spray Concentrate and 2% Pour-on:
Report No. 17279. (Unpublished study received Jul 22, 1966 under 7F0531; submitted by Mobay
Chemical Corp., Kansas City, Mo.; CDL:090639-D)
00115216 Bayvet (1973) [Analyses for Residues of Fenthion in Swine]. (Compilation; unpublished study received
Sep 14, 1982 under 11556-34; CDL:248407-A)
00115887 Mobay Chemical Corp. (1970) [Fenthion Residues in Milk, Eggs, Poultry Tissues and Alfalfa Hay].
(Compilation; unpublished study received on unknown date under 9F0811; CDL:093129-A)
00115889 Mobay Chemical Corp. (1973) Fenthion: Analytical and Residue Information on Backline Application to
Swine. (Compilation; unpublished study receivedFeb 19, 1974 under4F1472; CDL:093919-A)
00115895 Bayvet (1970) Fenthion: Analytical and Residue Information on Spotton Application to Cattle.
(Compilation; unpublished study received Mar 14, 1972; Jun20, 1972 under 11556-37; CDL:102518-A)
00115908 Bayvet (1974) [Fenthion Residue Determination in Various Products]. (Compilation; unpublished study
received Sep 3, 1975 under 11556-37; CDL:195118-A)
00115926 Brady, U.; Arthur, B. (1961) Metabolism of O,O-dimethyl O-[4-(methylthio)-M-tolyl] phosphorothioate
by white rats. Journal of Economic Entomology 54(6): 1232-1236. (Submitter 6782; also In unpublished
submission received Sep 13,1976 under unknown admin, no.; submitted by Mobay Chemical Corp.,
Kansas City, MO; CDL:225821-B)
00115932 Thornton, J. (1977) To Determine Possible Tissue Residues Resulting from Dermal Backline Application
ofLysoff: Report No. 54691. (Unpublished study received Aug 2, 1977 under 11556-48; submitted by
Bayvet, Shawnee Mission, KS; CDL:230980-A)
69
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BIBLIOGRAPHY
MRID CITATION
00116381 Mobay Chemical Corp. (1969) Fenthion: Analytical and Residue Information on Backline Application to
Cattle. (Compilation; unpublished study received Jul 9, 1969 under 3125-238; CDL:007184-A)
00116386 Chemagro (1972) [Fenthion: Residues in Cattle]: Report No. 33149. (Unpublished study received Jun 6,
1972 under 11556-34; submitted by Bayvet, Shawnee Mission, KS; CDL:014018-B)
00116396 Schaefer, C.; Dupras, E. (1970) The effects of water quality, temperature and light on the stability of
organophosphorus larvicides used for mosquito control. Pages 67-75, In Proceedings and Papers of the
Thirty-Seventh Annual Conference of the California Mosquito Control Assn., Inc; Jan 27-29, 1969.
[S.I.]: The Assoc. (Also In unpublished submission received Aug 3,1970 under 1F1019; submitted by
Mobay Chemical Corp., Kansas City, MO; CDL:091069-C)
00116748 Mobay Chemical Corp. (1967) [Study: Fenthion Residue in Selected Products]. (Compilation;
unpublished study received Jul 22,1966 under 7F0531; CDL:095237-I)
00132309 Mobay Chemical Corp. (1982) Baytex: Residue Chemistry on Fruits (Grapefruit, Oranges and Mangoes):
Brochure No. 1128; Document No. AS 83-2312. (Compilation; unpublished study received Oct 14, 1983
under 4E2983; CDL:072021-A)
00147245 Rosenblum, I. (1980) A Safety Evaluation of Fenthion (S1752) in Rhesus Monkeys (Macaca mulata):
Final Report: Report No. 68789. Unpublished study prepared by The Albany Medical College of Union
University. 117 p.
00147246 Coulston, F.; Griffin, T.; Rosenblum, I. (1979) Safety Evaluation of Fenthion in Human Volunteers: Final
Report: Report No. 68790. Unpublished study prepared by Albany Medical College, Institute of
Comparative and Human Toxicology. 106 p.
00154967 Mobay Chemical Corp. (1984) Residue and Metabolism Data: Baytex. Unpublished compilation. 553 p.
40085800 Mobay Corp. (1987) Submission of Product Chemistry Data to Support the Registration of Fenthion.
Compilation of 2 studies.
40085801 Talbott, T. (1987) Product Chemistry of Baytex Technical for Use Only in the Manufacture of Economic
Poisons: Baytex Liquid Concentrate Insecticide. Unpublished study prepared by Mobay Corp. 30 p.
40110401 Christopher, R.; Lane, J. (1987) Aqueous Photolysis of Baytex in Sterile Buffered Solution: Project ID:
BX-01-86. Unpublished study prepared by Mobay Corp. 27 p.
40186701 Stubblefield, W. (1987) Baytex (technical grade)-Acute LD50 to Bobwhite Quail: Report No. 94418:
Study No. 86-015-06. Unpublished study prepared by Mobay Corp. 27 p.
40186702 Stubblefield, W. (1987) Baytex Technical: Subacute Dietary LC50 to Bobwhite Quail: Report No. 94420:
Study No. 86-175-09. Unpublished study prepared by Mobay Corp. 29 p.
70
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BIBLIOGRAPHY
MRID CITATION
40186703 Stubblefield, W. (1987) Baytex Technical: Subacute Dietary LC50 to Mallard Ducks: ReportNo. 94424:
Study No. 86-175-08. Unpublished study prepared by Mobay Corp. 30 p.
40223001 Talbott, T. (1987) Product Chemistry of Baytex Technical for Use Only in the Manufacture of Economic
Poisons: Baytex Liquid Concentrate Insecticide: BR 1543. Unpublished compilation prepared by Mobay
Corp. 96 p.
40223002 Talbott, T. (1987) Product Chemistry of Baytex Technical for Use Only in the Manufacture of Economic
Poisons: Baytex Liquid Concentrate Insecticide: Supplement 1: BR 1542. Unpublished study prepared
by Mobay Corp. 12 p.
40246401 Forbis, A. (1987) Acute Flow-through Toxicity of Baytex to Daphnia magna: ABC Final Report #35598.
Unpublished Mobay Report 94576 prepared by Analytical Bio-Chemistry Laboratories, Inc. 179 p.
40274101 Swigert, J. (1987) Acute Flow-through Toxicity of Baytex to Bluegill Sunfish (Lepomis macrochirus):
Final Report #35597. Unpublished Mobay report 94632 prepared by Analytical Bio-Chemistry
Laboratories, Inc. 175 p.
40327001 Hayes, R. (1987) Chronic Feeding/Oncogenicity Study with Baytex in the Rat: Interim Report at Three
Months: Study No. 87-271-01. Unpublished study prepared by Mobay Corp. 5 p.
40329401 Kowalski, R.; Clemens, G.; Bare, J.; et al. (1987) A Teratology Study with Fenthion (Baytex Technical) in
the Rat: ReportNo. MDT0029: Toxicology ReportNo. 935. Unpublished Mobay ReportNo. 94815
prepared by Miles Laboratories. 192 p.
40341701 Hayes, R. (1987) Chronic Feeding Toxicity Study with Baytex in Dogs: Study No. 87-274-01.
Unpublished study prepared by Mobay Corp. 5 p.
40462701 Clemens, G.; Bare, J.; Hartnagel, R. (1987) A Teratology Study in the Rabbit with Fenthion (Baytex
Technical): Rept. No. MTD0039. Unpublished study prepared by Miles Inc. 143 p.
40495501 Surprenant, D. (1988) Acute Toxicity of Technical Grade Fenthion (Trade Name Baytex) to Sheepshead
Minnow (Cyprinodon variegatus) under Flow-through Conditions: Report #87-9-2506: Study
#274.0587.6152.505. Unpublished study prepared by Springbom Life Sciences, Inc. 31 p.
40564101 Surprenant, D. (1988) Acute Toxicity of Technical Grade Fenthion (...) to Eastern Oysters (Crassostera
virginica) Under Flow-through Conditions: Study No. 274-0587-6153-504. Unpublished study prepared
by Springborn Life Sciences, Inc. 35 p.
40564102 Surprenant, D. (1988) The Toxicity of Technical Grade Fenthion(...) to Rainbow Trout (Salmo gairdneri)
Embryo and Larvae: Study No. 274.0587.6154.121. Unpublished study prepared by Springbom Life
Sciences, Inc. 51 p.
71
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BIBLIOGRAPHY
MRID CITATION
40808601 Bailey, D. (1988) 21-Day Dermal Toxicity Study in Rabbits with Baytex Technical: HLA Study No.
339-118: Toxicology Report No. 1031. Unpublished study prepared by Hazleton Laboratories America,
Inc. 162 p.
40825801 Fritz, R.; Brauner, A.; Bomatsch, W. (1988) Degradation of Crop Protectants under Anaerobic
Conditions in the System Water/Sediment: Fenthion: Laboratory Project ID: 1520194-2. Unpublished
study prepared by Bayer Ag. 77 p.
40825802 Anderson, C.; Wilmes, R. (1988) Aerobic Aquatic Metabolism of Fenthion (Baytex): Laboratory Project
No.: M 151 0186-2. Unpublished study prepared by Bayer Ag. 53 p.
40856102 Tucker, J. (1985) Effects of Organophosphorous Mosquito Adulticides on Hatching Fish Larvae, Other
Estuarine Zooplankton, and Juvenile Fish: Baytex Objective No. 7110. Unpublished study. 103p.
40856105 Clark, J.; Borthwick, P.; Goodman, L.; et al. (1984) Effects of aerial thermal fog applications of fenthion on
caged pink shrimp, mysids and sheepshead minnows. Journal of the American Mosquito Control
Association 3(3): 466-472.
40856106 Clark, J.; Middaugh, D.; Hemmer, M.; et al. (1983) Effects of ground ulv applications of fenthion on
estuarine biota: i. study design and implementation. Journal of the Florida Anti-Mosquito Association
56(2): 51-62.
40856110 Tagatz, M.; Plaia, G. (1983) Effects of ground ulv applications of fenthion on estuarine biota: v.
responses of field and laboratory estuarine benthic communities. Journal of the Florida Anti-Mosquito
Association 56(2):76-81.
40871401 Forbis, A. (1988) Chronic Toxicity of [Carbon 14]-Baytex to Daphnia magna Under Flow-through Test
Conditions: ABC Final Report No. 35933. Unpublished Mobay report no. 98326 prepared by Analytical
Bio-Chemistry Laboratories, Inc. 36 p.
40879401 Surprenant, D. (1988) Acute Toxicity of Fenthion (...) to Mysid Shrimp (Mysidopsis bahia) Under
Flow-through Conditions: SLS Report 88-3-2680; SLS Study No. 274.0687.6151.515. Unpublished study
prepared by Springbom Life Sciences, Inc. 42 p.
40933601 Hayes, R.; Ramm, W. (1988) Subchronic Delayed Neurotoxicity Study of Fenthion Technical (Baytex)
with Hens: Study Nos. 86-418-01: 86-498-01. Unpublished study prepared by Mobay Corp. 186 p.
41026101 Waggoner, T. (1989) Product Chemistry of Cutter Blue Insecticide Cattle Ear Tag: Report Nos. 73852;
73854; 73855. Unpublished study prepared by Mobay Corp. 25 p.
41026102 Rose, W. (1989) Stability of Fenthion Plus Piperonyl Butoxide Ear Tags: Project ID: 86-303-141.
Unpublished study prepared by Mobay Corp. 8 p.
41026104 Davis, J. (1989) Validation of Test Method TMC-8.05 for Determining Fenthion Sulfoxide, Fenthion
S-Methyl and Piperonyl Butoxide in Fenthion Plus Piperonyl Butoxide Ear Tags by High Performance
72
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BIBLIOGRAPHY
MRID CITATION
Liquid Chromatography: Project ID: B460 P53-59, P81-100. Unpublished study prepared by Mobay
Corp. 30 p.
41026105 Rose, W. (1989) In vivo and in vitro Depletion and Weight Loss Studies of Fenthion Plus Piperonyl
Butoxide Ear Tags: Project ID: 86-404-51. Unpublished study prepared by Mobay Corp. 9 p.
41082501 Waggoner, T. (1989) Residue Chemistry of Cutter Blue Insecticide Cattle Ear Tag: Lab Report No. 73853.
Unpublished study prepared by Mobay Corp., Animal Health Division 23 p.
41103701 Sangha, G.; Ramm, W. (1989) Special Testing Ocular Effects Studies with Baytex (Fenthion): Acute Oral
Rat; Subchronic Oral Rat; Six-Month Oral Dog, Rabbit, or Monkey: Report No. AC 98583. Unpublished
study prepared by Mobay Corp. 67 p.
41283401 Flucke, W. (1988) E 1752 Technical: Study of the Effect on the Neurotoxic Esterase (NTE) Following Oral
Administration to Hens: Lab Project Numbers: 99275: T/3021893: 17307. Unpublished study prepared
by Bayer AG 38 p.
41283402 Flucke, W. (1988) E 1752 Technical: Study of the Effect on the Neurotoxic Esterase (NTE) Following
Dermal Application to Hens: Lab Project Number: 999646: 17308: T/3021893. Unpublished study
prepared by BayerAG 39 p.
41283403 Putman, D.; Morris, M. (1989) Chromosome Aberrations in Chinese Hamster Ovary (CHO) Cells: Final
Report: Lab Project Number: T8301/337 : 1144. Unpublished study prepared by Microbiological
Associates, Inc. 28 p.
41283404 Herbold,B. (1987) E 1752: Salmonella/Microsome Test for Point-Mutagenic Effect: Lab Project Number:
98366. Unpublished study prepared by BayerAG 42 p.
41348601 Kowalski, R.; Clemens, G.; Jasty, V. et al. (1989) A Two-generation Reproduction Study with Fenthion
(Baytex) in the Rat: Lab Project Nos. 99811; 1166; 8765. Unpublished study prepared by Miles, Inc.,
Toxicology Dept. 1046 p.
41632801 Christenson, W. (1990) Chronic Feeding Toxicity Study of Fenthion Technical (Baytex) with Dogs: Lab
Project Number: 87-274-01. Unpublished study prepared by Mobay Corporation. 406 p.
41743101 Christenson, W. (1990) Combined Chronic Toxicity/Oncogenicity Study of Technical Grade Fenthion
(Baytex) with Rats: Lab Project Number: 87-271-01: 100586. Unpublished study prepared by Mobay
Corp., Corporate Toxicology Dept. 2826 p.
41743101 Christenson, W. (1990) Combined Chronic Toxicity/Oncogenicity Study of Technical Grade Fenthion
(Baytex) with Rats: Lab Project Number: 87-271-01: 100586. Unpublished study prepared by Mobay
Corp., Corporate Toxicology Dept. 2826 p.
73
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BIBLIOGRAPHY
MRID CITATION
41869201 Leser, K.; Suberg, H. (1990) E 1752: Oncogenicity Study on B6C3FlMice (Feeding Study for Periods of
up to 24 Months): Lab Project Number: 100581: 19624. Unpublished study prepared by Bayer Ag. 2185
P-
42167901 Talbott, T. (1991) Product Chemistry of Baytex Technical for Use Only in the Manufacture of Economic
Poisons: Baytex Liquid Concentrate Insecticide: Lab Project Number: ANR-01591: MCL0117.
Unpublished study prepared by Mobay Corp. 37 p.
42167902 Talbott, T. (1991) Product Chemistry of Baytex Technical for Use Only in the Manufacture of Economic
Poisons: Baytex Liquid Concentrate Insecticide: Lab Project Number: 91885: 94377:100617. Unpublished
study prepared by Mobay Corp. 41 p.
42167903 Talbott, T. (1991) Product Chemistry of Baytex Technical for Use Only in the Manufacture of Economic
Poisons: Baytex Liquid Concentrate Insecticide: Lab Project Number: ANR-01591: MCL0120.
Unpublished study prepared by Mobay Corp. 40 p.
42457201 Christenson, W. (1992) Combined Chronic Toxicity/Oncogenicity Study of Technical Grade Fenthion
(Baytex) with Rats: A Supplement: Lab Project Number: 87-271-01: 100586-1. Unpublished study
prepared by Miles, Inc. 16 p.
42457201 Christenson, W. (1992) Combined Chronic Toxicity/Oncogenicity Study of Technical Grade Fenthion
(Baytex) with Rats: A Supplement: Lab Project Number: 87-271-01: 100586-1. Unpublished study
prepared by Miles, Inc. 16 p.
42699902 Christenson, W. (1993) Combined Chronic Toxicity/Oncogenicity Study of Fenthion Technical
(BAYTEX) with Rats: A Supplemental: Lab Project Number: 87-271-01: 100586-2. Unpublished study
prepared by Miles Inc. 2577 p.
42699902 Christenson, W. (1993) Combined Chronic Toxicity/Oncogenicity Study of Fenthion Technical
(BAYTEX) with Rats: A Supplemental: Lab Project Number: 87-271-01: 100586-2. Unpublished study
prepared by Miles Inc. 2577 p.
42759701 Leser, K.; Sunberg, H. (1993) E 1752: Oncogenicity Study on B6C3F1 Mice (Feeding Study for Periods of
up to 24 Months): A Supplemental: Lab Project Number: T 0020495: 19624: 100581-1. Unpublished study
prepared by Bayer AG, Dept. of Toxicology. 95 p.
42901401 Kowalski, R.; Clemens, G.; Jasty, V.; et al. (1993) A Two-Generation Reproduction Study with Fenthion
(BAYTEX) in the Rat: Supplemental Submission to EPA MRID No. 41348601: Lab Project Number: 99811.
Unpublished study prepared by Toxicology-Healthcare Miles Inc. 252 p.
42901402 Christenson, W. (1993) Chronic Feeding Toxicity Study of Fenthion (BAYTEX) with Dogs:
Supplemental Submission to EPA MRID No. 41632801: Lab Project Number: 87-274-01. Unpublished
study prepared by Miles Inc. 53 p.
74
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BIBLIOGRAPHY
MRID CITATION
42901403 Goethem, D.; Leser, K. (1993) Oncogenicity Study on B6C3F1 Mice (Feeding Study for Periods up to 24
Months): E 1752 (Fenthion): Supplemental Submission to EPA MRID No. 41869201: Lab Project Number:
T0020495. Unpublished study prepared by Bayer AG Department of Toxicology. 34 p.
44326401 Dreist, M.; Popp, A. (1997) E 1752 (Common Name: Fenthion):Acute Oral Neurotoxicity Screening Study
in Wistar Rats: Lab Project Number: 26113: T 1059124: 107649. Unpublished study prepared by Bayer
AG. 444 p. (Relates to L0000218)
75
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76
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Appendix E. Generic Data Call-In
See attached table for a list of generic data requirements. Note that a complete Data Call-in (DCI),
with all pertinent instructions, is being sent to registrants under separate cover.
77
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78
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Requirements Status and Registrant's Response PAGE 1 OF 1
79
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COMMENTS FOR GUIDELINE REQUIREMENTS PAGE 1 of 1
80
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Appendix F. Product Specific Data Call-In
See attached table for a list of product-specific data requirements. Note that a complete Data Call-
in (DCI), with all pertinent instructions, is being sent to registrants under separate cover.
81
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82
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PRODUCT SPECIFIC REQUIREMENTS STATUS AND REGISTRANT'S RESPONSE
PAGE 1 OF 3
83
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REQUIREMENTS STATUS AND REGISTRANT'S RESPONSE PAGE 2OF 3
84
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REQUIREMENTS STATUS AND REGISTRANT'S RESPONSE PAGE 3OF 3
85
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PRODUCT SPECIFIC FOOTNOTES AND KEY DEFINITIONS FOR GUIDELINE
REQUIREMENTS PAGE 1 OF 2
86
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PRODUCT SPECIFIC FOOTNOTES AND KEY DEFINITIONS FOR GUIDELINE
REQUIREMENTS PAGE 2OF 2
87
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88
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Appendix G. EPA's Batching of Fenthion Products for Meeting Acute Toxicity Data
Requirements for Reregistration
In an effort to reduce the time, resources and number of animals needed to fulfill the acute toxicity
data requirements for reregistration of products containing Fenthion as the primary active ingredient, the
Agency has batched products which can be considered similar for purposes of acute toxicity. Factors
considered in the sorting process include each product's active and inert ingredients (identity, percent
composition and biological activity), type of formulation (e.g., emulsifiable concentrate, aerosol, wettable
powder, granular, etc.), and labeling (e.g., signal word, use classification, precautionary labeling, etc.). Note
the Agency is not describing batched products as "substantially similar" since some products within a batch
may not be considered chemically similar or have identical use patterns.
Using available information, batching has been accomplished by the process described in the
preceding paragraph. Notwithstanding the batching process, the Agency reserves the right to require, at any
time, acute toxicity data for an individual product should need arise.
Registrants of products within a batch may choose to cooperatively generate, submit or cite a single
battery of six acute lexicological studies to represent all the products within that batch. It is the registrants'
option to participate in the process with all other registrants, only some of the other registrants, or only their
own products within in a batch, or to generate all the required acute lexicological studies for each of their
own products. If the registrant chooses to generate the data for a batch, he/she must use one of the
products within the batch as the test material. If the registrant chooses to rely upon previously submitted
acute toxicity data, he/she may do so provided that the database is complete and valid by today's standards
(see acceptance criteria attached), the formulation tested is considered by EPA to be similar for acute
toxicity, and the formulation has not been significantly altered since submission and acceptance of the acute
toxicity data. Regardless of whether new data is generated or existing data is referenced, the registrants
must clearly identify the test material by EPA Registration Number. If more than one confidential statement
of formula (CSF) exists for a product, the registrant must indicate the formulation actually tested by
identifying the corresponding CSF.
In deciding how to meet the product specific data requirements, registrants must follow the
directions given in the Data Call-in (DCI) Notice and its attachments appended to the RED. The DCI
Notice contains two response forms which are to be completed and submitted to the Agency within 90 days
of receipt. The first form, "Data Call-in Response, " asks whether the registrant will meet the data
requirements for each product. The second form, "Requirements Status and Registrant's Response," lists
the product specific data required for each product, including the standard six acute toxicity tests. A
registrant who wishes to participate in a batch must decide whether he/she will provide the data or depend
on someone else to do so. If the registrant supplies the data to support a batch of products, he/she must
select the one of the following options: Developing Data (Option 1), Submitting an Existing Study (Option
4), Upgrading an Existing Study (Option 5), or Citing an Existing Study (Option 6 ). If a registrant depends
on another's data, he/she must choose among: Cost sharing (Option 2), Offers to Cost Share (Option 3) or
Citing an Existing Study (Option 6). If a registrant does not want to participate in a batch, the choices are
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Options 1, 4, 5 or 6. However, a registrant should know that choosing not to participate in a batch does not
preclude other registrants in the batch from citing his/her studies and offering to cost share (Option 3) those
studies.
Ten products were found which contain Fenthion as the active ingredient. These products have
been placed into two batches and a "No Batch" category in accordance with the active and inert
ingredients and type of formulation.
Batch 1
EPA Reg. No.
3125-148
3125-197
11556-36
Percent active ingredient
95.0
95.0
95.0
Formulation Type
Liquid
Liquid
Liquid
Batch 2
EPA Reg. No.
5481-83
5481-84
5481-101
Percent active ingredient
1.0
1.0
2.0
Formulation Type
Solid
Solid
Solid
No Batch
EPA Reg. No.
11556-34
11556-37
11556-48
11556-105
Percent active ingredient(s)
3.0
20.0
7.6
Fenthion-20%
Piperonyl Butoxide-15%
Formulation Type
Liquid
Liquid
Liquid
Solid
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Appendix H. List of Registrants Sent This Data Call-In
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Insert List-Page 1 of 1
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Appendix I. List of Available Related Documents and Electronically Available Forms
Pesticide Registration Forms are available at the following EPA internet site:
http://www.epa.gov/opprd001/fortns/
Pesticide Registration Forms (These forms are in PDF format and require the Acrobat reader)
Instructions
1. Print out and complete the forms. (Note: Form numbers that are bolded can be filled out on
your computer then printed.)
2. The completed form(s) should be submitted in hardcopy in accord with the existing policy.
3. Mail the forms, along with any additional documents necessary to comply with EPA regulations
covering your request, to the address below for the Document Processing Desk.
DO NOT fax or e-mail any form containing 'Confidential Business Information' or 'Sensitive
Information.'
If you have any problems accessing these forms, please contact Nicole Williams at (703)
308-5551 or by e-mail atwilliams.nicole@epamail.epa.gov.
The following Agency Pesticide Registration Forms are currently available via the internet at the following
locations:
8570-1
8570-4
8570-5
8570-17
8570-25
8570-27
8570-28
8570-30
8570-32
8570-34
8570-35
8570-36
8570-37
Application for Pesticide Registration/Amendment
Confidential Statement of Formula
Notice of Supplemental Registration of Distribution of a Registered
Pesticide Product
Application for an Experimental Use Permit
Application for/Notification of State Registration of a Pesticide To
Meet a Special Local Need
Formulator's Exemption Statement
Certification of Compliance with Data Gap Procedures
Pesticide Registration Maintenance Fee Filing
Certification of Attempt to Enter into an Agreement with other
Registrants for Development of Data
Certification with Respect to Citations of Data (in PR Notice 98-5)
Data Matrix (in PR Notice 98-5)
Summary of the Physical/Chemical Properties (in PR Notice 98-1)
Self-Certification Statement for the Physical/Chemical Properties (in
PR Notice 98-1)
tittD://www.eDa.aov/ODDrd001/forms/8570-l.Ddf
tittp://www.epa.gov/opprd001/forms/8570-4.pdf
tittp://www.epa. gov/opprdOO l/forms/8570-5 .pdf
tittD://www.eDa. aov/ODDrdOO l/forms/8570- 1 7.Ddf
tittp://www.epa. aov/opprdOO l/forms/8570-25 .pdf
tittp://www.epa.gov/opprd001/forms/8570-27.pdf
tittp://www.epa.gov/opprd001/forms/8570-28.pdf
tittp://www.epa.aov/opprd001/forms/8570-30.pdf
tittp://www.epa.gov/opprd001/forms/8570-32.pdf
tittp://www.epa.gov/opppmsdl/PR Notices7pr98-5.pdf
tittp://www.epa.gov/opppmsdl/PR Notices7pr98-5.pdf
tittp://www.epa.gov/opppmsdl/PR Notices/pr98-l .pdf
tittp://www.epa.gov/opppmsdl/PR Notices/pr98-l .pdf
Pesticide Registration Kit
www.epa.gov/pesticides/registrationkit/
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Dear Registrant:
For your convenience, we have assembled an online registration kit which contains the following
pertinent forms and information needed to register a pesticide product with the U.S. Environmental
Protection Agency's Office of Pesticide Programs (OPP):
1. The Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA) and the Federal Food,
Drug and Cosmetic Act (FFDCA) as Amended by the Food Quality Protection Act
(FQPA)of 1996.
2. Pesticide Registration (PR) Notices
a. 83-3 Label Improvement Program-Storage and Disposal Statements
b. 84-1 Clarification of Label Improvement Program
c. 86-5 Standard Format for Data Submitted under FIFRA
d. 87-1 Label Improvement Program for Pesticides Applied through Irrigation Systems
(Chemigation)
e. 87-6 Inert Ingredients in Pesticide Products Policy Statement
f 90-1 Inert Ingredients in Pesticide Products; Revised Policy Statement
g. 95-2 Notifications, Non-notifications, and Minor Formulation Amendments
h. 98-1 Self Certification of Product Chemistry Data with Attachments (This
document is in PDF format and requires the Acrobat reader.)
Other PR Notices can be found at http://www.epa.gov/opppmsdl/PR_Notices
3. Pesticide Product Registration Application Forms (These forms are in PDF format and will
require the Acrobat reader.)
a. EPA Form No. 8570-1, Application for Pesticide Registration/Amendment
b. EPA Form No. 8570-4, Confidential Statement of Formula
c. EPA Form No. 8570-27, Formulator's Exemption Statement
d. EPA Form No. 8570-34, Certification with Respect to Citations of Data
e. EPA Form No. 8570-35, Data Matrix
4. General Pesticide Information (Some of these forms are in PDF format and will require the
Acrobat reader.)
a. Registration Division Personnel Contact List
b. Biopesticides and Pollution Prevention Division (BPPD) Contacts
c. Antimicrobials Division Organizational Structure/Contact List
d. 53 F.R. 15952, Pesticide Registration Procedures; Pesticide Data Requirements
(PDF format)
e. 40 CFR Part 156, Labeling Requirements for Pesticides and Devices (PDF format)
f. 40 CFR Part 158, Data Requirements for Registration (PDF format)
g. 50 F.R. 48833, Disclosure of Reviews of Pesticide Data (November 27, 1985)
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Before submitting your application for registration, you may wish to consult some additional sources
of information. These include:
1. The Office of Pesticide Programs' Web Site
2. The booklet "General Information on Applying for Registration of Pesticides in the United
States", PB92-221811, available through the National Technical Information Service
(NTIS) at the following address:
National Technical Information Service (NTIS)
5285 Port Royal Road
Springfield, VA 22161
The telephone number for NTIS is (703) 605-6000. Please note that EPA is currently in the
process of updating this booklet to reflect the changes in the registration program resulting
from the passage of the FQPA and the reorganization of the Office of Pesticide Programs.
We anticipate that this publication will become available during the Fall of 1998.
3. The National Pesticide Information Retrieval System (NPIRS) of Purdue University's Center
for Environmental and Regulatory Information Systems. This service does charge a fee for
subscriptions and custom searches. You can contact NPIRS by telephone at (765)
494-6614 or through their Web site.
4. The National Pesticide Telecommunications Network (NPTN) can provide information on
active ingredients, uses, toxicology, and chemistry of pesticides. You can contact NPTN by
telephone at (800) 858-7378 or through their Web site: ace.orst.edu/info/nptn.
The Agency will return a notice of receipt of an application for registration or amended
registration, experimental use permit, or amendment to a petition if the applicant or petitioner
encloses with his submission a stamped, self-addressed postcard. The postcard must contain
the following entries to be completed by OPP:
Date of receipt
EPA identifying number
Product Manager assignment
Other identifying information may be included by the applicant to link the acknowledgment
of receipt to the specific application submitted. EPA will stamp the date of receipt and
provide the EPA identifying File Symbol or petition number for the new submission. The
identifying number should be used whenever you contact the Agency concerning an
application for registration, experimental use permit, or tolerance petition.
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To assist us in ensuring that all data you have submitted for the chemical are properly coded
and assigned to your company, please include a list of all synonyms, common and trade
names, company experimental codes, and other names which identify the chemical (including
"blind" codes used when a sample was submitted for testing by commercial or academic
facilities). Please provide a CAS number if one has been assigned.
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