United States Prevention, Pesticides EPA 738-R-06-030
Environmental Protection and Toxic Substances July 2006
Agency (7508P)
Reregistration
Eligibility Decision
(RED) for Malathion
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REREGISTRATION ELIGIBILITY
DECISION
for
Malathion
Case No. 0248
Approved by:
Debra Edwards, Ph.D.
Director, Special Review and
Reregistration Division
Date
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TABLE OF CONTENTS
TABLE OF CONTENTS i
Malathion Reregistration Eligibility Decision Team iii
Glossary of Terms and Abbreviations iv
Abstract 1
I. Introduction 2
II. Chemical Overview 3
A. Regulatory History 3
B. Chemical Identification 3
C. Use Profile 5
III. Summary of Malathion Risk Assessment 7
A. Human Health Risk Assessment 7
1. Toxicity Summary 8
a. Acute Toxicity Profile 9
b. FQPA Safety Factor Considerations 9
c. Dose-Response and Benchmark Dose Analysis 10
d. Toxicological Endpoints 11
e. Toxicity Adjustment Factor for Malaoxon 14
f. Carcinogenicity 15
2. Endocrine Disruption 15
3. Dietary Exposure from Malathion and Malaoxon in Food 16
a. Population Adjusted Dose 16
b. Acute and Chronic Dietary (Food) Risk 17
c. Drinking Water Exposure 18
4. Residential Exposure and Risk 22
a. Residential Handler Risks 23
b. Residential Post-Application Risks 24
5. Aggregate Risk Assessment for Malathion 31
a. Acute Aggregate Risk 31
b. Chronic Aggregate Risk 34
c. Short-Term Aggregate Risk 34
d. Malathion Pesticide and Pharmaceutical Use Co-Exposure Assessment 36
6. Occupational Exposure and Risk 37
a. Occupational Handler Exposure and Risk 38
b. Occupational Post-Application Exposure and Risk 41
c. Incident Reports 44
B. Environmental Fate and Effects Assessment 46
1. Environmental Fate and Transport 46
2. Ecological Exposure and Risk 47
a. Terrestrial Organisms 48
b. Aquatic Organisms 51
c. Spray Drift 54
d. Wide Area Treatments with Malathion 55
e. Down-the-Drain Assessment 56
f. Endangered Species 57
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3. Ecological Incidents 58
IV. Risk Management, Reregistration, and Tolerance Reassessment 59
A. Determination of Reregistration Eligibility 59
B. Public Comments and Responses 59
C. Regulatory Position 60
1. Food Quality Protection Act Findings 60
a. "Risk Cup" Determination 60
b. Determination of Safety to U.S. Population 60
c. Determination of Safety to Infants and Children 60
2. Endocrine Disrupter Effects 61
3. Cumulative Risks 62
4. Endangered Species 62
D. Tolerance Reassessment Summary 63
E. Regulatory Rationale 75
1. Human Health Risk Management 75
a. Acute and Chronic Dietary (Food Only) Mitigation 75
b. Residential Risk Mitigation 75
c. Acute Aggregate Risk Mitigation 77
d. Chronic Aggregate Risk Mitigation 82
e. Short-Term Aggregate Risk Mitigation 82
f. Occupational Risk Mitigation 83
2. Non-Target Organism (Ecological) Risk Management 87
a. Terrestrial Organisms 87
b. Aquatic Organisms 87
3. Benefits of Malathion to Users 93
4. Isomalathion 94
5. Summary of Mitigation Measures 95
F. Other Labeling Requirements 97
1. Endangered Species Considerations 97
2. Spray Drift Management 98
V. What Registrants Need to Do 99
A. Manufacturing-Use Products 99
1. Generic Data Requirements 99
2. Labeling for Manufacturing-Use Products 99
B. End-Use Products 100
1. Additional Product-Specific Data Requirements 100
2. Labeling for End-Use Products 100
C. Labeling Changes Summary Table 1001
Appendix A 127
Appendix B 138
Appendix C 150
Appendix D 152
11
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Malathion Reregistration Eligibility Decision Team
Office of Pesticide Programs
Biological and Economic Analysis Assessment
Donald Atwood
Jin Kim
Timothy Kiely
Environmental Fate and Effects Risk Assessment
Norman Birchfield
Health Effects Risk Assessment
Jack Arthur
Anna Lowit
Sheila Piper
Louis Scarano
Registration Support
Marilyn Mautz
Risk Management
Tom Moriarty
Neil Anderson
General Counsel
Scott Garrison
in
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Glossary of Terms and Abbreviations
ai Active Ingredient
aPAD Acute Population Adjusted Dose
APHIS Animal and Plant Health Inspection Service
ARTF Agricultural Re-entry Task Force
BCF Bioconcentration Factor
CDC Centers for Disease Control
CDPR California Department of Pesticide Regulation
CFR Code of Federal Regulations
ChEI Cholinesterase Inhibition
cPAD Chronic Population Adjusted Dose
CSFII USDA Continuing Surveys for Food Intake by Individuals
CWS Community Water System
DCI Data Call-in
DEEM Dietary Exposure Evaluation Model
DL Double layer clothing {i.e., coveralls over SL}
EC Emulsifiable Concentrate Formulation
EDSP Endocrine Disrupter Screening Program
EDSTAC Endocrine Disrupter Screening and Testing Advisory Committee
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
EXAMS Tier II Surface Water Computer Model
FDA Food and Drug Administration
FFDCA Federal Food, Drug, and Cosmetic Act
FIFRA Federal Insecticide, Fungicide, and Rodenticide Act
FOB Functional Observation Battery
FQPA Food Quality Protection Act
FR Federal Register
IDFS Incident Data System
IPM Integrated Pest Management
RED Reregistration Eligibility Decision
LADD Lifetime Average Daily Dose
LC50 Median Lethal Concentration. Statistically derived concentration of a substance expected to cause
death in 50% of test animals, 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. Statistically derived single dose causing death in 50% of the test animals when
administered by the route indicated (oral, dermal, inhalation), expressed as a weight of substance per
unit weight of animal, e.g., mg/kg.
LOAEC Lowest Observed Adverse Effect Concentration
LOAEL Lowest Observed Adverse Effect Level
LOG Level of Concern
LOEC Lowest Observed Effect Concentration
mg/kg/day Milligram Per Kilogram Per Day
MOE Margin of Exposure
MP Manufacturing-Use Product
MRID Master Record Identification (number). EPA's system of recording and tracking studies submitted.
MRL Maximum Residue Level
N/A Not Applicable
NASS National Agricultural Statistical Service
NAWQA USGS National Water Quality Assessment
NMFS National Marine Fisheries Service
NOAEC No Observed Adverse Effect Concentration
IV
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NOAEL No Observed Adverse Effect Level
NPIC National Pesticide Information Center
NR No respirator
OP Organophosphorus
OPP EPA Office of Pesticide Programs
ORETF Outdoor Residential Exposure Task Force
PAD Population Adjusted Dose
PCA Percent Cropped Area
PDCI Product Specific Data Call-In
POP USDA Pesticide Data Program
PF10 Protections factor 10 respirator
PF5 Protection factor 5 respirator
PHED Pesticide Handler's Exposure Data
PHI Preharvest Interval
ppb Parts Per Billion
PPE Personal Protective Equipment
PRZM Pesticide Root Zone Model
RBC Red Blood Cell
RED Reregistration Eligibility Decision
REI Restricted Entry Interval
RfD Reference Dose
RPA Reasonable and Prudent Alternatives
RQ Risk Quotient
RTU (Ready-to-use)
RUP Restricted Use Pesticide
SCI-GROW Tier I Ground Water Computer Model
SF Safety Factor
SL Single layer clothing
SLN Special Local Need (Registrations Under Section 24(c) of FIFRA)
TEP Typical End-Use Product
TGAI Technical Grade Active Ingredient
TTRS Transferable Turf Residues
UF Uncertainty Factor
USDA United States Department of Agriculture
USFWS United States Fish and Wildlife Service
USGS United States Geological Survey
WPS Worker Protection Standard
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Abstract
The Environmental Protection Agency (EPA or the Agency) has completed the human
health and environmental risk assessments for malathion and is issuing its risk management
decision and tolerance reassessment. The risk assessments, which are summarized below, are based
on the review of the required target database supporting the use patterns of currently registered
products and additional information received through the public docket. After considering the risks
identified in the revised risk assessments, comments received, and mitigation suggestions from
interested parties, the Agency developed its risk management decision for uses of malathion that
pose risks of concern. As a result of this review, EPA has determined that malathion-containing
products are eligible for reregi strati on, provided that risk mitigation measures are adopted and
labels are amended accordingly. That decision is discussed fully in this document.
Malathion is a broad-spectrum organophosphate (OP) insecticide first registered in 1956. It
is used widely in agriculture for various food and feed crops, homeowner outdoor uses, ornamental
nursery stock, building perimeters, pastures and rangeland, and regional pest eradication programs.
Previous risk assessments indicated some drinking water, occupational handler and post-
application, residential bystander, and ecological risks of concern. Drinking water and residential
bystander risk estimates were revised based on refinements to the assessments and/or mitigation
measures, such as reduced maximum application rates and number of application permitted per year
for many use sites. Occupational risks have been mitigated through personal protective equipment
or engineering control requirements on the labels and extending re-entry intervals for some sites,
and ecological risks have been addressed through adding buffer zone and spray drift requirements to
the labels, and amending use patterns for many uses.
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I. Introduction
The Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA) was amended in 1988 to
accelerate the reregi strati on 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
reregi strati on 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"). Reregi strati on 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 or not the pesticide meets the "no unreasonable adverse effects" criteria of
FIFRA.
On August 3, 1996, the Food Quality Protection Act (FQPA) was signed into law. This Act
amends FIFRA and the Federal Food, Drug, and Cosmetic Act (FFDCA) to require reassessment of
all existing tolerances for pesticides in food. FQPA also requires EPA to review all tolerances in
effect on August 2, 1996, by August 3, 2006. In reassessing these tolerances, the Agency must
consider, among other things, aggregate risks from non-occupational sources of pesticide exposure,
whether there is increased susceptibility of infants and children, and the cumulative effects of
pesticides with a common mechanism of toxicity. Malathion belongs to a group of pesticides called
organophosphates (OPs), which share a common mechanism of toxicity by affecting the nervous
system via cholinesterase inhibition. When the Agency concludes that there is a reasonable
certainty of no harm from aggregate exposure, and the cumulative risks for pesticides which share a
common mechanism of toxicity, such as the OPs, are below the Agency's level of concern, the
tolerances are considered reassessed. EPA decided that, for those chemicals that have tolerances
and are undergoing reregi strati on, tolerance reassessment will be accomplished through the
reregi strati on process.
As mentioned above, FQPA requires EPA to consider available information concerning the
cumulative effects of a particular pesticide's residues and "other substances that have a common
mechanism of toxicity." Potential cumulative effects of chemicals with a common mechanism of
toxicity are considered because low-level exposures to multiple chemicals causing a common toxic
effect by a common mechanism could lead to the same adverse health effect as would a higher level
of exposure to any one of these individual chemicals. Malathion is a member of the OP class of
pesticides, which share a common mechanism of toxicity by affecting the nervous system via
cholinesterase inhibition. A cumulative risk assessment, which evaluates exposures based on a
common mechanism of toxicity, was conducted to evaluate the risk from food, drinking water,
residential, and other non-occupational exposures resulting from registered uses of OP pesticides,
including malathion. EPA has concluded that the cumulative risks associated with OP pesticides
are below the Agency's level of concern. For additional information, refer to the OP Cumulative
Assessment (2006 Update), which is available in EPA docket EPA-HQ-OPP-2006-0618 and on
EPA' s website at htt|x/ywwjvj;]^
This document presents EPA's revised human health and ecological risk assessments, its
tolerance reassessment, and reregi strati on eligibility decision (RED) for malathion. The document
consists of six sections. Section I contains the regulatory framework for reregi strati on/tolerance
reassessment; Section II provides an overview of the chemical and a profile of its use and usage;
Section III gives an overview of the human health and environmental effects risk assessments;
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Section IV presents the Agency's decision on reregi strati on eligibility and risk management; and
Section V summarizes the label changes necessary to implement the risk mitigation measures
outlined in Section IV. Finally, the Appendices list related information, supporting documents, and
studies evaluated for the reregi strati on decision. The revised risk assessments for malathion and all
other supporting documents are available in the Office of Pesticide Programs (OPP) public docket
(http://www.regulations.gov.) under docket number EPA-HQ-OPP-2004-0348.
II. Chemical Overview
A. Regulatory History
Malathion is a broad spectrum organophosphate insecticide and miticide first registered in
1956. Malathion has numerous commercial agricultural, industrial, governmental, and homeowner
uses. In 2000, approximately 11-13 million pounds of malathion were used annually; currently,
approximately 15 million pounds are used annually.
In February 1988, the Guidance for the Reregi strati on of Pesticide Products Containing
Malathion {Malathion Registration Standard) was issued. The Registration Standard summarized
the human health and ecological risk findings based on the data available at that time, and required
other studies to complete the malathion data base. The Registration Standard also imposed label
restrictions to reduce exposure resulting from indoor applications of malathion, and updated
environmental hazard statements on malathion product labels. Numerous data requirements needed
to complete the Agency's reassessment of malathion were imposed through Data Call-In (DCI)
Notices issued as part of the reregi strati on process of malathion. DCIs on malathion were issued in
1992, 1993, 1994, 1995, 1999, and 2004.
In February 2000, EPA issued its Preliminary Risk Assessment for the Reregistration
Eligibility Decision Document. The Preliminary Risk Assessment reflected the conclusion of the
OPP Hazard Identification Assessment Review Committee (HIARC), and the FQPA Safety Factor
Committee, as well as the OPP Cancer Assessment Review Committee. A preliminary ecological
risk assessment was also issued at that time. In September 2000, EPA issued a Revised Malathion
Risk Assessment. The revised assessment reflected comments received during the public comment
period, and incorporated new data the Agency received regarding exposure to agricultural workers.
The 2000 Revised Malathion Risk Assessment also included a revised cancer classification of
malathion. The 2000 Revised Ecological Risk Assessment changed little from the Preliminary
Ecological Risk Assessment.
In 1999, EPA required a developmental neurotoxicity study along with a comparative
cholinesterase study. These data were submitted to the Agency in 2002, and were assessed as part
of the Agency's revised risk assessment, which was issued for public comment in September 2005.
The 2005 Revised Human Health Risk Assessment also contained other changes, including a toxicity
adjustment factor for the primary metabolite malaoxon, and addressed the pharmaceutical use of
malathion. As no new data were received with respect to ecological fate or hazard of malathion, the
ecological risk assessment remained unchanged between 2000 and 2005.
B. Chemical Identification
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Malathion is a colorless to amber liquid with a mercaptan odor and boiling point of 156-
157°C. Malathion is soluble in water and is readily soluble in most alcohols, esters, aromatic
solvents, and ketones, and is only slightly soluble in aliphatic hydrocarbons. Below is a summary
of the chemical compound malathion.
Malathion Test Compound Nomenclature
Chemical Structure
Empirical Formula
Common name
IUPAC name
CAS Registry Number
Chemical Class
Known Impurities of Concern
CK , OC,H,
" I
p 1
HXO'"/ ^S ^1
OCH3 1
O '~~ OC2H5
CloHi9OsPS2
Malathion
O,O-dimethyl dithiophosphate of diethyl mercaptosuccinate
121-75-5
Organophosphate
Empirical Formula: C10H19O6PS2
Common Name: Isomalathion
IUPAC Name: Butanedioic acid,
[[methoxy(methylthio)phosphinyl]thio]-, diethylester
CAS Registry Number: 3344-12-5
Malaoxon is the primary metabolite of malathion and, under certain conditions, is formed as
an environmental breakdown product of malathion making it available for direct human exposure.
Below is a summary of the chemical compound malaoxon.
Malaoxon Test Compound Nomenclature
Chemical Structure
Empirical Formula
Common name
IUPAC name
CAS Registry Number
Chemical Class
(X OC2H5
o ^V^
/p\ ^\
H,CO / S >
OCH3 1
O "OC2HS
CloHigOvPS
Malaoxon (the active ChE inhibiting
metabolite of malathion)
O,O-dimethyl thiophosphate of diethyl mercaptosuccinate
1634-78-2
Organophosphate
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A number of impurities have been reported to be present in representative technical
formulations of malathion. Isomalathion is an impurity known to be present at very low levels in
both technical grade and end-use product samples of malathion. These low levels of isomalathion
may be formed during the manufacturing process of malathion, and low levels of isomalathion may
also be formed if malathion undergoes chemical rearrangement (isomerization) during product
storage. Data provided by the registrant indicate that Fyfanon® Technical (EPA Reg. No. 4787-5)
is stable for up to 1 year when stored under warehouse conditions (20-23°C), although a small
amount of isomalathion accumulated (increase from <0.01% to about 0.1%). Storage of malathion
at 54°C for 2 weeks resulted in an increase of isomalathion from about 0.05% to 0.2%.
C. Use Profile
Malathion is a broad-spectrum organophosphorous (OP) insecticide, used widely in
agriculture and regional pest eradication programs. The following use sites and crops are being
supported and were included in this risk assessment. A detailed table of the uses of malathion
eligible for reregi strati on is available in Appendix A.
Food and Feed Crops - Alfalfa; apricot; asparagus; avocado; barley; bean (succulent and dry); beets
(table); birdsfoot trefoil; blackberry; blueberry; boysenberry; broccoli; broccoli raab; Brussels
sprout; cabbage (including Chinese); carrot; cauliflower; celery; chayote; cherry; chestnut; clover;
collards; corn (field; sweet; and pop); cotton; cucumber; currant; dandelion; date; dewberry;
eggplant; endive; escarole; potato; fig; garlic; gooseberry; grape; grapefruit; guava; hay grass; hops;
horseradish; kale; kohlrabi; kumquat; leek; lemon; lespedeza; lettuce (head and leaf); lime;
loganberry; lupine; macadamia nut; mango; melon; mint; mushroom; mustard greens; nectarines;
oats; okra; onion; orange; papaya; parsley; parsnip; passion fruit; pea; peach; pear; pecan; pepper;
pineapple; pumpkin; radish; raspberry; rice; rutabaga; rye; salsify; shallot; sorghum; spinach; spring
wheat; squash; strawberry; sweet potato; Swiss chard; tangelo; tangerine; tomato (including
tomatillo); turnip; vetch; walnut; watercress; watermelon; wheat (spring, and winter); wild rice; and
yam; indoor stored commodity treatment and empty storage facilities for barley, corn, oats, rye, and
wheat.
Other Uses - Homeowner outdoor uses: ornamental flowering plants, ornamental lawns, ornamental
turf, vegetable gardens and fruit trees; ornamental flowers, shrubs, and trees; Christmas tree
plantations; slash pine; ornamental nursery stock; woody plants; building perimeters (domestic
dwellings as well as commercial structures); uncultivated nonagricultural areas; outdoor garbage
dumps; intermittently flooded areas; irrigation systems; pastures; and rangeland.
Regional Pest Eradication Programs - Boll Weevil eradication (USDA sponsored program), Medfly
control (USDA), and mosquito control (public health).
Pharmaceutical Malathion - There is a pharmaceutical use of malathion as a pediculicide for the
treatment of head lice and their ova, which is regulated by the Food and Drug Administration
(FDA).
Types/Formulations Registered - Malathion is formulated as an emulsifiable concentrate (EC), dust
(D), wettable powder (WP), ready-to-use (RTU) liquid, and as a pressurized liquid (PrL). The EC
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and RTU formulations may contain up to 82% and 96.8% active ingredient (ai), respectively.
Several of the 96.8% ai RTU liquids are intended for ultra-low-volume (ULV) application with the
use of aerial or ground equipment. Malathion is typically applied as multiple foliar treatments as
needed to control various pest species.
Application Equipment - Aircraft (fixed wing, and rotary), duster, fogger, ground boom, irrigation,
shaker can, sprayer, and spreader.
Target Pests - Ants, aphids, apple mealybug, armyworm, bagworm, beetle, borer, casebearer,
blackheaded fireworm, blueberry maggot, cadelle, caterpillars, cattle lice, cherry fruitworm,
cockroaches, corn earworm, corn rootworms, cotton fleahopper, cotton leaf perforator, cotton
leafworm, cranberry fruitworm, crickets, currant cutworm, earwigs, European fruit lecanium, fall
cankerworm, fleahoppers, fleas, flies, fruit flies, fungus gnats, garden webworm, grain borer, grape
phylloxera, grasshoppers, green cloverworm, greenbug, groundpearls, hornets, imported
cabbageworm, imported currantworm, ked, leafhoppers, leafrollers, leafminer, looper, millipedes,
mites, mosquitoes (adult, larvae), moths, kermes, mushroom flies, omnivorous leaftier, onion
maggot, orange tortrix, orangeworms, pear psylla, pecan phylloxera, pepper maggot, pickleworm,
pillbugs, pine needle sheathminer, plant bugs, plum curculio, poultry lice, rose chafer, sawflies,
scales, scorpions, silverfish, sorghum midge, sowbugs, spiders, spittlebugs, springtails, strawberry
leafroller, sugarbeet root maggot, tadpole shrimp, thrips, ticks, tingids, tomato fruitworm, vetch
bruchid, wasps, weevil, whiteflies, and wild rice worm.
Application Rate Ranges
General Agriculture: 0.175 - 6.25 Ib ai/A
Home and Garden: 0.000085 - 0.0003 Ib ai/ft2
Boll Weevil Eradication Program: 0.3-1.22 Ib ai/A
Fruit Fly Treatment: 0.09 - 0.18 Ib ai/A
Public Health Adulticide: 0.11- 0.23 Ib ai/A
Typical Usage - An average annual estimate of total domestic usage of malathion is approximately
15 million pounds of malathion as active ingredient (ai). Approximately 10.2 million pounds ai are
applied through the USD A Boll Weevil Eradication Program, 1.5 million pounds are applied to
agricultural crops, and 300,000 pounds are applied as postharvest grain treatment to corn, wheat,
and oats. Approximately 500,000 pounds ai are used on non-agricultural sites, such as around
buildings, roads, and ditches. Approximately 1.5 million pounds are applied in quarantine programs
and public health (adulticide) programs, and 1 million pounds are used in the residential/home
owner market.
Percent crop treated - For the majority of the agricultural sites for which malathion is registered and
the Agency has use data, less than 1% of the crop is typically treated with malathion; however on
several agricultural crops, malathion is applied to 10% of the crop or more.
Percent Crop
Treated Range Crops
>10 blueberries, raspberries, strawberries, limes, cotton, cherries, garlic, greens,
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dates, celery.
5-10 okra, walnuts, lettuce, avocados, onions, carrots, squash, asparagus,
cantaloupes, cabbage, collards, kale.
1-5 alfalfa, pecans, wheat, rice, oranges, almonds, corn, peaches, apples, pears,
tomatoes, potatoes, sorghum, grapes, beets, lemons, broccoli,
cucumbers, grapefruit, pumpkins, sunflowers, watermelons, peas, corn,
beans, peppers, plums, prunes, spinach, apricots, cauliflower.
<1 Approximately 54 crops make up this category, but are not listed here.
III. Summary of Malathion Risk Assessment
The following is a summary of EPA's revised human health and ecological risk assessments for
malathion, as presented fully in the documents Malathion: Revised Human Health Risk Assessment for
the Reregistration Eligibility Decision Document (RED), dated July 31, 2006, and RevisedEFED RED
Chapter for Malathion, dated October, 2000. The purpose of this summary is to assist the reader by
identifying the key features and findings of these risk assessments, and to help the reader better
understand the conclusions reached in the assessments.
The human health and ecological risk assessment documents and supporting information
listed in Appendix C were used to reach the safety finding and regulatory decision for malathion.
While the risk assessments and related addenda are not included in this document, they are available
from the OPP Public Docket EPA-HQ-OPP-2004-0348 and may also be accessed on the internet at
Mtp;//wwwjeguiatlons,gQY
A. Human Health Risk Assessment
The human health risk assessment incorporates potential exposure risks from all sources,
which include food, drinking water, residential (if applicable), and occupational scenarios.
Aggregate assessments combine food, drinking water, and any residential or other non-occupational
(if applicable) exposures to determine potential exposures to the U.S. population. The Agency's
human health assessment is protective of all U.S. populations, including infants and young children.
The Agency's use of human studies in the malathion risk assessment is in accordance with the
Agency's Final Rule promulgated on January 26, 2006, related to Protections for Subjects in
Human Research, which is codified in 40 CFR Part 26.
The EPA released its revised risk assessments for malathion for public comment on
September 23, 2005 for a 60-day public comment period (and additional Phase 5 of the public
participation process). In response to comments received and additional data submitted during
Phase 5, the risk assessments were updated. The revised risk assessments may be found in the OPP
public docket at the address given above and in EPA's electronic docket under docket number EPA-
HQ-OPP-2004-0348. Major revisions to the malathion human health risk assessment include the
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following:
• Revised Toxicity Adjustment Factor: revision based on recalculation of the doses
administered to the test animals in the original data set.
• New chronic dietary endpoint: revised chronic dietary endpoint also based on the
recalculation of the doses administered to the test animals in the original data set.
• New dermal toxicity endpoint: new data were voluntarily submitted by the technical
registrant, reviewed by the Agency, and incorporated into the current assessment.
For more information on the malathion revised human health risk assessment, see Malathion:
Revised Human Health Risk Assessment for the Reregistration Eligibility Decision Document (RED).,
dated July 31,2006.
1. Toxicity Summary
The toxicity (hazard) assessment is designed to predict whether a pesticide could cause
adverse health effects in humans, including short-term (acute) effects, or lifetime (chronic) effects at
the level or dose which is expected to occur through the labeled use. The Agency has reviewed all
the toxicity data submitted for the reregi strati on of malathion and has determined that the
toxicological database is sufficient to assess potential hazard to all population subgroups, including
infants and children, under various exposure scenarios and time durations. The only toxicity data
gaps for malathion are a special acute and repeated dose comparative cholinesterase assay with
malathion and malaoxon, the environmental degradate of malathion, in juvenile rats, and an
immunotoxicity study. The Agency issued a Data Call-In in October, 2004 requiring the special
cholinesterase assay. The immunotoxicity study will be required as part of this RED.
Malathion (O,O-dimethyl thiophosphate of diethyl mercaptosuccinate) is an
organophosphorous insecticide, which targets the nervous system and, like all members of this
class, displays its mode of toxic action through inhibition of cholinesterase (ChE). Malathion is
converted to its metabolite, malaoxon (via oxidation of the P=S moiety to P=O), in insects and
mammals. The oxon is the active ChE inhibiting metabolite of malathion. When administered to
animals directly, malaoxon is a more potent ChE inhibitor than malathion. Cholinesterase
inhibition (ChEI) in the nervous system, from exposure to malathion, has been measured in various
compartments and observed in multiple species (rat, mouse, rabbit, and dog), following oral,
dermal, and inhalation routes of administration. Other treatment related effects of malathion
include histopathologic lesions of the nasal cavity and larynx, following inhalation. For a complete
discussion on the toxicological database on malathion, see Malathion: Revised Human Health Risk
Assessment for the Reregistration Eligibility Decision Document (RED)., dated July 31, 2006.
Data from chronic studies revealed ChEI effects at the lowest doses tested. In standard
guideline prenatal developmental toxicity studies, no developmental toxicity was observed in rats.
The weight of evidence from guideline studies and open literature does not support a mutagenic
concern for malathion. Published literature studies have shown that malathion can affect immune
function, depending on route, magnitude, and frequency of administration. This information has
prompted the requirement for a guideline immunotoxicity study to better characterize the potential
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effects of malathion on the immune system, which will be required as part of this RED.
a. Acute Toxicity Profile
Malathion exhibits low acute toxicity via the oral, dermal, and inhalation routes (Toxicity
Category III or IV). It exhibits only slight eye and dermal irritation and is not a dermal
sensitizer. Table 1 provides a summary of the toxicity categories for malathion.
Table 1. Malathion Acute Toxicity Profile
Guideline Number
870.110
870.1200
870.1300
870.2400
870.2500
870.2600
Type of Study - Species
Acute Oral - Rat
Acute Dermal - Rat
Acute Inhalation - Rat
Eye Irritation - Rabbit
Skin Irritation - Rabbit
Dermal Sensitization -
Guinea pig
MRID
(Date)
00159876
(1986)
00159877
(1986)
00159878
(1986)
00159880
(1985)
00159879
(1985)
00159881
(1986)
Results
LD50= 5400(M)/5700(F) mg/kg
LD50 >2000 mg/kg (M)(F)
LC50> 5.2 mg/L (M)(F)
Slight conjunctiva! irritation;
Clear by 7 days
Slight dermal irritation
(PIS=1.1)
Not a skin sensitizer
Toxicity
Category
IV
III
IV
III
IV
N/A
LD50 or LC50; Median Lethal Dose or Concentration, statistically derived single dose or concentration that can be
expected to cause death in 50% of the test animals when administered by the route indicated (oral, dermal,
inhalation).
b. FQPA Safety Factor Considerations
The Federal Food, Drug, and Cosmetic Act (FFDCA), as amended by FQPA, directs the
Agency to use an additional tenfold (lOx) safety factor (SF) to account for potential pre- and
post-natal toxicity and completeness of the data with respect to exposure and toxicity to infants
and children. FFDCA authorizes the Agency to reduce the lOx FQPA SF only if reliable data
demonstrate that the resulting margin of exposure is adequate to protect infants and children.
The toxicology database for malathion is adequate although data gaps remain: a guideline
immunotoxicity study and a special comparative ChEI study for acute and repeated exposures in
juvenile animals with malaoxon and malathion.
The data the Agency used to address potential differences between young and adult
animals are the following guideline studies: pre-natal developmental toxicity in rats and rabbits;
a two-generation reproductive toxicity study in rats; an acute neurotoxicity study in rats ; a sub-
chronic neurotoxicity study in rats; and a developmental neurotoxicity study in rats (with a
-------
supplemental range-finding study). Additionally, a comparative ChE study with malathion in
adult and immature rats for acute and repeated exposures is also available. Consistent with its
mode of action, ChE inhibition provides the critical effect for determining the point of departure
for the oral, dermal and inhalation (aggregate only) routes of exposure. The comparative ChE in
the young demonstrate that juvenile animals are more sensitive than adults.
In order to account for the increased toxicity due to exposure from malaoxon, the Agency
is applying a Toxicity Adjustment Factor (TAP) of 61x to malaoxon exposures. The Agency has
data on malaoxon (including a 14-day and 2-year feeding study in rats) for repeated exposures
which shows malaoxon to be 61x more toxic to adults than malathion. This TAP is, in the
absence of data, assumed to be health protective in assessing single (acute) exposures to
malaoxon in adults as well as both acute and repeated exposures to the young. The Agency will
be receiving confirmatory acute and repeated dose toxicity data for the young in the near future,
as discussed earlier.
The Agency has determined that there is evidence that following acute or repeated dose
exposures to malathion, young animals exhibit adverse effects more readily than adults. The
Agency has oral data for this most sensitive subpopulation and is using it to determine the
appropriate point of departure (PoD) for use in assessing risk for acute and chronic dietary and
incidental oral scenarios. In those instances where the Agency is using a PoD derived on pup
data, the FQPA SF is reduced to Ix. The Agency has decided to retain the FQPA SF (lOx) for
those scenarios where the PoD does not already reflect the most sensitive population (i.e., the
PoD is derived from adult animal studies). Consequently, for dermal exposure scenarios, where
the PoD is derived from adult animals and children are expected to be exposed, the FQPA SF of
lOx has been retained. Similarly, for inhalation exposure scenarios where the endpoint selected
is ChE inhibition (in order to aggregate non-occupational exposures) and the PoD is based on
adult animals, the FQPA SF of lOx has also been retained. Finally, the Agency has retained the
FQPA SF of lOx for the bystander inhalation scenario in order to account for the lack of a
NOAEL, severity of effect, as well as any differential in susceptibility in the young.
Although the immunotoxicity study is identified as a data gap, it is not considered
important to the quantification of risk from malathion. Rather it will be used to further
characterize the hazard from malathion in terms of its effects on the immune system, and it is not
expected to have an effect on the hazard values used in the risk assessment. Therefore, no
additional safety factor is necessary to account for the lack of a guideline immunotoxicity study.
FQPA also requires that the completeness of the exposure data base be considered in
deciding whether to retain, reduce or remove the FQPA SF. The Agency is confident that the
risk assessment for each potential exposure scenario will not underestimate dietary or non-
occupational exposures to infants and children.
c. Dose-Response and Benchmark Dose Analysis
10
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A means of refinement to the use of no observed adverse effect levels (NOAELs) and
lowest observed adverse effect levels (LOAELs) to describe the relationship between dose and
response is the use of benchmark dose (BMD) modeling. BMD modeling is a statistically more
robust approach, which better incorporates all the data from the test animals at all doses, thus
characterizing response (from 0% - 100% inhibition) along the dose continuum.
For malathion, BMD modeling was utilized for the malathion comparative ChE study,
(used for endpoint selection for the acute and chronic dietary, and incidental oral scenarios), and
21-day dermal studies (used for endpoint selection for the dermal occupational and non-
occupational exposure scenarios). In the past, the Agency has selected the point at which 10%
ChEI is observed (BMDio) as the point of departure (PoD) i.e, the point of biological and
statistically significant response to a chemical exposure. The Agency then determines the 95%
lower confidence limit associated with the PoD to select the toxicity endpoint value, which is
termed the BMDL. Thus the BMDLio is the lower 95% confidence interval associated with the
dose determined to cause 10% inhibition in the test animals. Although previous PoDs were
based upon the BMDio, the Agency may consider alternative benchmark response levels (greater
or lower than 10% inhibition) on a chemical by chemical basis, provided there is sufficient
information to ensure that the appropriate and protective response level is chosen.
The technical registrant provided comments and analysis to the Agency suggesting that
the 20% response level (20% ChEI) was both statistically and biologically more appropriate than
the 10% ChEI level, due to the variability associated with ChEI measurements in the red blood
cell (RBC) compartment. The Agency reviewed the relevant data and concluded that a 20%
RBC ChEI (BMD2o) in the malathion adult animal is protective of obvious clinical signs in adult
animals, and an appropriate PoD for dermal exposure. Therefore, the Agency selected the
BMDL20 dose (127 mg/kg/day) from the data set as the dermal toxicity endpoint. The Agency
also considered the technical registrant's analysis regarding a BMD20 for dietary exposure.
However, after reviewing the relevant data, the Agency determined that the BMD20 for dietary
exposure was not protective, and that the BMDLio is the appropriate and protective endpoint for
dietary and incidental oral exposure. Further information on BMD modeling is contained in the
Malathion: Revised Human Health Risk Assessment for the Reregistration Eligibility Decision
Document (RED), dated July 31, 2006
d. Toxicological Endpoints
The toxicological endpoints used in the human health risk assessment for malathion are
listed in Table 2, below. The uncertainty factors (UF) which account for interspecies
extrapolation (lOx), intraspecies variability (lOx), and the FQPA SF used to account for
susceptibility of infants and children, are also described in Table 2.
Table 2. Summary of Toxicological Endpoints
11
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Exposure
Scenario and
Population
Dose (mg/kg/day) and
Uncertainty Factor or
FQPA Safety Factor
Level of Concern (LOG) as
either Population Adjusted
Dose (PAD) or Margin of
Exposure (MOE)
Study and Toxicological Effects
Dietary Exposure
Acute Dietary
Females 13-49
There is no increased susceptibility expected to females of child-bearing age. Effects observed in the
rat and rabbit developmental studies showed reduced body weight gains with NOAELs of 400 and 25
mg/kg/d, respectively. The aRfD for the general population is lower and, thus, would be protective of
this population group.
Acute Dietary
General population,
including infants
and children
Oral
BMDL10 = 13.6 mg/kg/d
UF = 1002
FQPA SF = Ix
RfD = dose/UF
Acute RfD = 0.14 mg/kg/day
aPAD = acute RfD/FQPA SF
aPAD = 0.14 mg/kg/day
BMDL10 = 13.6 mg/kg/day based on
RBC ChEI in male pups from the
comparative ChE acute oral study in the
rat.
FQPA SF = Ix since dose is taken from
pup data, susceptibility of young is
accounted for.
Chronic Dietary
All populations
Oral
BMDL10= 7.1 mg/kg/d
UF = 100
FQPA SF = IX
RfD = dose/UF
Chronic RfD = 0.07
mg/kg/day
cPAD = chronic RfD/FQPA
cPAD = 0.07 mg/kg/day
BMDL10 = 7.1 mg/kg/d based on RBC
ChEI in offspring from the comparative
ChE multiple dose oral study in the rat.
FQPA SF = Ix since dose is taken from
the pup data, susceptibility of young is
accounted for.
Non-Dietary Exposure
Incidental Oral
Short- (1-30 days)
and Intermediate-
Term (1-6 months)
Children
Oral
BMDL10 =7.1 mg/kg/d
UF = 100
FQPA SF = Ix
Residential LOC = UF x
FQPA SF
Residential (Short-term only)
LOC for MOE = 100
Occupational = N/A
BMDL10 = 7.1 mg/kg/d based on RBC
ChEI in offspring from the comparative
ChE multiple dose oral study in the rat.
FQPA SF = Ix since dose is taken from
pup data, susceptibility of young is
accounted for.
Dermal
Short- (1-30 days)
and Intermediate-
Term (1-6 months)
Children
Dermal
BMDL20 = 127 mg/kg/d
UF = 100
FQPA SF = lOx
Residential LOC = UF x
FQPA SF
Residential (Short-term only)
LOC for MOE = 10003
Occupational = N/A
BMDL20 = 127 mg/kg/d based on RBC
ChEI (%) in two separate 21-day dermal
studies in rabbits
FQPA SF = lOx since dose is taken from
adult data.
12
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Exposure
Scenario and
Population
Dose (mg/kg/day) and
Uncertainty Factor or
FQPA Safety Factor
Level of Concern (LOG) as
either Population Adjusted
Dose (PAD) or Margin of
Exposure (MOE)
Study and Toxicological Effects
Dermal
Short- (1-30 days)
and Intermediate-
Term (1-6 months)
Adults
Dermal
BMDL20 = 127 mg/kg/d
UF = 100
FQPA SF = Ix1
Residential LOC = UF x
FQPA SF
Residential (Short-term only)
LOC for MOE = 100
Occupational
LOC for MOE =100
BMDL20 = 127 mg/kg/d based on RBC
ChEI (%) in two separate 21-day dermal
studies in rabbits
FQPA SF =lx since population of
concern is adults
Inhalation
Short- (1-30 days)
and Intermediate-
Term (1-6 months)
All populations
Inhalation
LOAEL = 0.1mg/L
(25.8 mg/kg/day)
UF = 100
FQPA SF = lOx
Residential LOC = UF x
FQPA SF
Residential (Short-term only)
LOC for MOE =1000
LOAEL = 0.1 mg/L (25.8 mg/kg/d)
based on histopathology in respiratory
epithelium 90-day inhalation study in
rats.
FQPA SF = lOx to account for LOAEL
to NOAEL extrapolation and severity of
effect (due to concern for exposure to
infants and children)
Inhalation
LOAEL = 0.1 mg/L
(25.8 mg/kg/day)
UF = 10004
Occupational
LOC for MOE = 1000
LOAEL = 0.1 mg/L (25.8 mg/kg/d)
based on histopathology in respiratory
epithelium 90-day inhalation study in
rats.
Inhalation
Short- (1-30 days)
and Intermediate-
Term (1-6 months)
Children -
Aggregate Only
Inhalation
NOAEL=0.1mg/L
(25.8 mg/kg/day) based
on ChEI
UF = 100
FQPA SF = lOx
Residential LOC = UF x
FQPA SF
Residential (Short-term only)
LOCforMOE=10003
Occupational = N/A
LOAEL = 0.45 mg/L (115 mg/kg/day)
based on plasma and RBC ChEI 90-day
inhalation study in rats.
FQPA SF = lOx since the dose is taken
from adult animals.
13
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Exposure
Scenario and
Population
Inhalation
Short- (1-30 days)
and Intermediate-
Term (1-6 months)
Adults - Aggregate
Only
Cancer
Dose (mg/kg/day) and
Uncertainty Factor or
FQPA Safety Factor
Inhalation
NOAEL = 0.1mg/L
(25.8 mg/kg/day) based
on ChEI
UF = 100
FQPA SF = Ix1
Level of Concern (LOC) as
either Population Adjusted
Dose (PAD) or Margin of
Exposure (MOE)
Residential LOC = UF x
FQPA SF
Residential (Short-term only)
LOC for MOE = 100
Occupational
LOC for MOE =100
Study and Toxicological Effects
LOAEL = 0.45 mg/L (115 mg/kg/day)
based on plasma and RBC ChEI 90-day
inhalation study in rats.
FQPA SF = Ix since population of
concern is adults.
Classification: Suggestive evidence of carcinogenicity
UF = uncertainty factor, FQPA SF = FQPA safety factor, NOAEL = no observed adverse effect level, LOAEL = lowest
observed adverse effect level, PAD = population adjusted dose (a = acute, c = chronic), RfD = reference dose, MOE =
margin of exposure, LOG = level of concern, NA = Not Applicable, RED = red blood cell, ChEI = cholinesterase inhibition,
BMDL10 = Benchmark Dose Lower Limit (lower 95% confidence limit on the RBC ChEI 10% effect level, BMDL20 =
Benchmark Dose Lower Limit (lower 95% confidence limit on the RBC ChEI 20% effect level)
1: The FQPA SF has not been retained for women of child-bearing age following dermal and/or inhalation exposure
because: (i) the observed susceptibility differences between young and old are a result of postnatal exposures and
ChEI data from gestational only exposures which indicate that fetuses are less sensitive than the mother at birth; (ii)
the dermal toxicity endpoint is based on the more sensitive species (rabbit); (iii) in dermal and inhalation studies,
females were neither more sensitive nor responded differently than males; and, (iv) oral studies indicate that there is
no enhanced sensitivity of pregnant animals versus non-pregnant animals to malathion, and there is no reason to
believe that this is route-specific.
2: UF = 100 [lOx for interspecies and a lOx for intraspecies variations].
3: MOE = 1000 [lOx for interspecies extrapolation, lOx for intraspecies variations, and lOx for known susceptibility
of the young based on the malathion comparative ChE study].
4: UF = 1000 [lOx for interspecies extrapolation, lOx for intraspecies variations, and lOx for a LOAEL to NOAEL
extrapolation and for the severity of the effect.]
e. Toxicity Adjustment Factor for Malaoxon
Under certain environmental conditions, humans may be directly exposed to malaoxon
following applications of malathion (i.e., when malathion undergoes oxidation and the P=S
moiety is converted to a P=O moiety). As the oxon metabolite, malaoxon is a more potent ChE
inhibitor. The Agency characterizes the toxicity of the metabolite in terms of its degree of
potency in comparison to the parent compound. The ratio of relative toxicity between the parent
and the oxon is termed the Toxicity Adjustment Factor (TAP).
To calculate the ratio of toxicity between malathion and malaoxon, the Agency utilized
BMD modeling of the data. Ideally, a separate TAP for acute/short-term and chronic/long-term
exposures would be determined. At the present time, the Agency does not have sufficient data to
calculate an acute TAP, but sufficient data with which to estimate a chronic TAP does exist (i.e.,
14-day rat study and 2-year chronic rat study). The Agency issued a Data Call-In in October,
14
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2004 which will result in the submission of a special acute and repeat dose comparative
cholinesterase assay with malaoxon and malathion in juvenile animals, which will be used to
determine the acute TAP. In the absence of an acute TAP, the Agency has applied the chronic
TAP to acute exposure scenarios. Based on BMD modeling, the chronic TAP is 61x, meaning
malaoxon is estimated to be 61 times more toxic than malathion. Therefore, in the absence of an
acute TAP, the chronic TAP of 61x calculated from oral studies is applicable to residues of
malaoxon for risk assessment of all exposure durations, routes, and scenarios and is considered
to be health protective.
f. Carcinogenicity
Malathion has been classified as having "suggestive evidence of carcinogenicity" in
accordance with the EPA Proposed Guidelines for Carcinogen Risk Assessment (July 1999). A
quantitative cancer dose-response assessment is not indicated for pesticides in the "suggestive"
category.
The classification is based on the following evidence: 1) the occurrence of liver tumors in
mice and rats only at excessive doses; 2) the presence of a few rare tumors in rats, which cannot
be distinguished as either treatment related or due to random occurrence; 3) the evidence for
mutagenicity is not supportive of a mutagenic concern in carcinogenicity; and 4) malaoxon, a
structurally related chemical, is not carcinogenic in rats. The carcinogenic potential of malathion
was also reviewed by the FIFRA Scientific Advisory Panel (SAP) on August 17-18, 2000. The
Panel report, "A Consultation on the EPA Health Effects Division's Proposed Classification of
the Human Carcinogenic Potential of Malathion" dated December 14, 2000, offers an overall
equivocal recommendation on the Agency's classification of malathion as "suggestive." The
Agency subsequently considered the SAP recommendations and concluded that the cancer
classification should remain as "suggestive." Additionally, the CARC recently evaluated a
publication by Cabello et al. (2001) and concluded that the paper provided insufficient basis for
revising the cancer classification for malathion. Furthermore, the chronic dietary risk assessment
is considered protective of any potential carcinogenic effects.
2. Endocrine Disruption
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 recommendations of its Endocrine Disrupter and Testing Advisory Committee
(EDSTAC), EPA determined that there was a scientific basis 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,
15
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FFDCA authority to require the wildlife evaluation. As the science develops and resources
allow, screening of additional hormone systems may be added to the Endocrine Disrupter
Screening Program (EDSP). When additional appropriate screening and/or testing protocols
being considered under the Agency's EDSP have been developed, malathion may be subject to
further screening and/or testing to better characterize effects related to endocrine disruption.
In the available toxicity studies on malathion, there was no estrogen or androgen
mediated toxicity. Thyroid effects were observed in the combined chronic/carcinogenicity study
in rats, which included an increase in parathyroid hyperplasia in male and female rats, and a
significant trend in thyroid follicular cell adenomas and/or carcinomas and thyroid c-cell
carcinomas (all in males). However, the FIFRA SAP did not consider the thyroid effects of
concern or necessarily related to malathion exposure (SAP, 2000).
3. Dietary Exposure from Malathion and Malaoxon in Food
EPA conducted highly refined acute (probabilistic) and chronic dietary (food) risk
assessments for malathion using Dietary Exposure Evaluation Model software with the Food
Commodity Intake Database (DEM-FCID™, Version 2.03), which uses food consumption data
from the U.S. Department of Agriculture's Continuing Survey of Food Intakes by Individuals
(CSFII) from 1994-1996, and 1998. The acute and chronic dietary risk assessment was
conducted for all supported malathion food uses.
Malathion dietary residue estimates reflect use of monitoring data, processing factors,
and percent crop treated. Pesticide residue data are drawn from several sources: USDA's
Pesticide Data sampling Program (PDF) between 1999-2003; FDA's surveillance program; the
FOODCONTAM database (designated FODC) between 1992-1998; and field trial data for
malathion and malaoxon. The four residue data sources analyzed for both malathion and
malaoxon provide EPA with residue data on more than 40,000 food sample items. Residue data
is combined with consumption data to estimate potential dietary exposure on an acute (one-time),
and chronic basis.
As the major metabolite, malaoxon is to be regulated in plant commodities. The
formation of malaoxon can occur via oxidation during water treatment processes (discussed
below), or through reaction with the ambient air. Data suggest though, that the oxidation of
malathion to malaoxon via ambient air does not readily occur on biologically active material
(plant surfaces). Indeed, within the more than 40,000 residue samples collected between 1992-
2003, only 43 detections of malaoxon were made. Although detections of malaoxon in or on
food commodities are infrequent, they are accounted for in the Agency's dietary assessment by
multiplying each malaoxon detection by the TAP (61x) and adding this value to the malathion
dietary residue values.
a. Population Adjusted Dose
16
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The dietary risk assessment incorporates both exposure and toxicity of a given pesticide.
For acute and chronic dietary assessments, the risk is expressed as a percentage of a level of
concern (i.e., the dose predicted to result in no unreasonable adverse health effects to any human
sub-population, including sensitive members of such sub-populations). This level of concern is
referred to as the Population Adjusted Dose (PAD). Dietary risk is characterized in terms of the
PAD, which reflects the Reference Dose (RfD), either acute or chronic, that has been adjusted to
account for the FQPA SF. The Agency reduced the FQPA SF to Ix where the endpoint is
derived from data using juvenile animals, i.e., for both the aPAD and cPAD. Both the acute and
chronic PADs for malathion are protective of all population subgroups including all infants,
children, and women of child bearing age.
Estimated dietary risks less than 100% of the PAD, either acute (aPAD) or chronic
(cPAD), are below the Agency's level of concern (LOG). The aPAD is the dose at which a
person could be exposed at any given day with no adverse health effects expected. The cPAD is
the dose at which an individual could be exposed over the course of a lifetime with no adverse
health effects expected.
b. Acute and Chronic Dietary (Food) Risk
The estimated acute and chronic dietary risks from malathion and malaoxon, in food
alone, are less than 100% of both the aPAD and the cPAD and, therefore, are below the
Agency's LOG. Acute dietary exposure to malathion and malaoxon in food at the 99.9th
percentile is 5% of the aPAD for the general U.S. population, and 11% of the aPAD for infants
(<1 yr old), the most highly exposed population subgroup. The chronic dietary (food) exposure
to malathion and malaoxon is less than 1% of the cPAD for all population subgroups. Tables 3
and 4 below summarize the acute and chronic dietary (food only) risks, respectively, from
dietary exposure to food alone.
Table 3. Acute Dietary Exposure and Risk at the 99.9th Percentile - Food Only
Population Subgroup
General U.S Population
All Infants < 1 year old
Children 1-2 years old
Children 3-5 years old
aPAD
(mg/kg/day)
0.14
0.14
0.14
0.14
Exposure
(mg/kg/day)
0.006975
0.015734
0.013100
0.012432
Percent of the aP AD
5
11
9
9
Table 4. Chronic Dietary Exposure and Risk - Food Only
Population Subgroup
General U.S Population
cPAD
(mg/kg/day)
0.07
Exposure
(mg/kg/day)
0.000148
Percent of the cP AD
<1
17
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Population Subgroup
All Infants < 1 year old
Children 1-2 years old
Children 3-5 years old
cPAD
(mg/kg/day)
0.07
0.07
0.07
Exposure
(mg/kg/day)
0.000219
0.000343
0.000334
Percent of the cP AD
<1
<1
<1
c. Drinking Water Exposure
Exposure to pesticides from drinking water can occur through surface and groundwater
contamination. The Agency considers both acute (one day) and chronic (long-term) drinking
water risks and uses either modeling or actual monitoring data, if available. EPA has assessed
potential dietary risk from exposure to concentrations of malathion and malaoxon in surface
water and groundwater sources of drinking water, using both modeling and available monitoring
data.
Although malathion has some mobility characteristics which suggest it may leach into
groundwater, its short soil persistence in conjunction with its relatively quick degradation
reduces this potential exposure. EPA's groundwater database (EPA Pesticides in Ground Water
Data Base 1971-1991, National Summary) identified very few wells with positive detections of
malathion (12 of 990 sampled). Based upon its review of the monitoring data, EPA selected 3.17
ppb to be used for dietary exposure for malathion and malaoxon via groundwater in earlier
assessments. The selected value of 3.17 ppb is considered to be a much more conservative value
than concentrations predicted through EPA's Tier I SCI-GROW model (0.142 ppb).
Malathion's solubility gives it the potential to dissolve in rainwater and be transported in
runoff from the application site. Surface water monitoring data on malathion has been collected
in connection with the Boll Weevil Eradication Program and the Mediterranean fruit fly
(Medfly) control programs, and is consistent with the fate data. These monitoring data indicate
that malathion is mobile, but also that concentrations of malathion in surface water runoff
decrease as distance from the application site increases. This result was expected since a greater
distance (from the application site) allowed malathion to penetrate soil, adsorb to soil particles,
or break/down via hydrolysis and/or aquatic metabolism. Both the fate and the monitoring data
indicate that potential runoff of malathion in agricultural settings is affected by numerous
variables, including soil type, soil half-life, the amount of time between rainfall events, the
amount of rainfall, and the vegetation.
To model potential runoff concentrations from agricultural uses of malathion, EPA used
the Tier II Pesticide Root Zone Model (PRZM), and Exposure Analysis Modeling System
(EXAMS). EPA selected 16 separate crop scenarios for PRZM-EXMS in order to represent the
100+ commercial agricultural sites for which malathion is registered. EPA selected the 16 crop
surrogates based upon: geographic location, use information, percent crop treated, and crop
type. The modeling reflected the "Index Reservoir" (IR), a modeled water body with physical
18
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dimensions drawn from an actual reservoir, and Percent Cropped Area (PCA) refinements. PCA
factors are used in pesticide drinking water assessments to account for the fact that the entire area
of an individual watershed is not devoted to growing crops. In addition, other refinements were
also considered in the models, including a refined aerobic soil half-life and an adjusted first
application date. In addition, mitigated application values were modeled. Mitigated application
values reflect a lower application rate (Ib ai/A), and/or a reduction in the number of applications
per year. Table 5 below summarizes selected input parameters used in estimating EDWCs. The
Agency generated estimated drinking water concentrations (EDWCs) using both default and
refined model inputs. Since the estimated residues of malathion in surface water are greater than
those predicted or measured in groundwater, the Agency is only presenting dietary exposure to
malathion/malaoxon via the surface water route, as this will be protective of any potential
groundwater exposure to malathion.
Table 5. Selected Input Parameters for Drinking Water Modeling
Default
Refined
Soil
Half-Life
3 day
Iday1
Percent
Cropped
Area (PCA)
National
default (0.87)
Regional
PCAs2
Application
Method
Ground and
Aerial
Ground and
Aerial
First Application
Date
Rainiest part of the
year, depending upon
scenario modeled3
Typical first
application date4
Use Pattern
(app. rate and no. of
appls./year)
Maximum supported
Proposed (reduced)
application values
1: Under certain soil conditions, malathion aerobic half-life may be 24 hours.
2: Regional PCAs used: Southeast (0.38); Central (0.80); Western (0.56); and, North West (0.63).
3: Default first application date is intended to reflect month with heaviest rainfall in the modeled area: southeast
(May 1); central (Jan. 1); northwest (Jan. 1).
4: "First application date" was needed only to refine the model scenario for strawberry grown in CA (May 1).
Refined Input Parameters
The drinking water models used in this analysis require the input of a single aerobic soil
metabolism half-life for the entire modeled period. A 1-day aerobic soil metabolism half-life
was modeled along with the 3-day half-life to evaluate the effect of a shorter soil half-life.
Malathion has a wide range of measured soil half-lives which roughly correlate with soil
microbial activity and moisture. On moist, microbially active soils, malathion is expected to
degrade faster than on dryer, less microbially active soils. The drinking water modeling using a
1-day half-life may represent more typical water concentrations than the default 3-day half-life,
because agricultural soils would be expected to commonly be moist and microbially active in
order to support crop growth. For all but one scenario (WA cherry), estimated acute dietary risks
were below the Agency's LOG, when the mitigated application values and the Regional PCAs
were used to model EDWCs. For the WA cherry scenario, the Agency used the refined 1-day
soil half-life, because it appropriately represents the northwest region where rainfall and soil
moisture is higher.
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PCA factors are used in pesticide drinking water assessments to account for the fact that
the entire area of an individual watershed is not devoted to growing crops. The default national
PCA of 0.87 is based on the most heavily-cropped watershed in the entire United States, which is
located in the Midwest. However, many crops to which malathion is applied are grown in less
extensively cropped areas. For this reason, regional PC As, which represent a refinement of
national PCAs, were also used in this assessment. Even when considered on a regional scale,
regional PCA factors are still likely to be conservative, as they represent the percentage of the
most heavily-cropped watershed that is planted to any crop, not just the crop considered in a
particular drinking water scenario. PCAs also do not take into account the percentage of a
particular crop that is actually treated with malathion. State-level usage data indicate that
malathion is generally used on a relatively small portion of any given crop (<5%); thus, the
probability that malathion is applied to a large portion of a watershed is decreased.
In the absence of information on the time of year when malathion is used for pest control
on a particular crop, the rainiest season for a site was chosen to reflect high-end runoff and
exposure values. The Agency can also consider alternate application timings if information is
available that indicates the rainiest season for a particular site does not coincide with malathion
use. In this instance, a refined first application date for malathion was used for strawberries
grown in California, because specific information about its use pattern and timing of application
was available to the Agency.
Malathion Conversion to Malaoxon in Drinking Water
As mentioned above, malaoxon is formed during the water treatment process. The rate of
conversion during water treatment is efficient, but may vary depending on the type of water
process used in disinfection. Limited monitoring information indicates that conversion from
malathion to malaoxon may be as high as 100%; data collected by the FL Dept. of Agriculture
and Consumer Services Bureau of Pesticides (1997) showed only concentrations of malathion
entering the Hillsboro Water Treatment Plant and, following the treatment process, only
concentrations of malaoxon exiting the plant. Once converted, malaoxon may remain stable in
treated water long enough to be available at the tap for direct consumption. Recently received
hydrolysis data indicates that malaoxon may remain stable for 72 hours, which is within delivery
times for some publicly owned treatment works (POTWs).
Therefore, in assessing dietary risk to malathion from drinking water, the Agency
conservatively assumes that all estimated concentrations of malathion which enter surface water
from agricultural runoff are converted to malaoxon and are available for dietary exposure via
drinking water. EPA incorporated malathion/malaoxon EDWCs into the acute and chronic
dietary assessments by applying the TAF (61x) to the concentrations and including this exposure
with the malathion (and malaoxon) food residue values in the DEEM model.
The drinking water assessment contains various refined and conservative assumptions.
Overall though, the Agency believes that estimated dietary risk via drinking water is not
20
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underestimated. The Agency notes that certain assumptions in its assessment potentially
overestimate the dietary exposure to malathion/malaoxon. First, both environmental fate data
and monitoring data indicate the malathion breaks down as it moves farther from the application
source; however, the Agency has assumed that 100% of the predicted concentration value at the
"edge of the field" reaches the POTW. Second, the Agency has little data to fully characterize
the conversion of malathion to malaoxon in the water treatment process. While the Agency has
data to support the upper-bound conversion of malathion to malaoxon as 100%, it lacks data to
characterize a lower-bound rate of conversion which, under certain conditions, the Agency
believes would be less than the assumed 100% conversion. Thirdly, the Agency's drinking water
model is designed to predict surface water runoff from large portions of a watershed treated with
a compound at the same time. However, State level malathion usage data indicates that
malathion is generally used on a relatively small portion of any given crop. Therefore, even
EDWCs generated with a refined regional PC A may be an overestimate. Finally, the Agency's
TAP (61x), derived from chronic toxicity data could be an overestimate since acute toxicity data
on malaoxon is outstanding. Table 6 presents the acute EDWCs and the types of refinements
used for the malathion drinking water assessment. For more information on EDWCs refer to
Drinking Water Exposure Modeling Evaluating the Effect of Varying Crop Scenarios,
Application Rate, Application Interval, Spray Drift Levels, Soil Half Life (June 15, 2006).
Table 6. Summary of Acute EDWCs for Selected1 Malathion Model Scenarios
Site
Lettuce, CA
Peach, TX
Citrus, FL
Strawberry, CA
Cherry, WA
Asparagus, WA
EDWCs (ppb): Default
Input Parameters and
Maximum Use Patterns
141
185
154
107
44
23
EDWCs (ppb): Refined
Input Parameters and
Mitigated Use Patterns
12.5
25.4
14
3.9
19.5
17.1
Refinements Applied to Default
EDWC
Default estimate was refined with:
- proposed application values,
- regional PCA, and,
- 1 day half-life.
Default estimate was refined with:
- proposed application values,
- regional PCA2
Default estimate was refined with:
- proposed application values
Default estimate was refined with:
- first application date, and,
- regional PCA
Default estimate was refined with:
- regional PCA
- 1 day soil half life
Default estimate was refined with:
- regional PCA
1: EPA modeled 16 crop scenarios to assess drinking water exposure. Only those which exceeded the Agency's
LOG when default input parameters were used are shown here, and refinements implemented.
2: An adequate Peach, TX modeling scenario was unavailable; therefore, EPA combined southcentral PCA with GA
Peach modeling scenario.
Chronic EDWCs for Malathion
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The chronic EDWC used to assess malathion/malaoxon in surface water sources of
drinking water was also estimated using the PRZM/EXAMS screening-level model. Based on
the CA lettuce scenario, with a 3-day default half-life at the current maximum application rate,
the l-in-10 year annual concentration of 3.62 ppb was used in the chronic dietary exposure
assessment.
4. Residential Exposure and Risk
Residential exposure assessments consider all potential non-occupational pesticide
exposure, other than exposure due to residues in foods or in drinking water. Exposures to
malathion may result from outdoor residential uses on vegetable gardens, home orchards,
ornamentals and perimeter residential treatments. Residential exposure also may occur from use
of malathion in wide-area treatments for adult mosquito control, spray drift from agricultural
uses and fruit fly (Medfly) control.
The Agency has determined that there is a potential for exposure to malathion in
residential settings for homeowners who handle (mix, load, and apply) products containing
malathion. The Agency has also determined that there are potential post-application exposures
to residents contacting residues while performing work associated with treating home vegetable
gardens and fruit/nut trees, harvesting strawberries in commercial "pick-your-own" fields, and
following outdoor fogger use.
Because of the unique circumstances regarding the special uses of malathion in public
health mosquito abatement programs, the USDA's Boll Weevil Eradication Program, and fruit
fly (Medfly) control, potential residential bystander exposure from these uses are assessed in
separate sections later in this document. The greatest potential for malaoxon formation occurs
when malathion residues deposit on hard, dry surfaces which can be inadvertently contaminated
during wide area applications. For these reasons, the Agency believes that residential contact
with outdoor hard surfaces following wide area aerial application of malathion presents the most
relevant and worst-case scenario for assessing the risk from malaoxon exposure. Specifically,
the Agency has estimated toddler post-application exposures from potential contact with
malaoxon residues on wood decks and playground equipment following aerial ULV sprays for
public health mosquito treatment, boll weevil eradication, and fruit fly treatment.
To estimate residential dermal and inhalation risks, the Agency calculates a margin of
exposure (MOE), which is the ratio of the point of departure (PoD) selected for risk assessment
to the exposure. The MOE is compared to a level of concern which is the same value as the
uncertainty and safety factors (UF) applied to a particular toxicity study. For a summary of
doses, UFs and FQPA SFs used to assess residential exposures, please refer to Table 2.
Residential Use Patterns
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The technical registrant (Cheminova) has indicated the following residential use sites will
not be supported for reregistration and are therefore not assessed: all pet uses for all
formulations; all indoor uses; all greenhouse uses; all pressurized can formulations; all broadcast
turf uses; and all residential dust formulation uses.
Potential residential and non-occupational uses where exposure may occur include home
gardens (flower and vegetables), home orchards, building perimeters, and back yard foggers.
Additional non-occupational exposure may occur from exposure to wood decks and playground
equipment following aerial ULV sprays for public health mosquito treatment, boll weevil
eradication, and fruit fly treatment. For ease and brevity, the residential use sites have been
grouped as shown in Table 7.
Table 7. Residential Use Sites
Use Site
Homeowner Fruit
Trees
Homeowner
Ornamentals
Homeowner
Vegetables/Small
Fruits
Homeowner
Outdoor Building
Perimeter
Treatments
Outdoor Yard
Target Crops or Pests
Includes apples, cherries,
grapes, peaches, plums,
oranges and tangerines
Includes shade trees,
evergreens, and roses
Includes beans, beets,
broccoli, cabbage, collards,
cucumbers, melons, tomatoes,
peas, peppers and strawberries
Treatment for outdoor
household pests (i.e., roaches,
ants, clover mites, spiders,
silverfish, crickets, earwigs)
Mosquito and flying insect
pests
Maximum Rates
0.034 Ib ai/gallon
0.034 Ib ai/gallon
0.023 Ib ai/gal
0.15471bai/gal
(0.01 lib ai/gal for
hose end sprayer)
0.1 Ib ai/acre
Application Equipment
Low pressure hand wand,
hose end sprayer, and
backpack sprayer.
Low pressure hand wand,
hose end sprayer and
backpack sprayer.
Low pressure hand wand,
hose end sprayer and
backpack sprayer.
Low pressure hand wand,
hose end sprayer, backpack
sprayer.
Handheld fogger
a.
Residential Handler Risks
The Agency determined that exposure to homeowners handling
(mixing/loading/applying) a malathion product is likely to occur via dermal (skin) and inhalation
routes during the residential use of malathion on the use sites shown in Table 7 above. The risk
assessment considered 5 major residential exposure scenarios, based on use patterns and current
labeling, types of equipment, formulations, and techniques that can potentially be used to make
applications of malathion around residential settings. The use patterns assessed are intended to
be representative of the vast majority of the residential uses of malathion. These scenarios
include:
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(la) mixing/loading/applying liquid with a low pressure hand wand;
(Ib) mixing/loading/applying wettable powder with a low pressure hand wand;
(2) loading/applying liquid with a hose-end sprayer;
(3) mixing/loading/applying liquid with a backpack sprayer; and
(4) mixing/loading liquid for fogger.
The Agency considered residential handler exposure scenarios to be short-term (1-30
days), as homeowner applications are not expected to result in continuous exposure duration
greater than 30 days. The residential risk assessment is also based on standard estimates of what
and how much homeowners would typically treat, such as the size of a garden. For more
information on assumptions about the daily volume handled and the area treated used in each
residential handler scenarios, please refer to Malathion: Residential Exposure and Risk
Assessment for the Interim Reregistration Eligibility Decision Document, dated July 6, 2006.
Estimated dermal and inhalation risks for homeowners handling malathion products are
below the Agency's LOG for all handling scenarios. The combined (dermal and inhalation)
MOEs for all scenarios assessed are greater than 100 (ranging from 250 to 13000) based on a
ChE endpoint. All inhalation MOEs based on histopathologic lesions exceed 1000. Although
not tabulated in this document, details on these risk estimates are available in the document
referenced above.
b. Residential Post-Application Risks
The Agency refers to the term "post-application" to describe exposures to individuals that
occur as a result of being in an environment that has been previously treated with a pesticide.
Malathion can be used in areas that can be frequented by the general population including
residential outdoor areas. The Agency has determined that there are potential post-application
exposures to individuals while performing work with treated home vegetable gardens and
fruit/nut trees, and while harvesting strawberries in commercial "pick-your-own" fields. While
the inhalation component of post-application exposure is usually considered to be negligible and,
therefore, not included in most determinations, the potential inhalation exposure following use of
an outdoor fogger is a primary route of exposure and, therefore, has been assessed.
Because of the unique circumstances regarding the special uses of malathion in public
health mosquito abatement control, the USDA's Boll Weevil Eradication Program, and fruit fly
(Medfly) control, potential residential bystander exposure from these uses is assessed in separate
sections later in this document.
Unlike residential handler exposure, where the EPA assumed only adults will be handling
and applying malathion products, individuals of varying ages can potentially be exposed to
malathion when reentering or performing activities in areas that have been previously treated.
The exposure pathway, residential population, and use patterns that were considered in the risk
assessment include:
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• Dermal exposure from residues on vegetable/small fruit gardens (adult);
• Dermal exposure from residues on fruit trees (adult);
• Dermal exposure from "pick your own" strawberries (adult);
• Dermal and inhalation (adults and toddlers) and incidental oral (toddlers only) exposure
following handheld fogger use at residential, park and school settings.
Post-application exposure following building perimeter treatment is considered to be
negligible, and was not assessed. However, existing label language (e.g., EPA Reg. 239-739) for
outdoor household pest control gives a range of directions for perimeter house applications
which includes directions for application to building foundations and wood piles, and application
to the ground surrounding the perimeter of the house in a swath up to 10 feet wide.
EPA considers application of a 10-foot wide swath around most residential structures to
be equivalent to a broadcast turf treatment, a use for which the technical registrant has requested
voluntary cancellation (letter dated July 25, 2006). In addition, data indicates that application of
malathion at the rate intended for residential pest control (0.1547 Ib ai/gallon) may be phytotoxic
to some ornamental species. Therefore, final label directions for perimeter house treatment will
be required which permit application only to structural foundations and to wood piles, and the 2-
foot wide path surrounding them.
For all post-application scenarios listed above, estimated dermal and inhalation risks from
post-application exposure to malathion are below the Agency's LOG (MOEs ranged from 270 -
7800 for adults and 4000 for toddlers) at the residential setting and, therefore, are not tabulated in
this document. A full discussion of assumptions and estimates of residential post-application
exposure is available mMalathion: Residential Exposure and Risk Assessment for the Interim
Reregistration Eligibility Decision Document, dated July 6, 2006.
Residential Post-Application Co-Exposure
The Agency also combines risk values from separate handler and post-application
exposure scenarios when it is likely that they can occur simultaneously, and the toxicity endpoint
is the same. Simultaneous exposure may refer to scenarios where the same individual handles
(mixes/loads) malathion, treats a residential site, and performs post-application activities at that
site on the same day. Table 8 below presents combined residential handler and post-application
risks based on several malathion use patterns.
Table 8. Combined Handling and Post-Api
Scenario
Mixing, loading and applying wettable powder
Dlication Risks from Residential Malathion Uses (Adults)
Total
Dermal
Daily Dose
(mg/kg/day)
0.47
Total
Dermal
MOE1
270
Total Inhal.
Daily Dose
(mg/kg/day)
0.0014
Total
Inhal.
MOE1
18,000
Total
Combined
MOE2
260
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Scenario
with low-pressure handwand on vegetable gardens
plus post-application activities with home fruit
trees.
Mixing, loading and applying wettable powder
with low-pressure handwand on vegetable gardens
plus post-application activities with vegetable
gardens.
Mixing, loading and applying liquids with low-
pressure handwand on fruit trees plus post-
application activities with home fruit trees.
Mixing, loading and applying liquids with low-
pressure handwand on vegetable gardens plus post-
application activities with fruit trees.
Mixing, loading and applying liquids with low-
pressure handwand on fruit trees plus post-
application activities with vegetable gardens.
Total
Dermal
(mg/kg/day)
0.37
0.29
0.24
0.19
Total
Dermal
MOE1
340
440
530
670
Total Inhal.
Daily Dose
(mg/kg/day)
0.0014
0.00001
0.00001
0.00001
Total
Inhal.
MOE1
18,000
2,600,000
2,600,000
2,600,000
Total
Combined
MOE2
330
440
530
670
~ Total MOE = NOAEL/Total Daily Dose, where:
BMDL = 127 mg/kg/day, for dermal, with an LOG of 100 (cholinesterase effects)
NOAEL = 25.8 mg/kg/day, for inhalation, with an LOG of 100 (cholinesterase effects)
2 Total Combined MOE = l/[(l/MOEdermal) + (1/MOEinhalation)]
The total combined MOEs for all assessed residential handler and post-application
scenarios assumed to potentially occur the same day are all greater than 100 and, therefore, do
not exceed the Agency's LOG.
c. Residential Bystander Assessment
The Agency has determined that there is potential for post-application exposures to adults
and children contacting residues of malathion on turf resulting from wide area ULV applications
(public health mosquito control, USDA's Boll Weevil Eradication Program, and fruit fly uses).
Inhalation exposure usually does not factor significantly into post-application risk for home and
garden uses. However, due to the use of malathion in ULV aerial and truck fogger applications
to control mosquitoes (adulticide), its wide use in USDA's Boll Weevil Eradication Program,
and fruit fly (Medfly) control, potential risk from the inhalation route of exposure has been
assessed for both the aerial ULV and ground-based applications. In addition, potential dermal
and non-dietary oral (hand-to-mouth) exposures have been estimated because of the concern for
the residues that may be deposited during the ultra low volume (ULV) aerial and ground-based
fogger applications in the vicinity of residential dwellings and other recreational areas (e.g.,
school playgrounds, parks, athletic fields). The dermal, inhalation, and hand-to-mouth
components of post-application exposure to adults and toddlers have been included for public
health mosquito control, boll weevil eradication, and fruit fly (Medfly) uses.
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For a more detailed review of the assumptions and underlying data used to assess the
residential bystander exposures and risks from these uses see the Malathion: Residential
Exposure and Risk Assessment for the Interim Reregistration Eligibility Decision (RED)
Document, dated July 6, 2006.
Public Health Mosquito Control - Malathion
EPA has determined that there are potential post-application exposures to adults and
children from the ULV aerial and ground-based fogger applications for public health mosquito
control uses in the vicinity of residential dwellings. The assessment was developed to ensure
that the potential exposures are not underestimated, and to represent a conservative model that
encompasses potential exposures received in recreational settings, such as schools, playgrounds,
parks, or athletic fields. The scenarios likely to result in post-application exposures are:
• dermal exposure from residues deposited on turf at residential, park, and school sites
(adult and toddler);
• incidental non-dietary ingestion of residues deposited on turf at residential, park, and
school sites from hand-to-mouth transfer (toddler);
• incidental non-dietary ingestion of residues deposited on turf at residential, park, and
school sites from object-to-mouth transfer (toddler);
• incidental ingestion of soil from treated areas (toddler); and
• inhalation exposure (adult and toddler).
Adult combined risks based on RBC ChEI as the endpoint are calculated using the Total
MOE approach where 100 is the target MOE. For toddlers, however, combined risk was
estimated by calculating an aggregate risk index (ARI) because, while oral, dermal and
inhalation endpoint effects are the same (ChEI), they have different associated target MOEs or
levels of concern (i.e., for dermal and inhalation exposure, the LOG = 1000; for incidental oral
exposure, the LOG = 100). Calculated ARIs equal to or greater than 1 are below the Agency's
LOG. Combined inhalation and dermal short-term risk estimates for adults resulted in MOEs
ranging from 22,000 to 74,000. In addition, the combined dermal, inhalation and incidental oral
risk estimates for toddlers from post-application exposure to malathion following public health
mosquito treatment resulted in ARIs ranging from 9-20. Therefore, estimated combined short-
term risks to adults and toddlers, from all routes of exposure to malathion following both ground
and aerial malathion public health mosquito control treatments, do not exceed the Agency's
LOG. Additionally, inhalation risks based on histopathological lesions exceeded the Agency's
target MOE of 1000 for all scenarios for adults and toddlers (23,000 to 500,000).
Boll Weevil Eradication Program - Malathion
The Boll Weevil Eradication Program (BWEP) is a special project under the direction of
the United States Department of Agriculture designed to systematically eradicate the boll weevil
pest in cotton-growing regions of the US. The Agency has determined that there is potential for
non-occupational post-application exposure to malathion residues from spray drift associated
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with the use of malathion in the BWEP. Potential exposure may result from off target drift
resulting from aerial applications in the vicinity of residential dwellings. The assessment has
been developed to ensure that the potential exposures are not underestimated and to represent a
conservative model that encompasses potential exposures received in residential and other
recreational settings such as schools, playgrounds, parks, and athletic fields.
The Agency's assessment of the BWEP considers the potential for inhalation exposure
(adults and children), dermal contact with residues (adults and children), and incidental ingestion
(children only) of residues deposited on turf and soil. The Agency believes it is reasonable to
expect that the BWEP application scenario may result in dermal, inhalation, and incidental oral
exposure to a single individual within a single day.
The scenarios likely to result in dermal and inhalation (adult and child), and incidental
ingestion (child) post-application exposures resulting from boll weevil control uses are as
follows:
• dermal exposure from residues deposited on turf at residential, park, and school sites
(adult and toddler);
• incidental non-dietary ingestion of residues deposited on turf at residential, park, and
school sites from hand-to-mouth transfer (toddler);
• incidental non-dietary ingestion of residues deposited on turf at residential, park, and
school sites from object-to-mouth transfer (toddler);
• incidental non-dietary ingestion of residues deposited on soil at residential, park, and
school sites from treated areas (toddler);
• inhalation (adult and toddler); and
• inhalation exposure from airborne spray drift (adult and toddler).
Combined risk based on RBC ChEI endpoint for adults were estimated using the Total
MOE approach, while combined risk for toddlers used the ARI methodology previously
described. Combined adult dermal and inhalation exposures from malathion only result in a risk
(total MOE = 3000) that does not exceed the LOG. Likewise, combined toddler exposures from
malathion only result in a risk (total ARI = 1.3) that does not exceed the LOG for post-
application residential (bystander) exposure in areas nearby fields being treated for boll weevil.
Inhalation risks based on histopathological lesions exceeded the Agency's target MOE of 1000
for all scenarios for adults and toddlers (20,000 to 99,000)
Fruit Fly (Medfly) Eradication Treatment - Malathion
Various fruit fly species exist, which when found in areas of fruit and vegetable
production trigger eradication efforts because of the potential economic damage they can inflict.
Malathion, mixed with a protein-hydrolase bait which attracts the flies and applied by air or
ground equipment as a ULV, has been used as part of the fruit fly eradication efforts. Treatment
programs to control fruit fly pests have been undertaken in California, Florida and Texas.
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As with the ULV uses of malathion for public health mosquito control and the BWEP,
fruit fly treatments lead to a potential for non-occupational (residential bystander) post-
application exposures. Potential exposures occur as a result from (i) direct deposition to
residential areas when applications are made in residential areas; and, (ii) from off target drift in
residential areas from applications made to nearby agricultural fields and orchards. The
assessment has been developed to ensure that potential exposures are not underestimated and to
represent a conservative model that encompasses potential exposures received in residential and
public places (e.g., school playgrounds, parks, athletic fields).
This assessment considers the potential for inhalation (adults and children), dermal
contact with residues on residential turf (adults and children), and incidental ingestion (children
only) of malathion residues on residential turf and soil, following application of malathion to
control fruit flies. The Agency believes it is reasonable to expect that the fruit fly application
scenario may result in dermal, inhalation, and incidental oral exposure to a single individual
within a single day.
The scenarios likely to result in dermal and inhalation (adult and child), and incidental
non-dietary ingestion (child) exposures resulting from fruit fly control uses are as follows:
• dermal exposure from residues deposited on turf at residential, park, and school sites
(adult and toddler);
• incidental non-dietary ingestion of residues deposited on turf at residential, park, and
school sites from hand-to-mouth transfer (toddler);
• incidental non-dietary ingestion of residues deposited on turf at residential, park, and
school sites from object-to-mouth transfer (toddler);
• incidental non-dietary ingestion of residues deposited on soil at residential, park, and
school sites from treated areas (toddler); and
• inhalation exposure from airborne spray drift (adult and toddler).
Combined risk for adults based on RBC ChEI endpoint were estimated using the Total
MOE approach, while combined risk for toddlers is expressed using the ARI methodology
previously described. The Agency expects potential exposures and risks associated with aerial
application to be greater than those associated with ground application. Therefore, the Agency
did not assess ground application of fruit fly treatments with malathion. Based on the most
conservative exposure estimates drawn from monitoring data, combined adult dermal and
inhalation exposures following aerial fruit fly treatment result in a risk (total MOE = 5500) that
does not exceed the LOG. Likewise, combined exposure to toddlers from dermal, inhalation, and
incidental oral routes result in a risk (total ARI = 1.7) that does not exceed the LOG. Inhalation
risks based on histopathological lesions exceeded the Agency's target MOE of 1000 for all
scenarios for adults and toddlers (4.5 x 107 to 1.7 x 108)
Combined Residues of Malathion and Malaoxon
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In vivo, malaoxon is the active ChEI, of malathion. Under certain conditions, malaoxon
is formed as an environmental breakdown product of malathion and is available for direct human
exposure. Monitoring data gathered following aerial application of malathion data indicated
malaoxon presence in air, soil, sand and hard surfaces, but minimal to no presence on foliage.
These data further indicated that the greatest potential for malaoxon formation occurs when
malathion residues deposit on hard, dry (anthropogenic) surfaces such as pavement, metal or
wood. For these reasons, the Agency believes that residential contact with outdoor hard surfaces
following aerial application of malathion presents the most relevant and worst case scenario for
assessing the risk from potential malaoxon exposure.
The Agency has estimated toddler exposures from potential contact with malaoxon
residues on wood decks and playground equipment following wide area applications of (ULV)
malathion. The full risk from these scenarios must include not only potential malaoxon
exposure, but also the exposure to the residues of malathion that remain untransformed (to
malaoxon). Therefore, the Agency estimated potential risks to toddlers from the combined
exposure to malathion and malaoxon. Because toddler risks from this scenario are believed to
represent the worst case for all residential populations engaged in any activity on outdoor hard
surfaces, adult exposures and risks were not assessed.
Only limited data exists on the rate of transformation from malathion to malaoxon on
hard surfaces. The data which the Agency does have indicates a range of potential
transformation rates (1%, 5% or 10%), and the Agency has decided to estimate the risk using the
full range. Data on the transformation of malathion to malaoxon will be required as part of the
RED. Further, the Agency received information on the dissipation and breakdown of malathion
to malaoxon, such that when 5% malaoxon is formed, only 40% of untransformed malathion is
present, as opposed to 95% untransformed malathion.
To account for and assess the greater toxicity of malaoxon in residential bystander
settings, the Agency applied the TAP (61x) to estimated residues of malaoxon and combined this
estimated dose with the estimated dose of malathion. Because both chemicals present the same
toxic effect (i.e., cholinesterase inhibition), exposure to both malaoxon and untransformed
malathion residues can be directly added together.
Post-application exposures of toddlers to malathion/malaoxon residues on hard surfaces
following public health mosquitocide, boll weevil eradication treatment, and fruit fly treatment
have been calculated and the details of these can be found in the Malathion: Residential
Exposure and Risk Assessment for the Interim Reregistration Eligibility Decision (RED)
Document, dated July 31, 2006. The calculated exposures in this assessment are not considered
to underestimate risk because they include conservative assumptions, maximum application rates
and conservative deposition estimates.
Risks from individual routes of exposure (dermal and incidental oral) are combined using
an aggregate risk index (ART) and are presented in Table 9 below. The ARI approach is used
30
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because, while dermal and incidental oral toxicity endpoint effects are the same, they occur at
different dose levels and have different associated levels of concern (i.e., for dermal, the LOG =
1000; for incidental oral, the LOG = 100). Calculated ARIs of greater than or equal to 1 are not
of concern to the Agency.
Table 9. Aggregate Risk Index (ARI) for Residential Toddler Bystanders from Combined Residues
of Malathion and Malaoxon
Use Pattern
Public Health, adulticide
Fruit Fly Treatment
Boll Weevil Eradication
Program
Appl.
Method
Aerial
Ground
Aerial
Aerial at 1.2
Ibai/A
Aerial at 0.9
Ibai/A
ARIs Based on Malathion-to-Malaoxon
Transformation Rates
1% Rate
20
340
12
2.6
3.6
5% Rate
12
150
9
1.2
1.6
10% Rate
6
90
5
0.8
1.0
5. Aggregate Risk Assessment for Malathion
The FQPA amends the FFDCA (FFDCA, Section 408(b)(2)(A)(ii)) to require "that there
is a reasonable certainty that no harm will result from aggregate exposure to the pesticide
chemical residue, including all anticipated dietary exposures and other exposures for which there
is reliable information." Aggregate exposure will typically include exposures from food,
drinking water, residential uses of a pesticide, and other non-occupational sources of exposure.
For malathion, EPA conducted a highly refined aggregate risk assessment that combines
exposures across all pathways including food, drinking water, and residential exposure, where
appropriate, resulting from agricultural and non-agricultural uses of malathion. When
aggregating risk from various sources, the Agency considers both the route and duration of
exposure. For malathion, aggregate risk assessments were conducted for acute, chronic and
short-term exposures. The Agency's aggregate assessment accounts for exposure to both
malathion and the oxygen analogue, malaoxon. Results of the aggregate assessment are
summarized here, and are discussed more extensively in the Malathion: Revised Human Health
Risk Assessment for the Reregistration Eligibility Decision Document (RED), dated July 31, 2006
a. Acute Aggregate Risk
The acute aggregate risk assessment for malathion considers exposures from food and
drinking water only, as there are no other pathways of acute exposure. Dietary estimates to all
population subgroups were based on a highly refined (probabilistic) assessment using DEEM
software. Drinking water exposure was assessed using the full distribution of estimated residues
-------
in surface water generated by the PRZM-EXAMS model. All estimated malathion residues in
drinking water were converted to malaoxon residues, multiplied by the TAP (61x), and
combined with the estimated food residues. Total dietary exposure from food and drinking water
was then compared to the aPAD for malathion.
Acute aggregate risk estimates, based on various default input parameters and maximum
registered use patterns (rates and number of applications) from food and drinking water were
above the Agency's LOC (>100% aPAD) at the 99.9- percentile of exposure. The CA lettuce
maximum aerial scenario resulted in the highest drinking water concentration estimates, and
consequently the highest dietary (food + drinking water) exposure estimates. Acute aggregate
(food and drinking water) exposure to malathion, based on the CA lettuce scenario at the
maximum aerial application rate, at the 99.9— percentile was estimated at 144% of the aPAD for
the U.S. population and 520% of the aPAD for all infants (<1 yr old), the most highly exposed
population subgroup.
Based on exposure estimates using refined input parameters (e.g., regional PCAs and 1-
day half-lives) and mitigated use patterns, all acute aggregate (food + drinking water) risk
estimates are below the Agency's LOC (< 100% of the aPAD) for all population subgroups
including all infants. Because total dietary exposure from malathion/malaoxon is less than 100%
aPAD, acute aggregate exposure from malathion is below the Agency's LOC. Table 10 below
summarizes those acute aggregate (food + drinking water) risk estimates for malathion which
were refined; other acute aggregate (food + drinking water) risk estimates for malathion which
were below the Agency's LOC when default inputs were used, are not presented.
Table 10. Selected1 Acute Aggregate Exposure and Risk Estimates (Food and Drinking Water)
Site
Population
% aPAD
(Default Inputs
and Maximum
Use Patterns)
% aPAD
(Refined Inputs
and Mitigated
Use Patterns)
Comments
Acute Aggregate Dietary Estimate at the 99.9th Percentile
Lettuce, CA
U.S Population
All Infants (< 1 yr)
Children 1-2 yrs
Children 3 -5 yrs
144
520
218
200
19
63
29
27
Default estimates were refined with:
- proposed application values
- regional PCA
- 1 day half-life
Peach, TX
U.S Population
All Infants (< 1 yr)
Children 1-2 yrs
Children 3 -5 yrs
146
485
222
201
22
73
34
30
Used GA Peach as surrogate model
Default estimate was refined with:
- proposed application values
- regional PCA1
Citrus, FL
U.S Population
All Infants (< 1 yr)
Children 1-2 yrs
123
430
184
11
37
20
Default estimate was refined with:
- proposed application values
32
-------
Site
Population
% aPAD
(Default Inputs
and Maximum
Use Patterns)
% aPAD
(Refined Inputs
and Mitigated
Use Patterns)
Comments
Acute Aggregate Dietary Estimate at the 99.9th Percentile
Tomato, FL
Children 3 -5 yrs
U.S Population
All Infants (< 1 yr)
Children 1-2 yrs
Children 3 -5 yrs
166
115
410
177
162
17
-
72
-
-
Default exposure estimates refined
with:
- proposed revised application rates
- regional PCA
All population subgroups have lower
estimated exposure than all infants,
therefore other populations were not
modeled
Strawberry, CA
U.S Population
All Infants (< 1 yr)
Children 1-2 yrs
Children 3-5 yrs
102
370
153
140
20
59
30
28
Default estimate was refined with:
- first application date
- regional PCA
This scenario was also run with the
more conservative 3 day half -life,
which resulted in aPAD for all
children of 99%.
Cotton, MS
U.S Population
All Infants (< 1 yr)
Children 1-2 yrs
Children 3 -5 yrs
73
262
111
101
7
19
13
11
Default estimates refined with
- proposed revised application rates
Cherry, WA
U.S Population
All Infants (< 1 yr)
Children 1-2 yrs
Children 3 -5 yrs
62
207
91
81
29
94
43
39
Default estimate was refined with:
- proposed application values
- regional PCA
- 1 day soil half -life
Cabbage, FL
U.S Population
All Infants (< 1 yr)
Children 1-2 yrs
Children 3 -5 yrs
57
195
83
76
13
46
22
20
Default estimates refined with:
- proposed revised application rates
Sorghum, TX
U.S Population
All Infants (< 1 yr)
Children 1-2 yrs
Children 3-5 yrs
39
128
58
53
5
12
9
9
Default estimates refined with:
- proposed revised application rates
Asparagus, WA
U.S Population
All Infants
(< i yr)
Children 1-2 yrs
38
123
55
-
94
-
Default estimate was refined with:
- proposed application values
- regional PCA
All population subgroups have lower
estimated exposure than all infants
33
-------
Site
Population
% aPAD
(Default Inputs
and Maximum
Use Patterns)
% aPAD
(Refined Inputs
and Mitigated
Use Patterns)
Comments
Acute Aggregate Dietary Estimate at the 99.9th Percentile
Children 3-5 yrs
51
-
(<1), therefore, other populations
were not modeled
1: EPA modeled 16 crop scenarios to assess drinking water exposure. Only those which exceeded the Agency's
LOG when default input parameters were used are shown here, and refinements implemented.
2: An adequate Peach, TX modeling scenario was unavailable; therefore, EPA combined south central PC A with GA
peach modeling scenario.
b. Chronic Aggregate Risk
The chronic aggregate exposure to malathion from food and drinking water is below the
Agency's LOG for the U.S. general population and all population subgroups. For all drinking
water scenarios assessed, including the worst-case aerial CA lettuce scenario with maximum
application rates, all chronic aggregate dietary exposure from food and drinking water for the
U.S. population and all infants <1 yr, the most highly exposed population subgroup, was <1% of
the cPAD. Table 11 provides a summary of chronic aggregate exposure estimates and risk
estimates for food and drinking water.
Table 11. Chronic Aggregate Dietary Exposure and Risk (Food + Drinking Water)
Population Subgroup
General U.S Population
All Infants < 1 year old
Children 1-2 years old
Children 3-5 years old
cPAD
(mg/kg/day)
0.07
0.07
0.07
0.07
Exposure
(mg/kg/day)
0.000224
0.000469
0.000456
0.000441
Percent of the
cPAD
< 1
<1
<1
<1
c. Short-Term Aggregate Risk
Aggregate short-term (1-30 days) risk estimates include the contribution from chronic
(average) dietary sources (food + drinking water) and short-term residential sources. Several
short-term residential exposure scenarios exist that could be aggregated with the chronic dietary
exposure sources. Short-term residential exposure (dermal + inhalation + incidental oral)
scenarios include adult residential handler, adult and toddler bystander exposure to the home and
garden uses of malathion, and toddler bystander exposure to the wide area uses of malathion
(BWEP, public health, and Medfly control). Since the estimated exposures resulting from the
wide area use assessments incorporate potential exposure to malaoxon, they are more
conservative than the estimated exposures resulting from the residential uses and, therefore, have
been chosen for the aggregate assessment. Among the wide area uses of malathion, the Agency
believes that aerial application of public health use of malathion represents the most likely, and
34
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wide spread co-occurring exposure pathway for the general U.S. population. To be conservative,
the Agency assessed this scenario at the 10% conversion rate of malathion to malaoxon.
Short-term bystander exposure from public health use considered incidental oral (hand to
mouth), and dermal exposure to both malathion and malaoxon. MOEs for incidental oral
exposure are 1,900, and for dermal are 9,100. Chronic aggregate dietary exposures for all infants
(< 1 yr old), the most highly exposed population subgroup, is < 1% of the cPAD. The Agency
combined these risks using the Aggregate Risk Index (ARI) method, since the target LOG for
oral exposure (hand to mouth, and dietary) differs from that of dermal exposure. When using the
ARI method, the Agency considers risks equal to or greater than 1 to be not of concern. As
presented in Table 12, when chronic dietary (food + drinking water) is added to the oral and
dermal exposure components, the total aggregate ARI is 6 and, therefore, below the Agency's
LOG.
While the Agency believes that the public health use of malathion is the most appropriate
scenario for short-term aggregate risk characterization, it is not the most conservative; rather
toddler bystander exposure from the BWEP represents the most conservative residential
exposure scenario. There are several reasons why EPA believes that the BWEP scenario is not
the most appropriate co-exposure scenario for aggregation. First, the BWEP is a time limited
program. The USD A Animal and Plant Health Inspection Service (APHIS) has projected that
the eradication phase of the program will end by 2009. Thereafter, USD A/APHIS intends to
control the boll weevil by applying malathion only where outbreaks occur, which will result in a
significant reduction of malathion applied and, therefore, a significant reduction of potential
exposure. The BWEP is also very targeted, being managed and administered in only those states
and counties currently active in the eradication phase of the program. As of March 2006,
USD A/APHIS reports that boll weevil has already been successfully eradicated in 10 states with
active eradication efforts currently underway in 7 states and Mexico. In contrast, the public
health use of malathion is national (on a yearly basis) and is broadcast over wider areas
(including residential), not just to agricultural fields as malathion is used in the BWEP. Finally,
the BWEP has a community outreach and notification component which helps reduce potential
exposure from off target drift to bystanders. For these reasons, EPA believes that the BWEP is a
less appropriate scenario for aggregation, than the public health use of malathion. Nonetheless,
the Agency aggregated this use with the chronic dietary exposure as a worst-case scenario.
When estimating risk from the BWEP, the Agency considered both the maximum application
rate as well as the typical application rate. Based on information provided by USD A/APHIS
which indicates that the predominantly used typical rate in the BWEP is 0.9 Ib ai/A (greater than
99% of the acreage is treated at this rate or below), the Agency assessed the predominantly used
typical rate (0.9 Ib ai/A) for aggregate short-term risk as well as the maximum rate (1.2 Ib ai/A).
At the maximum application rate, and at the maximum 10% malaoxon conversion rate the
estimated aggregate risk, combining the bystander BWEP scenario with chronic dietary (food +
drinking water), results in an ARI of 0.8 and, therefore, above the Agency's level of concern.
However, based on the predominantly used typical rate of 0.9 Ib ai/A, and at the maximum 10%
malaoxon conversion rate, the estimated ARI is 1 and, therefore, below the Agency's LOG.
35
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Table 12 summarizes short-term aggregate risk to children 1-2 years of age for public health
mosquitocide and BWEP.
Table 12. Short-term Aggregate Risk to Children 1-2 Years
Use Scenario
Public Health Mosquito Control
(10% malaoxon conversion)
BWEP at Max App. Rate (1.2 Ib ai/A)
(10% malaoxon conversion)
BWEP at Typ App Rate (0.9 Ib ai/A)
(10% malaoxon conversion)
ARI
Food +
Water1
160
160
160
ARI
Oral1
19
3.6
3.6
ARI
Dermal1
9.1
1.4
1.6
Aggregate ARI2
6.0
0.8
1.0
1 ARI = [MOEcALcuLAiED * MOEACCEPTABLE] (Note: Target ARI = 1)
2 Aggregate ARI = 1
1
+ 1
ARI
-FOOD + WATER
ARI
1
-ORAL
ARI
-DERMAL
d. Malathion Pesticide and Pharmaceutical Use Co-
Exposure Assessment
As indicated above, in determining the risk to human health, the Agency examines more
than just dietary exposures. Section 408 of FFDCA requires EPA to consider potential sources
of exposure to a pesticide and related substances in addition to the dietary sources expected to
result from a pesticide use subject to the tolerance. In order to determine whether to maintain a
pesticide tolerance, EPA must "determine that there is a reasonable certainty of no harm. . . ."
Under FFDCA section 505, the Food and Drug Administration reviews human drugs for safety
and effectiveness and may approve a drug notwithstanding the possibility that some patients may
experience adverse side effects. EPA does not believe that, for purposes of the section 408
dietary risk assessment, it is compelled to treat a pharmaceutical patient the same as a non-
patient, or to assume that combined exposures to pesticide and pharmaceutical residues that lead
to a physiological effect in the patient constitutes "harm" under the meaning of section 408 of the
FFDCA.
Rather, EPA believes the appropriate way to consider the pharmaceutical use of
malathion in its risk assessment is to examine the impact that the additional non-occupational
pesticide exposures would have to a pharmaceutical patient exposed to a related (or, in some
cases, the same) compound. Where the additional pesticide exposure has no more than a
minimal impact on the pharmaceutical patient, EPA could make a reasonable certainty of no
harm finding for the pesticide tolerances of that compound under section 408 of the FFDCA. If
the potential impact on the pharmaceutical user as a result of co-exposure from pesticide use is
more than minimal, then EPA would not be able to conclude that pesticide residues were safe
and would need to discuss with FDA appropriate measures to reduce exposure from one or both
sources. The Agency provided its preliminary findings with respect to malathion to FDA in a
36
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letter dated August 10, 2005, which is available on the public docket (EPA-HQ-OPP-2004-
0348).
The exposure estimates used in the determination of malathion pharmaceutical and
pesticide co-exposure assessment, Attachments 1 and 2 to the July 25, 2005 letter, referenced
above, reflects the external dermal dose of malathion a patient treated with a pharmaceutical
malathion product would receive in a reasonable worst-case scenario. EPA's pesticide exposure
assessment has taken into consideration the appropriate population, exposure route, and exposure
duration for comparison with exposure to the pharmaceutical use of malathion. Using the
malathion (Ovide® Lotion 0.05%) registered pharmaceutical label, EPA estimated exposure
from a typical treatment of that product, and compared that to the potential exposure an
individual would receive from the pesticide uses of malathion. Because the Ovide® Lotion is
indicated for use over an 8 - 12 hour period, EPA considers the pharmaceutical use as a short-
term exposure. To estimate combined pesticide exposure for a short-term scenario, EPA
integrated average dietary exposure estimates (food + drinking water) with one of the non-
occupational exposure scenarios (i.e. post-application to malathion residues from wide area
public health applications). EPA chose the wide area public health exposure scenario because
this application is a reasonable high-end scenario, and is likely to result in a large number of
individuals potentially exposed to malathion pesticide residues.
In connection to its Revised Malathion Human Health Risk Assessment, issued
September 2005, EPA worked with FDA to determine whether the additional malathion
exposure from the pesticide uses would pose a safety concern to a patient using Ovide® Lotion.
In a letter dated August 26, 2005, FDA stated that based on EPA calculations of potential high-
end pesticide exposure (0.27 mg/kg/day), such exposure in patients receiving Ovide® Lotion
treatment would fall within the expected upper range of exposure following Ovide® Lotion use
alone, and would not present an increased safety risk.
As discussed above, comments were received in connection with the issuance of the
Revised Malathion Human Health Risk Assessment that has resulted in a recalculation of the
average dietary exposure and non-occupational exposure (wide area public health use) estimates.
The recalculated combined pesticide exposure is within the dose range considered by FDA in its
August 26, 2005 letter and below the high-end pesticide exposure estimate that FDA concluded
would not increase risk beyond the range expected for the pharmaceutical use alone. Therefore,
because the pesticide exposure has no more than a minimal impact on the pharmaceutical patient,
the Agency believes that there is a reasonable certainty that the potential pesticide exposure will
result in no harm to a patient also receiving Ovide® Lotion.
6. Occupational Exposure and Risk
Workers can be exposed to a pesticide through mixing, loading, and/or applying the
pesticide, or re-entering a treated site. The Agency assessed risk to occupational handlers and
workers in the same fashion as it used to assess risks to residential bystanders, i.e., by using the
37
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Margin of Exposure (MOE) approach. The MOE reflects how close an occupational exposure
comes to the No Observed Adverse Effect Level (NOAEL) or some other PoD, the dose
considered to result in no adverse health effects. The Agency is not concerned if the estimated
exposure is lOOx less than the PoD (the difference equal to the UF which accounts for the intra-
species and inter-species variation). Please see Table 2 for the summary of toxicological
endpoints used in this assessment. Both short- and intermediate-term exposures are expected to
occur to handlers from registered malathion use patterns. The risk assessment for short-term (1-
30 days) and intermediate-term (1-6 months) occupational exposures are similar because the
toxicity endpoints, the PODs and the target MOE, are the same for both durations. Chronic
exposure (> 6 months) is not expected for handlers and, therefore, is not assessed. Even though
the Agency selected separate endpoints for dermal exposure versus inhalation exposures (ChEI
as the toxicity endpoint for dermal exposure and histopathologic lesions as the toxicity endpoint
for inhalation exposure), the contribution of inhalation exposure to the ChE endpoint was also
considered. Therefore, in calculating the short- and intermediate-term risks for ChEI, total
MOEs were estimated for combined dermal and inhalation exposures, as well as MOEs for
inhalation only to address risk from histopathological lesions.
For malathion, total MOEs that are greater than 100 generally do not exceed the
Agency's LOG. However, when occupational MOEs are less than 100, EPA strives to reduce
worker cancer risks through the use of personal protective equipment, engineering controls, or
Restricted-Entry Intervals (REIs). MOEs for inhalation (histopathological lesions) greater than
1000 do not exceed the Agency's LOG.
a. Occupational Handler Exposure and Risk
Exposure to malathion by pesticide handlers (mixers, loaders, applicators and flaggers) is
likely during the use of malathion based on the type of equipment and techniques that can
potentially be used. Twenty-six occupational exposure scenarios were assessed based on
registered labels, equipment, and techniques that could be used for malathion applicators. Due to
the scope of the various malathion occupational uses (there are over 200 registered malathion
products), it would be difficult to assess each individual exposure scenario. Therefore, the
following selected scenarios are representative of the worse-case exposure scenarios to represent
the major ways malathion can be handled in the occupational environment. The scenario
numbers correspond to the non-cancer risk estimate tables presented in the Malathion:
Occupational Exposure and Risk Assessment for the Interim Reregistration Eligibility Decision
(IRED) Document, dated July 6, 2006.
The labeled use patterns indicate a number of exposure scenarios based on the types of
equipment and activities used to make malathion applications. These scenarios include:
1) mixing/loading liquids for chemigation application;
2) mixing/loading liquids for groundboom application;
3) mixing/loading liquids for aerial application;
38
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4) mixing/loading liquids for airblast sprayer;
5) mixing/loading liquids for dipping;
6) mixing/loading liquids for a fogger;
7) mixing/loading liquids for handgun sprayer;
8) mixing/loading liquids for truck mounted ULV sprays;
9) applying liquids via groundboom;
10) applying liquids via airblast;
11) applying liquids via aerial;
12) applying liquids via handgun sprayer;
13) applying liquids via truck mounted sprayer;
14) applying liquids via dip;
15) mixing/loading/applying liquids via handgun sprayer;
16) mixing/loading/applying liquids via low pressure handwand;
17) mixing/loading/applying liquids via backpack sprayer;
18) mixing loading/applying liquids via paint brush;
19) mixing/loading/applying liquids via dip;
20) flagging for aerial spray application;
21) mixing/loading wettable powders for aerial;
22) mixing/loading wettable powders for chemigation application;
23) mixing/loading wettable powders for groundboom application;
24) mixing/loading wettable powders for airblast application;
25) loading dusts for power duster; and
26) applying dusts with a power duster.
The level of personal protective equipment (PPE) varies on the numerous malathion
labels. Some labels only require the minimum level of PPE, while others require additional PPE,
such as chemical-resistant gloves, respirators, etc., depending on the labeled handler activity.
Therefore, the Agency considered the following levels of PPE or engineering controls in the
occupational exposure assessments:
• Baseline, or long-sleeved shirt, long pants, no gloves, and no respirator. (Baseline)
• Baseline plus chemical-resistant gloves, and no respirator. (PPE-G-NR)
• Coveralls worn over long-sleeved shirt and long pants, chemical-resistant gloves, and
no respirator. (PPE-G-DL-NR)
• Baseline plus chemical-resistant gloves and an 80% PF (quarter-face dust/mist)
respirator. (PPE-G-80%R)
• Coveralls worn over long-sleeved shirt and long pants, chemical-resistant gloves, and
an 80% PF (quarter-face dust/mist) respirator. (PPE-G-DL-80%R)
• Engineering Controls, or closed mixing/loading system, enclosed cab, or enclosed
cockpit. (EC)
Except for malathion handlers and applicators using closed mixing/loading systems to
support aerial application to cotton and dust application to dates, no chemical-specific handler
39
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exposure data were submitted in support of the reregi strati on of malathion. Therefore, an
exposure assessment for most scenarios was developed, where appropriate data are available,
using the Pesticide Handlers Exposure Database (PHED) Version 1.1. PHED is a generic
database containing measured exposure data for workers involved in the handling or the
application of pesticides in the field (i.e., currently contains data for over 2,000 monitored
exposure events).
For each of the 26 handler scenarios above, the Agency considered numerous crops or
target use sites with various application rates and daily treated area to reflect the way in which
malathion can be applied (approximately 555 various use patterns were assessed). Additionally,
due to the broad spectrum use of malathion, the Agency believes that occupational exposure can
occur over a single day or up to a week's time for many use-patterns, and intermittent exposure
over several weeks are also anticipated. Therefore, the risk assessment considers both short- (1-
30 days) and intermediate-term (1-6 months) exposure to malathion; combining dermal and
inhalation exposures to assess risks from ChEI and evaluating inhalation exposures alone to
assess histopathological lesions.
Handler Risks
The majority of the risk estimates were below the Agency's LOG, with MOEs ranging
from 100 to 490,000 when baseline PPE and chemical-resistant gloves were applied and are,
therefore, not tabulated in this document. However, 17 of the over 500 use patterns assessed
either had no data available for conducting an assessment, or required additional PPE or
engineering controls before the risk estimates were below the Agency's LOG, and are listed in
Table 13. One scenario, however, mixing/loading/applying (M/L/A) liquid concentrates with a
low pressure handwand to overhead/fruit trees, was assessed but no data were available to
estimate MOEs with anything other than baseline clothing, which exceeded the LOG. This
scenario is very similar to another low pressure handwand M/L/A scenario which has data
available to calculate MOEs with baseline PPE and chemical-resistant gloves and which is not of
concern with that level of protection. This scenario effectively serves as a surrogate for the
overhead/tree fruit scenario with no data and is, therefore, not tabulated in Table 13 below.
Table 13. Summary of Malathion Occupational Handler Risk Estimates (MOEs) Requiring PPE
greater than Baseline and Gloves
Exposure Scenario
Crop or Use
Application
Rate
Max.
Area
Treated
Daily
Base-
line
PPE-G-
NR
PPE-G-
80%R
PPE-G-
DL-
80%R
EC
Mixer/Loader (M/L)
MIL Liquids for ULV
Aerial Application
M/L Wettable Powders
for Aerial Application
Field & Row Crop
(Rice, Barely , Oats,
Rye, and Wild Rice)
Field & Row Crops
(Cotton)
Blueberries (Low)
0.611bai/A
1.221bai/A
1.251bai/A
0.76 Ib ai/A
7500 A
7500 A
350 A
350 A
1
0
5
9
67
34
53
88
ND
ND
96
160
110
53
120
NA
NA
110
NA
NA
40
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Exposure Scenario
Crop or Use
Application
Rate
Max.
Area
Treated
Daily
Base-
line
PPE-G-
NR
PPE-G-
80%R
PPE-G-
DL-
80%R
EC
Mixer/Loader (M/L)
M/L Wettable Powder
for Chemigation
Blueberries
(Vine/Trellis)
Blackberry,
Boysenberry,
Dewberry,
Loganberry, and
Raspberry
Blueberries (Low)
Blueberries
(Vine/Trellis)
Strawberries
Blackberry,
Boysenberry,
Dewberry,
Loganberry, and
Raspberry
1.251bai/A
0.76 Ib ai/A
2 Ib ai/A
1.251bai/A
0.76 Ib ai/A
1.251bai/A
0.76 Ib ai/A
2 Ib ai/A
2 Ib ai/A
350 A
350 A
350 A
350 A
350 A
350 A
350 A
350 A
350 A
5
9
3
5
9
5
9
3
3
53
88
33
53
88
53
88
33
33
96
160
60
96
160
96
160
60
60
120
NA
74
120
NA
120
NA
74
74
NA
NA
1,200
NA
NA
NA
NA
1,200
1,200
Application Only
Liquids via Aerial
Application
Dust Via Mechanical
Duster
All 77 crop
scenarios assessed
Tree Fruit:
Evergreens
(Tropical)
0.175 to 8
Lbai/A
4.25 Ib ai/A
2.75 Ib ai/A
350 to
7500 A
5A
5A
NO
NO
NO
NO
NO
NO
NO
NO
NO
NO
NO
NO
180 to
27,000
NO
NO
Mixing/Loading/Applying (M/L/A)
Mixing/Loading/Apply
ing Dip
Grape root
0.019 Ib
ai/gallon
100
gallons
NO
NO
NO
NO
NF
ND= No Data
NF= Not Feasible
NA=Not Assessed
b. Occupational Post-Application Exposure and Risk
EPA uses the term "post-application" to describe exposure to an individual which occurs
as a result of entering into an environment that has been previously treated with a pesticide (also
referred to as reentry exposure). Many crops (or other pesticide treated environments) require
distinct job functions which must occur in an environment, following the application of a
pesticide product. The job requirements, the nature of the environment, or target that was
treated, and how the chemical residues degrade in the environment can cause exposure levels to
differ over time. Each factor has been considered in this assessment in determining the safety of
persons who are subject to post-application pesticide exposure.
41
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In estimating post-application exposure and risk, transfer coefficient data, which is a
measure of the residue transferred from a treated surface to a person who is performing an
activity in a treated area, are used in conjunction with dislodgeable foliar residue (DFR) data.
DFR data is a unique measurement of the amount of pesticide residue on a treated surface which
is available for transfer. DFR data is specific to a compound and describes (by algorithmic
function) the dissipation of that chemical over time. EPA has six separate DFR studies on
malathion. All agricultural occupational post-application scenarios for malathion were evaluated
using one of these six DFR studies.
Occupational post-application exposure (for a given activity/crop combination) is
calculated by multiplying the DFR data by the transfer coefficient(s) for that activity/crop
combination. The calculation takes into account the application rate for each specific crop, and
is normalized by body weight and adjusted for dermal absorption (if necessary). The frequency
and duration of post-application occupational exposure is also considered in EPA's estimates of
post-application exposure and risk. Short-term exposure durations (1730 days) are typically
considered, and intermediate-term exposure durations (1-6 months) are appropriate for exposures
scenarios where the pesticide is reapplied several times over a growing season, or the pesticide
residues persist for relatively long periods of time. For malathion, the exposure durations for
noncancer post-application risk assessment were short-term and intermediate-term. The dermal
toxicological endpoint of concern is the same for both exposure durations, i.e., ChEI. Since
malathion has a very low vapor pressure, inhalation exposures are considered to be negligible in
outdoor post-application scenarios. DFR data multiplied by the appropriate transfer coefficient
yields an estimated dose. The estimated dose is then compared to the selected PoD endpoint (see
Table 2), with a target MOE of 100.
EPA does not consider the use of personal protective equipment (PPE), or other types of
equipment as a viable option to reduce occupational post-application exposures. However, the
Restricted-Entry Interval (REI) is considered an acceptable risk mitigation approach for
occupational post-application scenarios. The REI is the required time period, following a
pesticide application, during which entry into the treated area is prohibited for workers
performing conventional tasks. The Agency sets the REI equal to the time required for the
estimated risk to be above the Agency's LOG (i.e., the REI is set equal to the time required for
the MOE to be equal to or greater than 100). Currently, all malathion labels specify a 12-hour
REI.
For this assessment, the Agency assessed not only the current maximum supported
application rate, but also the proposed revised application rate. Based on a revised dermal
toxicological endpoint of 127 mg/kg/day, and the proposed revised application rates, the vast
majority of occupational post-application scenarios result in MOEs greater than 100 at 12 or 24
hours following application. In several cases a 2-day REI is required to reach the target MOE of
100, and for detasseling corn and tying grapes, a 4-day REI is required. Table 14 provides a
summary of occupational post-application REIs for those use sites that require more than the
42
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current 12 hour REI based on the maximum supported application rate and, where appropriate,
the recalculated REI based on the proposed revised application rate.
Table 14. Summary of Use Sites that Req
Use Site
Cotton
Peanuts
Peas
Corn
(field, seed, sweet and
pop)
Apricots
Nectarine, peach
Figs
Cherries
(sweet and tart)
Grapefruit, Lemon, lime,
orange, tangelo,
tangerine,
Avocado
Kumquat
Dates
Pine seed orchards,
Christmas tree
plantations, slash pine
plantations, forest trees
Chestnuts
Pecans
Walnuts
Forest trees
Application Rate
(Ib ai/A)
2.5
1.22
2.5
2.5
1.0
1.0
0.61
3.75
1.5
3.75
3.0
2.5
2.0
3.75
1.75
6.25
CA: 7.5
Rest of US: 4. 5
4.70
4.7
6.25
4.5
4.25
2.5
5
2.5
2.5
8.0
2.5
2.5
uire More than 12 Hour REI
Application Rate Source
Current
Current
Current
Current
Amended
Amended
Current
Current
Amended
Current
Amended
Current
Amended
Current
Amended
Current
Amended
Amended
Current
Amended
Current
Amended
Current
Current
Current
Amended
Current
Amended
Current
Current
REI
2 days
24hrs
24hrs
2 days
12hrs
4 days for detasseling and
hand harvesting;
12 hrs for all other activities
3 days for detasseling and
hand harvesting;
12 hrs for all other activities
12 hrs for med expos;
2 days for high expos
12 hrs
2 days
24 hrs
24 hrs
24 hrs
2 days
12 hrs
3 days
3 days
2 days
3 days
2 days
3 days
2 days
2 days
24 hrs
2 days
24 hrs
24 hrs
3 days
24 hrs
24 hrs
43
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Use Site
Garden beets, carrot,
horseradish, parsnip,
radish, rutabaga, salsify,
turnip
Chayote root, yams
Garlic, leeks, green
onion, shallots
Chayote fruit, cucumber
Summer squash
Eggplant
Tomato (fresh and
processed), tomatillo
Broccoli, broccoli raab,
Brussels sprouts,
cabbage, cauliflower,
Chinese broccoli
Celery, kohlrabi
Collard, kale, mustard
green, Chinese greens
Dandelion
Parsley
Spinach
Swiss chard
Endive and escarole
Lettuce
Chives
Watercress
Pineapples
Grape
(wine, table, raisin)
Application Rate
(Ib ai/A)
1.25
1.56
1.56
1.88
1.88
1.75
3.43
1.56
3.43
1.56
1.25
1.25
1.25
2
1.25
2
1.5
2
2
1.88
1.24
1.88
1.56
1.25
5
1.88
Application Rate Source
Current
Current
Current
Current
Current
Amended
Current
Amended
Current
Amended
Current
Current
Current
Current
Amended
Current
Amended
Current
Current
Current
Amended
Current
Current
Current
Current
Current
REI
24hrs
24hrs
24hrs
24hrs
24hrs
24hrs
24hrs
12hrs
24hrs
12hrs
2 days
24hrs
24hrs
2 days
24hrs
2 days
24hrs
2 days
2 days
24hrs
12hrs
24hrs
24hrs
24hrs
2 days
3 days for girdling and cane
turning;
12 hrs for all other activities
c. Incident Reports
The number of malathion exposures and poisonings has declined in recent years;
however, most of this decline has occurred in the residential setting and there are no usage
surveys to determine whether all or most of this decline is due to less use or safer handling.
44
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Likely, some of the decline is due to less widespread use of malathion due to Medfly outbreaks
and as a choice for use against carriers of West Nile Virus. Although agricultural use has
declined slightly in California in recent years, it does not explain most of the decline in
poisonings reported from that State.
Symptoms commonly reported for malathion exposure cover the spectrum normally
associated with organophosphate exposure, and include headache, nausea, dizziness, muscle
weakness, drowsiness, difficult breathing, diarrhea, excess secretions, agitation, confusion,
blurred vision and, death from accidental or intentional ingestions (i.e., suicides). The most
recent five years of data (1999-2003) from California show a marked decline of 59% (from 27.5
to 11.2) in total illnesses attributed to malathion from the 1982-1998 time span. There were 79
cases reported from 1999-2003 and, of these, malathion was determined to be the primary cause
of illness in 55 cases. As before, cases were included if malathion was considered a possible,
probable, or definite cause of the reported illness. Only 5 of the 55 cases were related to use in
agriculture and 4 of the 5 were systemic poisonings. On average, there were 14,846
agriculturally-related applications of malathion from 1999 through 2003 in California. Thus,
there were 0.27 systemic poisonings per 1,000 applications from 1999-2003, which compares
favorably with much older data from 1982 through 1989, which found a median of 0.41
poisonings per 1,000 applications. However, the earlier data did not have a requirement that all
agricultural applications be reported, just commercial and applications by a licensed pesticide
applicator. Therefore, it is not clear whether the current rate of poisoning per thousand
applications is due to a real decline or an artifact of use reporting. Still, the decline in systemic
poisonings from 1990-96 (20.4 per year) to 1999-2003 (8.2 per year) demonstrates a 60% decline
in all systemic poisonings, which appears to be not solely a result of the decline in malathion use.
The pattern of incidents was similar to previous years. There were three suicides
(ingestions of concentrate: 6-8 ounces, over a cup, and an unknown quantity) and 3 attempted
suicides (one case ingested about 8 ounces of 0.125% malathion). Also, a number of rescue
personnel attending the suicide victims were also poisoned by the strong odor and from contact
with contamination. There were four such individuals in one case, and nine persons sick from
attending another suicide victim. Fourteen of the cases became sick from applications that
occurred nearby (e.g., from drift). Some of these were due to highly concentrated applications
that had not been diluted properly. Five cases involved the applicators themselves, and in six
cases there was mention of a leaking or broken bottle.
Much of the information presented above has inherent limitations, including inadequate
documentation of exposure and effects, reporting biases and absence of denominator information
on the population at risk. However, certain consistent patterns of risk factors can be identified.
The large majority of malathion incidents appear to involve minor symptoms, which in many
cases may be a reaction to the odor rather than cholinergic poisoning. Nonetheless, symptoms
brought on by odor effects are poisonings by definition. Broken bottles and other inadequate
packaging accounted for over a quarter of the cases in California from 1982 through 1995. Drift
and exposure to odors was another common cause of incidents in California. These latter
45
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incidents typically resulted in mild and transient symptoms. In many cases it appears that
symptoms are brought on by the offensive odor of the compound alone (i.e., ChE depression
need not be present). More serious malathion cases typically involve application by hand or
backpack sprayer and direct exposure to concentrate. Often, serious exposures result from
equipment failure, such as hose breaks or failure to exercise minimal precautions during
maintenance or clean-up. Though less hazardous than other OPs and carbamates on most
measures, malathion has a higher incidence of life-threatening cases in Poison Control Center
data. Extensive exposure to concentrates appears to be a likely risk factor in these cases.
B. Environmental Fate and Effects Assessment
A summary of the EPA's environmental fate and ecological effects of malathion is
presented below. The full assessment, Revised EFED RED Chapter for Malathion (May, 2000)
and response to public comments are available on the internet and in the public docket (EPA-
HQ-OPP-2004-0348). Updates to the risk assessment include the following:
• incorporation of malaoxon fate data (hydrolysis and conversion data);
• refinement to surface water concentration estimates using typical application information,
regional percent cropped area values, and crop specific application information;
• consideration of buffer zones to reduce off target drift from EC/WP formulation and
ULV formulation applications;
• reassessment of off target drift resulting from the Boll Weevil Eradication Program; and
• revision to the public health use parameters based on the provision of the PR Notice
2005-1 for Public Health Use Pesticides.
1. Environmental Fate and Transport
The primary routes of dissipation of malathion in surface soils appear to be microbially
mediated soil metabolism and hydrolysis. Malathion is generally nonpersistent; but open
literature studies suggest that its persistence is longer on soil that is of dry, sandy, low nitrogen,
low carbon, and acidic quality. Aerobic soil metabolism data indicate that half-life values for
malathion range from several hours to nearly 11 days. The persistence of malathion is decreased
with microbial activity, moisture, and high pH. While malathion exhibits short soil persistence,
which reduces the likelihood it will leach to groundwater, its low Kd value, and data from
various leaching studies, and groundwater detections in three states (CA, MS, and VA) indicate
that malathion does have potential to leach to groundwater. Other important routes of dissipation
from soil, suggested by the data, include leaching, plant uptake, and surface runoff.
In general, malathion and its degradates are soluble and do not adsorb strongly to soils,
and, therefore, are likely to be mobile. Guideline studies and open literature show that malathion
is unstable under alkaline conditions and increasingly stable under acidic conditions. While
malathion is stable under sunlight, it photodegrades slowly in natural and distilled water
(reported half lives ranging from 0.67 to 42 days). Open literature in conjunction with registrant
46
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submitted studies suggest that malathion is unlikely to persist in anaerobic aquatic conditions.
Aerobic aquatic metabolism data indicate that malathion's half-life can vary from 1 day to two
weeks. Malathion has a relative low vapor pressure, indicating that gas phase reactions are only
minor routes of degradation
EPA has limited data on malaoxon, the oxon analogue, and the other
impurities/degradates of malathion. However, based upon the chemical similarity between
malathion and malaoxon, it is expected that malaoxon will have similar fate properties as its
parent. As discussed earlier in this document, malaoxon is shown to form under dry and
microbially inactive environmental conditions, such as on dry soil, concrete, or roofing material,
where oxidation can occur.
2. Ecological Exposure and Risk
To estimate potential ecological risk, EPA integrates the results of exposure and
ecotoxicity studies using the risk quotient method. Risk quotients (RQs) are calculated by
dividing acute and chronic estimated environmental concentrations (EECs), based on
environmental fate characteristics and pesticide use data, by ecotoxicity values for various
wildlife and plant species. RQs are then compared to levels of concern (LOCs), and when the
RQ exceeds the level of concern for a particular category, the Agency presumes a risk of concern
to that category. See Table 15 for the Agency's LOCs. Risk characterization provides further
information on potential adverse effects and the possible impact of those effects by considering
the fate of the chemical and its degradates in the environment, organisms potentially at risk, and
the nature of the effects observed. To the extent feasible, the Agency seeks to reduce
environmental concentrations in an effort to reduce the potential for adverse effects to non-target
organisms.
Table 15. EPA's Levels of Concern (LOCs) and Risk Presumptions
If a calculated RQ is greater than the LOG presented, then the Agency
presumes that...
Acute Risk ...there is potential for acute risk; regulatory action may be
warranted
Acute Listed (Endangered and Threatened) Species ...listed species may be
adversely affected
Chronic Risk . . .there is potential for chronic risk
LOC
terrestrial
animals
0.5
0.1
1
LOC
aquatic
animals
0.5
0.05
1
LOC
Plants
1.0
1.0
NA
In general, ecotoxicity data reveal that on an acute basis, malathion is moderately toxic to
birds and only slightly toxic to mammals through dietary exposure. Malathion has shown to be
more acutely toxic to aquatic species (including freshwater as well as estuarine marine species).
On a chronic basis, malathion is moderately toxic to avian species and less toxic to mammals.
Conversely, malathion is highly toxic to aquatic organisms.
47
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Malathion's mode of action is through acetylcholinesterase (AChE) inhibition which
disrupts nervous system function. Inhibiting this enzyme leads to accumulation of the
neurotransmitter, thus causing signals in the nervous system to persist longer than normal. While
these effects are intended for control of target insects, the toxicological effects of malathion also
occur in other non-targeted organisms exposed to malathion.
The Agency does not believe that the conditions necessary for the formation of malaoxon
exist such that residues of malaoxon will be found in or on the food sources for terrestrial
wildlife. Malaoxon can enter surface water via urban runoff when malathion converts to
malaoxon and is washed off by rainfall. However, the Agency does not expect malaoxon to be a
significant component of the ecological hazard of malathion to non-target organisms. While
other degradates and impurities of malathion exist, they too are not expected to be present in the
environment at concentrations high enough to contribute to the toxicity of malathion to non-
target organisms.
a. Terrestrial Organisms
Birds and Mammals
Residues of malathion from single and multiple application scenarios are expected to
occur on avian and mammalian food items. Predicted maximum and mean concentrations of
pesticide residues from single and multiple applications of malathion are based on the Kenaga
nomogram as modified by Fletcher et al. (1994). Multiple applications of malathion lead to
higher estimated environmental concentrations (EECs) and, therefore, these EECs were
employed in the Agency's screening-level analyses. In cases where estimated RQs exceed the
Agency's LOG, the Agency may refine its assessment by using mean foliar residue
concentrations in estimating exposure. However, because the estimated RQs for terrestrial non-
target organisms are relatively low, the Agency did not refine its assessment.
In estimating foliar residues from multiple applications, EPA employed first order
dissipation calculations and based scenarios on maximum application rates, minimum
application intervals, and maximum number of applications as reported in field trial data
submitted by the technical registrant. The Agency estimated numerous EECs for various food
sources, (grass, fruit and seed) associated with many of the registered malathion use sites.
Acute and chronic terrestrial organism toxicity studies are required to establish the hazard
of malathion to non-target species. Malathion displays low to moderate acute and subacute oral
toxicity to birds. To estimate acute avian risk, the Agency chose to use the toxicity endpoint
from the subacute dietary study with the Ring-necked pheasant. To calculate chronic avian RQs,
the Agency chose the reproduction study in Bobwhite quail as the toxicity reference value.
The Agency requires wild mammal acute toxicity testing on a case-by-case basis,
depending upon the results of lower tier laboratory mammalian studies, intended use pattern, and
48
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pertinent environmental fate characteristics. In the case of malathion, the Agency estimated
acute mammalian risk, using a toxicity reference value (LD50) from the acute toxicity study with
rat. To calculate chronic mammalian RQs, the Agency selected the NOEL from the 2-year
mouse feeding study as the toxicity reference value. Table 16 summarizes the terrestrial toxicity
reference values for malathion.
A number of non-guideline laboratory and field studies, available through open literature,
evaluated the effects of malathion to birds following commercial agricultural applications.
Summaries of study findings are included in the RevisedEFED RED Chapter for Malathion
(2000). In addition, several non-guideline, and field monitoring studies with other non-target
terrestrial organisms (mammals, reptiles, and insects) are also included in the Revised EFED
RED Chapter for Malathion (2000).
Table 16. Terrestrial Toxicity Reference Values for Malathion
Exposure
Scenario
Species
Exposure
Duration
Toxicity
Reference
Value
Toxicity Category/Effect
Avian
Acute
Chronic
Ring-necked
pheasant
Bobwhite quail
8-day dietary
21 -week
dietary
LC50 = 2369
ppm
LOEL = 2400
ppm
Slightly toxic
Growth and viability
Mammalian
Acute
Chronic
Rat
Mice
32-day dietary
2-year chronic
growth study
LD50 = 390
mg/kg
500 ppm
ChE reduction, reduced
bodyweight, reduced pup survival
Based on estimated avian acute RQs, the LOG for non-endangered birds is only slightly
exceeded. However, the acute endangered LOG for birds is exceeded. The chronic RQs for
birds and mammals slightly exceed the LOG of 1.0, which applies to both endangered and non-
endangered species. For mammals, both non-endangered and endangered, acute and chronic
RQs only slightly exceed the LOG. RQs were estimated for many sites. The range of acute and
chronic RQs are presented in Tables 17 and 18, respectively, below. The tables present both
lower and upper bound for malathion use in a commercial agricultural setting using label
recommended application parameters. The lower bound estimate represents the labeled
application rate for a single ULV application to citrus, and the upper bound represents a multiple
EC/WP application to chestnuts (for birds) and to citrus (for mammals).
Table 17. Terrestrial Organism Acute Risk Ran
JCS
Species
Avian
Food Source
Short grass1
Seed
EEC
(ppm)
42 - 1987
1.2- 119
Toxicity Reference
Value
1^50 zojy mg/Kg
RQ
0.01-0.75
0.0004 - 0.04
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Species
Mammal
Food Source
Short grass
Fruit
EEC
(ppm)
43 - 1500
2.7 - 44
Toxicity Reference
Value
LD50 = 390 mg/kg
RQ
0.07-3.65
0.005-0.16
1: estimated concentration of malathion residues on terrestrial short grass, following multiple applications is
representative of foliar food items such as short grass, tall grass, and broadleaf plants.
Table 18. Terrestrial Organism Chronic Risk Ranges
Species
Avian
Mammal
Food Source
Short grass1
Seed
Short grass
Fruit
EEC (ppm)
42-1535
1.2-46
43 - 1500
2.7 - 44
Toxicity Reference
Value
MOTnT^ 1 1 ft r\r\n\
NOEL 500 ppm
RQ
0.4-18.1
0.01-1.1
0.09-3.0
0.005-0.13
1: estimated concentration of malathion residues on terrestrial short grass, following multiple applications is
representative of foliar food items such as short grass, tall grass, and broadleaf plants.
Amphibians and Reptiles
Exposure to amphibians may occur either through surface water contamination from
runoff or drift, or through dermal absorption that may occur from spray drift. EPA has limited
amphibian aquatic toxicity data, and limited data on the possible effects to amphibians from
dermal adsorption of malathion residues. Possible exposure may occur through ingestion or
absorption of water contaminated with malathion. However, acute risk to reptiles is not expected
as they, like mammals, are relatively efficient at detoxifying malathion.
Non-Target Plants and Non-Target Insects
Malathion has been shown to be systemically absorbed into plant tissues. However, the
Agency does not expect malathion to pose a serious risk to terrestrial plants or aquatic algae, as
its mode of action (effects on the nervous system) would not apply. Indeed the Agency has no
reports of adverse reactions of crops or plants to malathion.
Malathion, however, has been shown to be lethal to many species of beneficial insects.
Routes of exposure may either be through direct contact, contact through foliar residues, and
contact with residue coated pollen transported back to nests or hives. A honeybee foliar residue
contact toxicity study indicated that malathion is highly toxic to bees on an acute basis. In
addition several toxicity studies with aquatic insect larvae were conducted by the USFWS which
showed that malathion is highly to very highly toxic to non-target insects with aquatic early life
stages.
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b. Aquatic Organisms
Freshwater and Estuarine Fish and Invertebrates
As noted above, malathion is mobile, and can move from application sites into surface
water and groundwater. Contamination of surface water from commercial agricultural uses
results from both runoff and from off-target drift. Surface water contamination can also occur
from urban runoff from residential uses and wide area applications, i.e., quarantine and public
health mosquitocide uses.
The Agency used a tier two (PRZM-EXAMS model) assessment, on selected crops, to
assess potential risks to aquatic organisms. The PRZM-EXAMS model is used for both
ecological exposure and drinking water concentration exposure. Unlike the drinking water
assessment described in the human health risk assessment section of this document, the exposure
values used in the ecological risk assessment are neither based upon the Index Reservoir (IR),
nor incorporate percent cropped area (PCA) factors, but rather are based upon the "standard
pond" scenario. The "standard pond" scenario is intended to better represent the spatial and
physical qualities of habitats relevant to risk assessment for aquatic non-target organisms such as
ponds, or streams in, and adjacent to, treated agricultural fields. Therefore, the EEC values used
to assess potential exposure and risk to aquatic animals are not the same as those used to assess
exposure and risk to humans from pesticides in drinking water.
The tier two, PRZM-EXAMS water exposure assessment was conducted on four
malathion crops and several non-agricultural use sites. The Pesticide Root Zone Model (PRZM)
simulates the movement of a chemical in unsaturated soil just below the plant root zone. The
Exposure Analysis Modeling System (EXAMS II) is a model that works with the PRZM model
and predicts pesticide concentrations in a simulated pond. Because malathion is registered for
use on over 100 different commercial agricultural crops, tier two EECs could not be generated on
all registered use sites. In choosing crop surrogates for estimating surface water concentrations,
the Agency considered crop location, application parameters, percent crop treated, and percent of
total malathion use on that crop.
Application rates, number of applications and minimum retreatment intervals were based
upon the maximum supported values identified by the technical registrant in residue field trials.
Estimated water concentrations for selected crops are listed below in Table 19.
Table 19. Maximum and Typical EECs for Selected Crops
Site
Citrus
Appl
Max
Typ
Application Rate
Ibs ai/A
6.25
2.5
no. of app
3
1
Retreatment
Interval
30
-
Estimate Environmental Concentration (ppb)
21 day avg.
23.2
7.38
60 day avg.
10.7
2.59
Peak
156
47.3
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Site
Cotton1
Sorghum
Lettuce
Appl
Max
Typ
Max
Typ
Max
Typ
Application Rate
Ibs ai/A
2.5
0.3
1.25
0.8
1.88
2.0
no. of app
25
4
3
1
6
1
Retreatment
Interval
3
3
7
-
5
-
Estimate Environmental Concentration (ppb)
21 day avg.
67.4
1.48
5.0
0.5
6.3
1.58
60 day avg.
47.7
0.5
26.7
0.18
2.98
0.56
Peak
291
7.9
26.7
2.94
15.4
5.63
1: application values for cotton modeled represent old maximum supported values; current maximum supported use
rate for the Boll Weevil Eradication Program is 1.2 Ib ai/A, and current typical application rate is 0.9 Ib ai/A.
Numerous acute and chronic toxicity studies for freshwater and estuarine/marine fish
have been reviewed by EPA. Depending upon species tested, malathion toxicity to freshwater
fish is classified as very highly toxic. Acute and chronic toxicity data for freshwater and
estuarine invertebrates were also required. Based upon these data, malathion is categorized as
highly toxic to freshwater invertebrates. Table 20 summarizes the aquatic toxicity reference
values for malathion.
Table 20. Aquatic Toxicity Reference Values for Malathion
Exposure
Scenario
Species
Exposure
Duration
Toxicity
Reference Value
Toxicity Category/Effect
Freshwater Fish
Acute
Chronic
Bluegill sunfish
Rainbow trout
69 hr
97 day
LC50 = 30 ppb
NOEC 21 ppb
Very highly toxic
LOEC = 44 ppb
Freshwater Invertebrates
Acute
Chronic
Water flea,
Daphnia magna
Water flea,
Daphnia magna
48 hr
21 day
EC50= 1.0 ppb
NOEC = 0.06 ppb
Highly toxic
LOEC = 0.01 ppb
Similar to RQs calculated for terrestrial organisms, aquatic acute and chronic RQs are
derived by dividing the EEC by the LCso or ECso (for acute hazard) and the EEC by the NOEC
(for chronic hazard). Based on actual monitored concentrations, predicted modeling results, and
actual fish kill incidents, there is acute hazard from contamination of aquatic habitats adjacent to,
or within target application areas. Tables 21 and 22 list acute and chronic RQs, respectively, for
selected crops.
Many non-guideline laboratory and field studies on malathion's toxicity to aquatic non-
target organisms have been conducted. These studies report behavioral and biologic effects
which are not investigated or reflected in the guideline studies required by EPA. Summaries of
these studies are included in the Revised EFED RED Chapter for Malathion, (2000).
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Currently, the Agency does not have a model with which to predict concentrations of
malathion in surface water, from home/garden applications, or urban uses. Runoff from these
uses is expected to move over lawns, and impervious surfaces to storm sewers and then to
surface water. Monitoring data from the USGS National Water Quality Assessment program
(NAWQA) between 1992 and 2001 analyzed for malathion in 903 samples from urban streams,
and found malathion at a maximum concentration of 0.648 ppb. Since the NAWQA data is not
targeted, by location or time, it cannot be reliably considered representative of acute
concentrations of malathion that may occur from urban uses. However, the magnitude of the
concentrations sampled in NAWQA suggests that the acute concentrations from agricultural uses
predicted by PRZM/EXAMS modeling is sufficiently conservative to be protective of potential
concentrations from urban uses.
Table 21. Acute Risk Quotient Ranges for Aquatic Fish and Invertebrates
Site
Cotton1
Sorghum
Citrus
Lettuce
Appl
Max
Typ
Max
Typ
Max
Typ
Max
Typ
EEC (ppb)
(peak concentration)
291
7.9
26.7
2.94
162
47.3
15.4
5.63
Toxicity Reference Value
Fish
Bluegill sunfish
LC50 = 30 ppb
Invert
Daphnia magna
EC50= 1.0 ppb
Risk Quotient
Fish
9.7
0.26
0.9
0.09
5.4
1.57
0.5
0.18
Invert
291
8
27
3
162
47
15
6
1: RQs for cotton represent rates used in the BWEP. EEC of 291 is an overestimate as it is based on the old
maximum application rate of 2.5 Ib ai/A. Current maximum application rate for cotton (BWEP) is 1.2 Ib ai/A, and
typical rate is 0.9 Ib ai/A.
Table 22. Chronic Risk Quotient Ranges for Aquatic Freshwater Fish and Invertebrates
Site
Cotton1
Sorghum
Citrus
Lettuce
Appl
Max
Typ
Max
Typ
Max
Typ
Max
Typ
EEC (ppb)
21 day
(used with
invert.)
67.4
1.48
5.0
0.5
25.2
7.38
6.26
1.58
60 day
(used with fish)
47.7
0.5
1.95
0.18
11.1
2.59
2.98
0.56
Toxicity Reference Value
Fish
Rainbow trout
MOFP —
21 ppb
Invert
Daphnia
magna NOEC
= 0.06 ppb
Risk Quotient
Fish
2.3
0.02
0.09
0.01
0.5
0.12
0.14
0.02
Invert2
1123
25
83
8.3
416
121
104
26
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1: RQs for cotton represent rates used in the BWEP. EECs of 67.4, and 47.7 are overestimates as they are based on
old maximum application rates of 2.5 Ib ai/A. Current maximum application rate for cotton (BWEP) is 1.2 Ib ai/A,
and typical rate is 0.9 Ib ai/A.
2: Chronic invertebrate RQs cited in the Revised EFED RED Chapter for Malathion (2000) were incorrectly
calculated using the LOEC (0.1), instead of the NOEC value (0.06), which was used in this table.
RQs used to evaluate risk to all aquatic organisms were based on toxicity data for bluegill
sunfish and Daphnia magna, which are both freshwater species. The risk assessment uses these
organisms to represent both freshwater and estuarine/marine fish and invertebrates, because
AChE inhibition is the same toxic mode of action for all of these taxa. Although there is a wide
range of sensitivity to malathion exposure among aquatic organisms, the data do not indicate a
difference attributable to the type of water body in which the animals live.
Were RQs to be calculated for estuarine/marine fish and invertebrates from
estuarine/marine toxicity data, the finding of potential acute risk would be the same. The LCso of
33 ppb for the most sensitive estuarine/marine fish tested, the sheepshead minnow, is essentially
equivalent to the bluegill sunfish LCso of 30 ppb used in the risk assessment to calculate acute
RQs for all fish. The ECso of 2.2 ppb for the estuarine/marine invertebrate Mysidopsis bahia is
not as low as the Daphnia magna ECso of 1.0 ppb used to calculate the acute RQs for all aquatic
invertebrates. However, the peak EECs from PRZM/EXAMS scenarios representing crops most
likely to be grown in estuarine watersheds (such as cotton, citrus and lettuce) would result in
RQs that exceed the acute LOG for all four of these species, whether from a maximum or typical
application rate.
A similar comparison of the chronic toxicity of malathion to freshwater and
estuarine/marine animals is more difficult, due to a scarcity of laboratory toxicity data. There is
only a single submitted chronic toxicity study for estuarine/marine fish, and no such data for
estuarine/marine invertebrates. As with the assessment of acute risk, freshwater RQs are used to
represent all aquatic organisms because of the equivalence of the mode of toxicity to freshwater
and estuarine/marine fish and invertebrates.
c. Spray Drift
Monitoring results indicate that spray drift can be a significant source of aquatic
contamination, and reducing off-target drift reduces aquatic EECs. Drifting malathion
applications carried by air movement will reach unintended sites. Droplet size, wind speed, and
release height tend to be the most important parameters in determining how much of a pesticide
application will deposit off-target. Applications of nonvolatile oils, as in ULV formulations, do
not evaporate rapidly and, therefore, settle more quickly than ULV formulations that may use
water as a carrier. The AgDRIFT model used by the Agency to estimate buffer zones contains a
sophisticated evaporation algorithm to account for evaporation during droplet's time in the air.
The speed by which droplets fall is exponentially related to their size such that small droplets fall
very slowly, resulting in more nontarget deposition. Application rate is also an important
determinant for off-target spray drift exposure. The application rates EPA modeled were
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representative of the range of rates supported by the technical registrant. Spray drift field studies
show considerable variability in deposition under essentially the same conditions. Therefore,
model estimates used for dissipation distances reflect mean values.
EPA modeled several combinations of wind speed, boom width, and formulation types to
determine distances and related pesticide loading into a "standard pond" from aerial applications
of malathion. The Agency estimated buffer zones that would result in concentrations less than 4
ug/L, the lowest LCso value for fish, and in concentrations less than 20 ug/L, the lower 95th
percentile LCso for a freshwater species reported in EPA's Revised EFED RED Chapter for
Malathion (2000). Model results showed that smaller buffer zones were required when wind
speed is low, boom width is reduced, and non-ULV formulations are used. Model results also
showed that buffer zones for ULV and non-ULV formulations were not necessary to prevent
concentrations at or above 20 ug/L and, therefore, are not presented here. Results of model
estimates of buffer zones, based on varying conditions and at the estimated concentration of 4
ug/L, are summarized below in Table 23.
Table 23. Dissipation Distances from Various Aerial Applications
Wind Speed (mph)
Boom Width
(% of wing span)
ULV
Non-ULV Formulations
(formulations using water carriers)
Most Sensitive Freshwater fish - Rainbow trout: LC50 = 4 ug/L
10
15
60ft
75ft
60ft
75ft
0
0
0
50ft
25ft
100ft
50ft
150ft
d.
Wide Area Treatments with Malathion
Public Health Mosquito Treatment
EPA also conducted a screening-level ecological assessment of the public health use of
malathion as a mosquito adulticide. The malathion mosquito abatement product is only
formulated as an ULV product and is applied either aerially or by truck mounted sprayer. The
Agency calculated aquatic EECs from off-target drift using the Agricultural Dispersal (AGDISP)
model, which estimates the deposition of a compound into a "standard pond" (i.e., one hectare
pond that is two meters deep next to a ten hectare plot).
Input parameters for the AGDISP model are chosen to reflect environmental conditions
under which the mosquitocide product is applied (such as temperature and relative humidity),
application practices (boom width, droplet size, and application rate), and physical characteristics
of the compound (such as the evaporation rate or the volatilization fraction of the compound).
Instead of using existing mosquitocide labels, which vary between manufacturers, the Agency
relied upon labels recently submitted by the malathion technical registrant in connection with
55
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Pesticide Registration (PR) Notice 2005-1. The PR Notice 2005-1 recommended specific label
statements and organization principles intended to improve the lot of existing public health adult
mosquitocide labels by clarifying language regarding environmental hazards posed by
mosquitocide products, and by standardizing use direction and instructions for mosquitocide
applicators.
Several variables drawn from the updated mosquitocide label (in compliance with PR
2005-1) include the proposed minimum release height of 100 feet. The updated labels, in line
with the PR Notice also specify a droplet size of 60 ug. Finally, PR 2005-1 discusses that a
buffer zone around aquatic habitat may not be warranted, noting that protecting human health
from mosquito-borne diseases with pesticides often involves some degree of ecological risk, and
that an aquatic buffer zone may require leaving potentially infested areas untreated. Therefore,
in estimating ecological risk from the mosquitocide application scenario, the Agency assumed a
zero foot buffer zone.
The Agency calculated a worst-case RQ for fish and invertebrates from the wide area
public health use by assuming 100% of product (on a per area basis) drifts into a six foot deep
pond. Estimated acute RQs for fish are 38 and 1.9 for freshwater invertebrates.
Fruit Fly (Quarantine) Treatment
Malathion is also used in liquid bait applications, such as for wide-area quarantine uses to
control the Mediterranean and other fruit fly species. Non-target organisms may be exposed to
the bait formulation of malathion as it is similar to granules foraged by wildlife. Based upon the
current maximum Med-Fly application rate (0.18 Ib ai/A), acute RQs are well below the LOG (<
0.00001) for both mammals and avian species. Chronic RQs were not calculated, since they too
are likely to be below the Agency's LOG.
Other Non-Agricultural Uses
Other wide area, non-agricultural use sites include rangeland/pasture as well as
commercial tree production. In these scenarios, EPA estimated acute RQs for freshwater fish to
range from 36 to 190 for rangeland/pastures and commercial tree farms, respectively. Acute
RQs for freshwater invertebrates ranged from 1.8 to 3.8. Similar to exposure estimates made in
connection with the public health adulticide use, these RQs are considered very conservative as
EPA estimated RQs assuming 100% of the applied product (on a per area basis) deposits into a
subject water body. Wide area uses are intended to disperse and, therefore, 100% deposition is
very unlikely to occur.
e. Down-the-Drain Assessment
The Agency also estimated potential exposure from malathion released into domestic
wastewater which may eventually be introduced into Publicly Owned Treatment Works
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(POTWs) from the pharmaceutical use of malathion. The Agency used the consumer product
exposure model, Exposure and Fate Assessment Screening Tool (E-FAST) (Versar 1999)
developed by OPPT.
The screening-level assessment assumes that in a given year the entire production volume
of malathion pharmaceutical product is parceled out on a daily basis across the U.S. population,
and is then converted to a mass release per capita. This mass is then diluted into the average
daily volume of wastewater released per person per day to arrive at an estimated concentration of
malathion in wastewater prior to entering a treatment facility. The concentration of malathion in
untreated wastewater is then reduced by the fraction removed during the treatment process
before it is released into a river or stream. The remaining pesticide is discharged into surface
water where it is instantaneously diluted and no further removal is assumed.
Based on 2000-2001 production volume of Ovide®, EPA estimates the high-end acute
surface water concentration to be 3.55 x 10"5 ppb, and chronic surface water concentration to be
approximately 2.73 x 10"6. Since Ovide® production has increased since 2000-2001 by
approximately 3-fold, estimated environmental concentrations from down-the-drain sources are
not expected to be greater than 1.0 x 10"4ppb. Because E-FAST is a screening tool, and the
estimated removal of malathion in wastewater of 3% may be an underestimate based on
laboratory data, the estimated surface water concentrations from down-the-drain release of
malathion from the pharmaceutical use remain very low and significantly less than predicted
exposures from agricultural uses of malathion. Therefore, estimated RQs to non-target aquatic
organisms from down-the-drain exposure to malathion is expected to be very low and not of
concern to the Agency.
f. Endangered Species
Based upon the screening-level assessment conducted on malathion, the Agency has
identified several exceedences of the acute and chronic endangered LOG in certain cases for
birds, mammals, fish and invertebrates should exposures actually occur at modeled levels.
Terrestrial Organisms
• Mammals
o Acute RQs for small mammals feeding on short grass exceeded the Agency's
acute endangered LOG for sites with multiple applications at an application rate >
0.1751bai/A.
o Chronic RQs for small mammals exceeded the Agency's acute endangered LOG
for sites with multiple applications at an application rate > 0.61 Ib ai/A.
• Birds
o Acute endangered LOG is exceeded for grass-eating birds at use sites with single
and multiple applications at an application rate > 1.25 Ib ai/A. The Agency's
acute endangered LOG was not exceeded for seed-eating birds.
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o Chronic RQs exceed the endangered LOG for grass-eating birds at use sites with
single and multiple applications at an application rate > 0.175 Ib ai/A and for
seed-eating birds with multiple applications at rates > 0.61 Ib ai/A or with single
applications at rates > 1.56 Ib ai/A.
• Insects and Plants
o Data indicate that malathion may be highly toxic to bees, and has been shown to
be lethal to many species of beneficial insects when used near or over non-
agricultural areas containing beneficial insect populations. However, the Agency
does not yet have a method to estimate risk to bees and other non-target insect
organisms. Therefore, the Agency cannot preclude possible adverse effects to
beneficial and listed insect species. In addition, the Agency does have data with
which to assess the malathion risk to non- target terrestrial plants or aquatic algae,
and while the Agency has no data or reports of adverse reactions of crops or
plants to malathion, it cannot preclude potential adverse effects to non-target
terrestrial plant species.
Aquatic Organisms
• Fish and Invertebrates (fresh water and estuarine/marine)
o The Agency's acute endangered LOG is exceeded for both fish and invertebrates
in all sites modeled with PRZM-EXAMS. However, when typical use parameters
were used to model these five sites, several RQs for fish fell below the Agency's
acute endangered LOG.
The conclusions stated in this document are based solely on EPA's screening-level
assessment and do not constitute "may effect" findings under the Endangered Species Act for
any listed species. Further, potential indirect effects to any species dependent upon a species that
experiences effects from use of malathion can not be precluded based on the screening level
ecological risk assessment.
3. Ecological Incidents
Wildlife incidents which involve aquatic organisms are reported to the Agency by local,
state, other federal agencies, or at times, submitted under FIFRA sec. 6(a)(2). Eighteen of the
twenty two ecological incidents reported to the Agency were related to fish kills, with most
incidents having occurred since 1970 through the present. The highest rate of incidents is
associated with the high volume and heavily monitored Boll Weevil Eradication Program
(BWEP). Mosquito control and Mediterranean Fruit fly control are also associated with several
incident reports. Incidents ranged in magnitude from just 2 fish to over 10,000 fish. The Agency
expects the occurrence of aquatic incidents to decline over time, as the BWEP is a time limited
program. The Agency has only two reported incidents involving terrestrial organisms. In one
incident (1985), extensive mortality to honeybees was recorded and may have been associated
with large area treatment of alfalfa. The second terrestrial incident involved waterfowl and was
considered only to be possibly linked to a wide area (Medfly) treatment with malathion.
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IV. Risk Management, Reregistration, and Tolerance Reassessment
A. Determination of Reregistration Eligibility
Section 4(g)(2)(A) of FIFRA calls for the Agency to determine, after submission of
relevant data concerning an active ingredient, whether or not products containing the active
ingredient are eligible for reregi strati on. The Agency has previously identified and required the
submission of the generic (technical or manufacturing-use grade) data required to support
reregi strati on of products containing malathion as an active ingredient.
The Agency has completed its review of submitted data and its assessment of the dietary,
residential, occupational, and ecological risks associated with the use of pesticide products
containing the active ingredient malathion. Based on these data, the Agency has sufficient
information on the human health and ecological effects of malathion to make its decisions as part
of the tolerance reassessment process under FFDCA and the reregi strati on process under FIFRA,
as amended by FQPA. The Agency has determined that products containing malathion will be
eligible for reregi strati on provided that: (i) the risk mitigation measures outlined in this
document are adopted; and (ii) label amendments are made to reflect these measures. Needed
label changes and language are listed in Section V. Appendix A is a detailed table listing all
malathion uses that are eligible for reregi strati on, or uses which require tolerances or tolerance
consideration. Appendix B identifies generic data requirements that the Agency reviewed as part
of its determination of the reregi strati on eligibility of malathion, and lists the submitted studies
the Agency found acceptable. Data gaps are identified as either outstanding generic data
requirements that have not been satisfied with acceptable data, or additional data necessary to
confirm the decision presented here.
Based on its evaluation of malathion, the Agency has determined that malathion products,
unless labeled and used as specified in Sections IV and V this document, would present risks
inconsistent with FIFRA and FFDCA. Accordingly, should a registrant fail to implement any of
the risk mitigation measures identified in this document, the Agency may take regulatory action
to address the risk concerns from the use of malathion. If all changes outlined in this document
are incorporated into the product labels, then all current risks for malathion will be adequately
mitigated for the purposes of this determination under FIFRA. Additionally, once an endangered
species assessment is completed, further changes to these registrations may be necessary, as
explained in Section IV.C.4. of this document.
B. Public Comments and Responses
Through the Agency's public participation process, EPA worked with stakeholders and
the public to reach the regulatory decisions for malathion. EPA released its revised malathion risk
assessments for public comment on September 23, 2005, for a 60-day public comment period (an
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additional Phase 5 of the public participation process). During the public comment period on the
risk assessments, which closed on November 22, 2005, the Agency received comments from the
technical registrant, American Mushroom Institute, Natural Resources Defense Council, Armed
Forces Pest Management Board, University of Hawaii, U.S. Department of Agriculture, various
water quality associations and mosquito control districts, and others. These comments in their
entirety, responses to the comments, as well as the preliminary and revised risk assessments, are
available in the public docket (EPA-HQ-OPP-2004-0348) and on the internet at
http:www.regulations.gov.
C. Regulatory Position
1. Food Quality Protection Act Findings
a. "Risk Cup" Determination
As part of the FQPA tolerance reassessment process, EPA assessed the risks associated
with this pesticide, as well as cumulative risks from total exposure to registered uses of OP
pesticides. 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 OPs through a common biochemical interaction with the cholinesterase enzyme. The
Agency has determined that, if the mitigation described in this document is adopted and labels
are amended, aggregate human health risks as a result of exposures to malathion are within
acceptable levels. In other words, EPA has concluded that the tolerances for malathion meet
FQPA safety standards. In reaching this determination, EPA has considered the available
information on the special sensitivity of infants and children, as well as exposures to malathion
from all possible sources. In addition, the Agency has concluded that cumulative risks
associated with OP pesticides, including malathion, are also below the Agency's level of
concern.
b. Determination of Safety to U.S. Population
The Agency has determined that the established tolerances for malathion, with
amendments and changes as specified in this document, meet the safety standards under the
FQPA amendments to section 408(b)(2)(D) of the FFDCA, and that there is a reasonable
certainty no harm will result to the general population or any subgroup from the use of
malathion. In reaching this conclusion, the Agency has considered all available information on
the toxicity, use practices and exposure scenarios, and the environmental behavior of malathion.
As discussed in this document, aggregate risks from malathion are below the Agency's level of
concern. In addition, the Agency has concluded that cumulative risks associated with OP
pesticides, including malathion, are also below the Agency's level of concern.
c. Determination of Safety to Infants and Children
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EPA has determined that the established tolerances for malathion, with amendments and
changes as specified in this document, meet the safety standards under the FQPA amendments to
section 408(b)(2)(C) of the FFDCA, that there is a reasonable certainty of no harm for infants
and children. The safety determination for infants and children considers factors on the toxicity,
use practices and environmental behavior noted above for the general population, but also takes
into account the possibility of increased dietary exposure due to the specific consumption
patterns of infants and children, as well as the possibility of increased susceptibility to the toxic
effects of malathion residues in this population subgroup. In addition, the Agency has concluded
that cumulative risks associated with OP pesticides, including malathion, are also below the
Agency's level of concern.
In determining whether or not infants and children are particularly susceptible to toxic
effects from exposure to residues of malathion, the Agency considered the completeness of the
hazard database for developmental and reproductive effects, the nature of the effects observed,
and other information. The Agency has determined that there is evidence that following acute or
repeated dose exposures to malathion, young animals exhibit adverse effects more readily than
adults. The Agency has oral data for this most sensitive subpopulation and is using it to
determine the appropriate point of departure (PoD) for use in assessing risk for acute and chronic
dietary and incidental oral scenarios. In those instances where the Agency is using a PoD
derived on pup data, the FQPA SF is reduced to Ix. The Agency has decided to retain the FQPA
SF (lOx) for those scenarios where the PoD does not already reflect the most sensitive
population (i.e., the PoD is derived from adult animal studies). Consequently, for dermal
exposure scenarios, where the PoD is derived from adult animals and children are expected to be
exposed, the FQPA SF of lOx has been retained. Similarly, for inhalation exposure scenarios
where the endpoint selected is ChE inhibition (in order to aggregate non-occupational exposures)
and the PoD is based on adult animals, the FQPA SF of lOx has also been retained. Finally, the
Agency has retained the FQPA SF of lOx for the bystander inhalation scenario in order to
account for the lack of a NOAEL, severity of effect, as well as any differential in susceptibility
in the young.
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 endocrine effects as the Administrator may designate." Following
recommendations of its Endocrine Disrupter Screening and Testing Advisory Committee
(EDSTAC), EPA determined that there was a scientific basis 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 EPA include evaluations of
potential effects in wildlife. For pesticides, 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
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authority to require the wildlife evaluations. As the science develops and resources allow,
screening for additional hormone systems may be added to the Endocrine Disrupter Screening
Program (EDSP).
In the available toxicity studies on malathion, there was no estrogen or androgen
mediated toxicity. However, thyroid effects were observed in the combined
chronic/carcinogenicity study in rats, which included an increase in parathyroid hyperplasia in
male and female rats, and a significant trend in thyroid follicular cell adenomas and/or
carcinomas and thyroid c-cell carcinomas (all in males). However, the FIFRA SAP did not
consider the thyroid effects of concern or necessarily related to malathion exposure (SAP, 2000).
3. Cumulative Risks
Section 408(b)(2)(D)(v) of FIFRA requires that, when considering whether to establish,
modify, or revoke a tolerance, the Agency consider "available information" concerning the
cumulative effects of a particular pesticide's residues and "other substances that have a common
mechanism of toxicity." Other substances are considered to account for the possibility that low-
level exposures to multiple chemical substances that cause a common effect by a common
mechanism could lead to the same adverse health effect as would a higher level of exposure to
each individual substance.
Malathion is a member of the OP class of pesticides, which share a common mechanism
of toxicity by affecting the nervous system via cholinesterase inhibition. A cumulative risk
assessment, which evaluates exposures based on a common mechanism of toxicity, was
conducted to evaluate the risk from food, drinking water, residential, and other non-occupational
exposures resulting from registered uses of OP pesticides, including malathion. EPA has
concluded that the cumulative risks associated with OP pesticides are below the Agency's level
of concern. For additional information, refer to the OP Cumulative Assessment (2006 Update),
which is available in EPA docket EPA-HQ-OPP-2006-0618 and on EPA's website at
http://www.epa.gov/pesticides/cumulative/.
4. Endangered Species
The Endangered Species Act required federal agencies to ensure that their actions are not
likely to jeopardize listed species or adversely modify designated critical habitat. The Agency
has developed the Endangered Species Protection Program to identify pesticides whose use may
cause adverse impacts on federally listed endangered and threatened species, and to implement
mitigation measures that address these impacts. To assess the potential of registered pesticide
uses that may affect any particular species, EPA puts basic toxicity and exposure data developed
for the REDs into context for individual listed species and considers ecological parameters,
pesticide use information, the geographic relationship between specific pesticide uses and
species locations and biological requirements and behavioral aspects of the particular species.
When conducted, these analyses take into consideration any regulatory changes recommended in
this RED being implemented at that time. A determination that there is a likelihood of potential
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effects to a listed species may result in limitations on the use of the pesticide, other measures to
mitigate any potential effects, and/or consultations with the Fish and Wildlife Service or National
Marine Fisheries Service, as necessary. If the Agency determines use of malathion "may affect"
listed species or their designated critical habitat, EPA will employ the provisions in the Services
regulations (50 CFR Part 402).
The ecological assessment that EPA conducted for this RED does not, in itself, constitute
a determination as to whether specific species or critical habitat may be harmed by the pesticide.
Rather, this assessment serves as a screen to determine the need for any species specific
assessment that will evaluate whether exposure may be at levels that could cause harm to
specific listed species and their critical habitat. That assessment refines the screening-level
assessment to take into account the geographic area of pesticide use in relation to the listed
species, the habits and habitat requirements of the listed species, etc. If the Agency's specific
assessments for malathion result in the need to modify use of the pesticide, any geographically
specific changes to the pesticide's registration will be implemented through the process
described in the Agency's Federal Register Notice (54 FR 27984) regarding implementation of
the Endangered Species Protection Program. Until that species specific analysis is completed,
the risk mitigation measures being implemented through this RED will help to reduce the
likelihood that endangered and threatened species may be exposed to malathion at levels of
concern.
D. Tolerance Reassessment Summary
Tolerance Definition
Tolerances have been established for the residues of malathion per se in/on food/feed
commodities, meat, milk poultry and eggs [40CFR§ 180.111]. Because animal metabolism data
indicate that there is little likelihood of residue transfer to meat, milk, poultry and eggs,
tolerances for malathion residues in these commodities may be revoked.
Tolerances for residues of malathion in/on plant and animal commodities, food
commodities, and feed commodities are currently expressed in terms of malathion per se. Based
on available plant metabolism data, the Agency has determined that the malathion residues of
concern in plants consist of malathion and its metabolite, malaoxon. In vivo, malaoxon is the
active ChE-inhibiting oxon metabolite of malathion, and under certain conditions, malaoxon can
be formed as an environmental breakdown product of malathion. Monitoring data indicate
malaoxon's presence in food. Therefore, tolerance expression should be revised to include
malathion and malaoxon. The tolerance expression for plant commodities needs to be revised in
order to reflect the Agency's determination that the residues of concern are malathion [0,0-
dimethyl dithiophosphate of diethyl mercaptosuccinate] and its metabolite malaoxon [0,0-
dimethyl thiophosphate of di ethyl mercaptosuccinate]. Table 24 summarizes the metabolites and
degradate included in the malathion risk assessment and tolerance expression.
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Table 24. Metabolites and Degradates Included in the Risk Assessment and Tolerance Expression
Matrix
Plants
Livestock
Primary Crop
Rotational Crop
Ruminant
Poultry
Drinking Water
Residues Included in Risk
Assessment
Malathion and malaoxon
Malathion and malaoxon
180.6(a)(3)
180.6(a)(3)
Malathion and malaoxon
Residues included in
Tolerance Expression
Malathion and malaoxon
Malathion and malaoxon
180.6(a)(3)
180.6(a)(3)
Not applicable
The established tolerances for animal commodities should be revoked. The Agency
published a Notice of Request for Deletion of Certain Uses and Directions for Use (FR vol. 56,
No. 52, FRL-3 874-4) in 1991 in which all direct application to livestock was requested for
deletion from malathion labels. No comments have been received by the Agency in support of
these uses, and this use has been removed from almost all labels. Remaining labels with direct
animal treatment will be amended as part of the RED. Since neither malathion nor malaoxon
were observed in eggs, milk, and animal tissues, there is no need for tolerances in these
commodities based on dietary exposure to malathion.
The Agency has recently updated the list of raw agricultural and processed commodities
and feedstuff's derived from crops (Table 1, OPPTS GLN 860.1000). As a result of changes to
Table 1, malathion tolerances for certain raw agricultural commodities (RACs) which have been
removed from the livestock feeds table need to be revoked. Also, some commodity definitions
must be corrected. A summary of malathion tolerance reassessments is presented in Table 25,
below.
Tolerances Listed Under 40 CFR §180.111:
Sufficient data have been submitted (or were translated when appropriate) to reassess the
established tolerances for the following commodities, pending label amendments for some crops:
alfalfa; apricots; asparagus; avocados; barley, grain (postharvest); beans; beets (including tops);
Birdsfoot trefoil, forage ; Birdsfoot trefoil, hay; blackberries; blueberries; boysenberries; carrots;
chayote fruit; chayote roots; cherries; chestnuts; clover; corn, forage; corn, fresh (including sweet
K + CWHR); corn, grain (postharvest); cottonseed; cucumbers; currants; dewberries; eggplants;
figs; flax seed; garlic; grapefruit; gooseberries; grapes; grass; grass, hay; guavas; hops;
horseradish; kumquats; leeks; lemons; lespedeza, hay; lespedeza, straw; limes; loganberries;
lupine, seed; macadamia nuts; mangos; melons; mushrooms; nectarines; oats, grain
(postharvest); okra; onions (including green onions); oranges; papayas; parsnips; passion fruit;
peaches; pears; peas; pecans; peppermint; peppers; pineapples; potatoes; pumpkins; radishes;
raspberries; rice, grain (postharvest); rice, wild; rutabagas; rye, grain (postharvest); salsify
(including tops); shallots; sorghum, grain (postharvest); spearmint; squash, summer and winter;
strawberries; sweet potatoes; tangerines; tomatoes; turnips (including tops); vegetables, leafy,
Brassica (cole); vetch, hay; vetch, straw; walnuts and wheat, grain (postharvest).
64
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Confirmatory data are required to support the reassessed following commodities: apples;
dates; quinces; sorghum, forage; and vegetables, leafy (except Brassicd).
No registrants have committed to support malathion uses on any greenhouse-grown
crops. Therefore, the registered greenhouse uses of malathion on cucumber, endive, lettuce,
radish, tomato, and watercress should be deleted from all malathion end-use product labels. The
reassessment of tolerances has been conducted with the assumption that only field-grown
cucumber, endive, lettuce, radish, tomato, and watercress are supported for reregi strati on.
Due to a lack of support for reregi strati on, the established tolerances for the following
commodities should be revoked concomitant with the deletion of respective crops from all
malathion product labels: almond hulls; almonds; almonds, shells; beets, sugar, roots; beets,
sugar, tops; cowpea, forage; cowpea, hay; cranberries; filberts; lentils; peanut, forage; peanut,
hay; peanuts; peavine, hay; peavines; plums; prunes; safflower, seed; soybeans (dry and
succulent); soybean, forage; soybean, hay; sunflower seeds.
The tolerances for the following commodities should be revoked because they are no
longer considered significant livestock feed items and have been deleted from Table 1 (OPPTS
GLN 860.1000): flax straw; lespedeza, seed (PRE-H); and vetch, seed (PRE-H).
The tolerances for the following animal commodities should be revoked because the
technical registrant(s) have voluntarily requested cancellation of direct animal treatment uses of
malathion to poultry and other livestock including: cattle, fat (PRE-S); cattle, mbyp (PRE-S);
cattle, meat (PRE-S); eggs (from application to poultry; goats, fat (PRE- S); goats mbyp (PRE-
S); goats, meat (PRE-S); hogs, fat (PRE-S); hogs mbyp (PRE-S); hogs, meat (PRE-S); horses, fat
(PRE-S); horses, mbyp (PRE-S); horses, meat (PRE-S); milk, fat (from application to dairy
cows); poultry, fat (PRE-S); poultry, mbyp (PRE-S); poultry, meat (PRE-S); sheep, fat (PRE-S);
sheep, mbyp (PRE-S); and sheep, meat (PRE-S).
Tolerances To Be Proposed Under 40 CFR §180.111:
Tolerances are required and must be proposed, based on available field trial data, for the
following RACs: aspirated grain fractions; barley, straw; corn, field, stover; oats, forage; oats,
straw; radish tops; rice, straw; rye, forage; rye, straw; watercress; wheat, forage; and wheat,
straw. Tolerances are required and must be proposed for the following RACs after adequate data
have been submitted and evaluated: barley, hay; stover; corn, sweet, stover; cotton, gin
byproducts; oats, hay; sorghum, stover; and wheat, hay.
Tolerances need to be proposed on certain processed commodities which showed
significant concentration of residues based on the results of acceptable processing studies. The
results of processing studies which trigger the need for tolerances for the combined residues of
malathion and malaoxon are briefly presented below.
65
-------
The processing data for apple indicate that the combined residues of malathion and
malaoxon concentrated 3.8x in wet pomace, but did not concentrate in apple juice processed
from apples bearing detectable residues of malathion. A tolerance for apple wet pomace needs to
be proposed once adequate field trial data are available for reassessment of the established
tolerance on apples.
The processing data for preharvest-treated field corn grain indicate that the combined
residues of malathion and malaoxon did not concentrate above the limit of detection (0.01 ppm)
in starch, grits, meal, flour, dry- and wet-milled crude oil, dry- and wet-milled refined oil, and
dry- and wet-milled bleached and deodorized oil processed from field corn grain bearing
nondetectable residues of malathion and malaoxon (<0.01 ppm each) following three preharvest
foliar treatments at 5x the maximum single application rate.
The processing data for postharvest-treated field corn grain indicate that the combined
residues of malathion and malaoxon concentrated 1.8x in meal and 2.Ox in flour processed from
field corn grain bearing detectable combined residues of malathion and malaoxon following a
series of postharvest treatments according to the use pattern the registrant wishes to support. The
combined residues did not concentrate in grits, starch and dry- and wet-milled bleached and
deodorized oil. The highest average field trial (HAFT) (combined residues) from trials reflecting
postharvest treatment is 6.79 ppm. Based on this HAFT and the observed concentration factors,
the maximum expected combined residues are 12.2 ppm for meal (6.79 x 1.8) and 13.6 ppm for
flour (6.79 x 2.0). These maximum expected combined residues are higher than the reassessed
tolerance of 8.0 ppm for field corn grain. Therefore, tolerances for the combined residues of
malathion and malaoxon in corn meal and flour at 14.0 ppm must be proposed. Since residues
did not concentrate in dry- and wet-milled bleached and deodorized oil, a tolerance for this
commodity need not be proposed.
The available data for stored field corn processed commodities may be translated to
stored sorghum processed commodities. A tolerance for the combined residues of malathion and
malaoxon in/on sorghum flour need not be established at this time since sorghum flour is used
exclusively in the United States as a component for drywall, and not as either a human food or a
feedstuff.
The processing data for fig indicate that the combined residues of malathion and
malaoxon concentrated 2.9x in dried fig processed from fresh fig bearing detectable residues and
treated at Ix. A tolerance of 2 ppm should be appropriate for dried fig based on the
concentration factor and the highest average field trial.
The mint processing data indicate that the combined residues of malathion and malaoxon
concentrated up to 12.7x in mint oil processed from mint tops bearing detectable residues
following applications at 5x. The HAFT (combined residues) from mint field trials reflecting the
maximum proposed use pattern is 1.1 ppm. Based on this HAFT and the observed concentration
factor, the maximum expected combined residues are 13.97 ppm for mint oil. These maximum
66
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expected combined residues are higher that the reassessed tolerance of 2.0 ppm for peppermint
and spearmint tops. Therefore, tolerances for the combined residues of malathion and malaoxon
in peppermint and spearmint at 15.0 ppm must be proposed.
The processing data for preharvest-treated oranges indicate that the combined residues of
malathion and malaoxon concentrated in oil (>208x) and dried pulp (9.5x) but reduced in juice
(<0.1x) following processing of oranges bearing detectable residues. Based on the results of this
study, and a HAFT of 1.9 ppm, a tolerance of 400 ppm must be proposed for citrus oil and a
tolerance of 20 ppm must be proposed for citrus dried pulp.
The processing data submitted for cottonseed, potatoes, and tomatoes indicate that the
combined residues of malathion and malaoxon did not concentrate in the respective processed
commodities; therefore, tolerances are not required for the processed commodities of these crops.
Additional processing studies remain outstanding for flax and postharvest-treated wheat.
Tolerances Listed Under 40 CFR §180.11 l(a)(2):
The established tolerance for raisins resulting from drying of grapes on treated trays
should be revoked since adequate supporting data are not available and this use is not being
supported for reregi strati on. An acceptable grape processing study reflecting preharvest
treatment has been submitted and evaluated. The grape processing data indicate that the
combined residues of malathion and malaoxon did not concentrate in raisin and juice processed
from grapes bearing detectable residues following treatment with the 5 Ib/gal EC formulation at
5x the maximum single application rate.
Tolerances Listed Under 40 CFR §180.111(ay3):
The established tolerance for refined safflower oil should be revoked since no registrants
have committed to support malathion use on safflower.
Tolerances Listed Under 40 CFR §180.11 l(a)(4):
The conditions listed in 40 CFR §180.111 (a)(4) allowing malathion use for the control of
insects during the drying of grapes (raisins) should be deleted unless the registrant(s) submits
supporting data.
Tolerances Listed Under 40 CFR §180(a)(5):
The tolerances for the following commodities should be revoked because the technical
registrant(s) have voluntarily requested cancellation of animal feed uses: dehydrated citrus pulp
(for cattle feed) and non-medicated cattle feed concentrate blocks.
67
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A summary of malathion tolerance reassessment and recommended modifications
in commodity definitions are presented in Table 25, below.
Table 25: Tolerance Summary for Malathion
Commodity
Tolerance Listed
Under 40 CFR
§180.111
Reassessed
Tolerance1
Comment
[correct commodity definition}
Tolerances Listed Under 40 CFR §180.111 (2)(1)
Alfalfa
Almond, hulls
Almonds, postharvest
Almonds, shells
Apple
Apricot
Asparagus
Avocado
Barley, grain, postharvest
Beans
Beets (including tops)
Beet, sugar, roots
Beets sugar, tops
Blackberry
Blueberry
Boysenberry
Carrots, roots
Cattle, fat (PRE-S)
Cattle, meat byproducts (PRE-S)
Cattle, meat (PRE-S)
Chayote fruit
Chayote roots
Cherry
Chestnut
Clover
Corn, forage
Corn, fresh (including sweet,
135
50
8
50
8
8
8
8
8
8
8
1
8
8
8
8
8
4
4
4
8
8
8
1
135
8
2
125
185
Revoke
Revoke
Revoke
TBD2
1.0
2.0
0.2
8.0
2.0
2.0
4.0
0.5
Revoke
Revoke
6
8
6.0
1
Revoke
Revoke
Revoke
0.2
0.1
3.0
1.0
125
125
5.0
45.0
0.1
[Alfalfa, forage}
[Alfalfa, hay]
Not supported under reregistration
Not supported under reregistration
Not supported under reregistration
Additional apple field trial data are
required as confirmatory data
[Barley, grain (PRE- andPOST-H)}
Translated from wheat data.
[Bean, dry]
[Bean, succulent]
[Beet, garden, tops] translated from
turnip tops data.
[Beet, garden, roots] Translated from
turnip root data.
Not supported under reregistration
Not supported under reregistration
Translated from blackberry and
raspberry data.
[Carrot]
Contingent upon cancellation of direct
animal treatment uses.
Contingent upon cancellation of direct
animal treatment uses.
Contingent upon cancellation of direct
animal treatment uses.
Translated cucumber data.
Translated potato data.
[Clover, forage]
[Clover, hay]
[Corn, field, forage]
[Corn, sweet, forage]
[Com, sweet (K + CWHR)]
68
-------
Commodity
kernel plus cob with husks
removed)
Corn, grain, post harvest
Cotton, undelinted seed
Cowpea, forage
Cowpea, hay
Cranberry
Cucumber
Currant
Dates
Dewberry
Eggplant
Eggs (from application to poultry)
Fig
Filbert
Flax seed
Flax straw
Garlic
Goat, fat (PRE-S)
Goat, meat byproducts (PRE-S)
Goat, meat (PRE-S)
Gooseberry
Grapefruit
Grape
Grass
Grass, hay
Guava
Hog, fat (PRE-S)
Hog, meat byproduct (PRE-S)
Hog, meat (PRE-S)
Hop
Horseradish
Horse, fat (PRE-S)
Horse, meat byproduct (PRE-S)
Horse, meat (PRE-S)
Tolerance Listed
Under 40 CFR
§180.111
8
2
135
135
8
8
8
8
8
8
0.1
8
1
0.1
1
8
4
4
4
8
8
8
135
135
8
4
4
4
1
8
4
4
4
Reassessed
Tolerance1
8.0
20
Revoke
Revoke
Revoke
0.2
8.0
TBD2
6.0
2.0
Revoke
1.0
Revoke
0.10
Revoke
1.0
Revoke
Revoke
Revoke
6.0
4.0
4.0
200
270
1.0
Revoke
Revoke
Revoke
1.0
0.5
Revoke
Revoke
Revoke
Comment
[correct commodity definition}
[Com, field, grain (PRE- and POST- H)}
Not supported under reregistration
Not supported under reregistration
Not supported under reregistration
Translated from blueberry data.
Further confirmatory data required (data
under review)
Translated from blackberry data.
Translated from tomato data.
Contingent upon cancellation of direct
animal treatment uses.
Not supported under reregistration
[Flax, seed}
Not a significant RAC of flax.
Translated from onion bulb data.
Contingent upon cancellation of direct
animal treatment uses.
Contingent upon cancellation of direct
animal treatment uses.
Contingent upon cancellation of direct
animal treatment uses.
Translated from blackberry and
raspberry data.
Translated from orange data.
[Grass, forage}
Contingent upon cancellation of direct
animal treatment uses.
Contingent upon cancellation of direct
animal treatment uses.
Contingent upon cancellation of direct
animal treatment uses.
[Hops, dried]
Translated from turnip root data.
Contingent upon cancellation of direct
animal treatment uses.
Contingent upon cancellation of direct
animal treatment uses.
Contingent upon cancellation of direct
animal treatment uses.
69
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Commodity
Kumquat
Leek
Lemon
Lentil, seed
Lespedeza, hay
Lespedeza, seed
Lespedeza, straw
Lime
Loganberry
Lupine, seed
Mango
Melon
Milk, fat (from application to
dairy cows)
Mushroom
Nectarine
Nut, macadamia
Oat, grain, postharvest
Okra
Onions (including green onion)
Orange, sweet
Papaya
Parsnip
Passion fruit
Peach
Peanut, forage
Peanut, hay
Peanut, postharvest
Pear
Pea
Pea vine, hay
Pea vines
Pecans
Peppermint
Pepper
Pineapple
Plum
Potato
Poultry, fat (PRE-S)
Poultry, meat byproduct (PRE-S)
Poultry, meat (PRE-S)
Tolerance Listed
Under 40 CFR
§180.111
8
8
8
8
135
8
135
8
8
8
8
8
0.5
8
8
1
8
8
8
8
1
8
8
8
135
135
8
8
8
8
8
8
8
8
8
8
8
4
4
4
Reassessed
Tolerance1
4.0
6
4.0
Revoke
185
Revoke
Revoke
4.0
6.0
2.0
0.2
1.0
Revoke
0.2
1.0
0.2
8.0
3.0
1.0
6.0
4.0
1
0.5
0.2
6.0
Revoke
Revoke
Revoke
3.0
2.0
Revoke
Revoke
0.20
2.0
0.5
0.2
Revoke
0.1
Revoke
Revoke
Revoke
Comment
[correct commodity definition}
Translated from orange data.
Translated from green onion data.
Translated from orange data.
Not supported under reregistration
Translated from alfalfa hay data.
Not a significant RAC of lespedeza
Not a significant RAC of lespedeza
Translated from orange data.
Translated from blackberry and
raspberry data.
Translated from dry beans data
Contingent upon cancellation of direct
animal treatment uses.
Translated from apricot data.
[Oats, grain (PRE- and POST-H)}
Translated from wheat grain data.
[Onion, bulb}
[Onion, green}
[Orange}
Translated from turnip root data.
[Passion fruit}
Not supported under reregistration
Not supported under reregistration
Not supported under reregistration
[Pear]
[Pea, succulent} Dry peas not being
supported under reregistration.
Not supported under reregistration
Not supported under reregistration
[Pecan} Translated from walnut data.
[Peppermint}
[Pepper}
[Pineapple]
Not supported under reregistration
[Potato}
Contingent upon cancellation of direct
animal treatment uses.
Contingent upon cancellation of direct
animal treatment uses.
Contingent upon cancellation of direct
70
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Commodity
Plum, prune
Pumpkin
Quince
Radish
Raspberry
Rice, grain, postharvest
Rice, wild
Rutabaga
Rye, grain, postharvest
Safflower, seed
Salsify (including tops)
Shallots
Sheep, fat (PRE-S)
Sheep, meat byproduct (PRE-S)
Sheep, meat (PRE-S)
Sorghum, forage
Sorghum, grain, postharvest
Soybean (dry and succulent)
Soybean, forage
Soybean, hay
Spearmint, tops
Squash, summer and winter
Strawberry
Sunflower, seed (POST-H)
Sweet potato, roots
Tangerine
Tomato
Tolerance Listed
Under 40 CFR
§180.111
8
8
8
8
8
8
8
8
8
0.2
8
8
4
4
4
8
8
8
135
135
8
8
8
8
1
8
8
Reassessed
Tolerance1
Revoke
1.0
TBD2
0.5
6.0
30
30
0.5
8.0
Revoke
4.0
0.5
6.0
Revoke
Revoke
Revoke
TBD2
8.0
Revoke
Revoke
Revoke
2.0
0.2
1.0
1
Revoke
0.1
4.0
2.0
Comment
[correct commodity definition}
animal treatment uses.
Not supported under reregistration.
Translated from melon data.
Translate from apple data. Further
confirmatory data on apple required.
Translated from turnip root data.
[Rice, grain (PRE-H)} Postharvest use
on rice not supported under
reregistration.
[Rice, wild] Translated from rice grain
data.
[Rutabaga] Translated from turnip root
data.
[Rye, grain (PRE- and POST-H)]
Translated from wheat grain data.
Not supported under reregistration
[Salsify, tops (leaves)] Translated from
turnip tops data.
[Salsify, root] Translated from turnip
root data.
[Shallot] Translated from green onion
data.
Contingent upon cancellation of direct
animal treatment uses.
Contingent upon cancellation of direct
animal treatment uses.
Contingent upon cancellation of direct
animal treatment uses.
[Sorghum, forage] Additional data are
required.
[Sorghum, grain (PRE- and POST-H)]
Postharvest data translated from field
corn grain data.
Not supported under reregistration
Not supported under reregistration
Not supported under reregistration
[Spearmint]
[Squash, summer] Translated from
cucumber data.
[Squash, winter] Translated from winter
squash data.
Not supported under reregistration
[Sweet potato] Translated from potato
data.
Translated from orange data.
71
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Commodity
Trefoil, birdsfoot, forage
Trefoil, birdsfoot, hay
Turnip (including tops)
Vegetables, Brassica, leafy, group
5
Vegetables, leafy (except
Brassica)
Vetch, hay
Vetch, seed
Vetch, straw
Walnut
Wheat, grain, postharvest
Tolerance Listed
Under 40 CFR
§180.111
135
135
8
8
8
135
8
135
8
8
Reassessed
Tolerance1
125
185
4.0
0.5
8.0
TBD2
185
Revoke
Revoke
0.2
8
Comment
[correct commodity definition}
[trefoil, forage] Translate alfalfa and
clover data
[trefoil, forage] Translate alfalfa and
clover data
[Turnip, tops]
[Turnip, roots}
[Brassica (cole) leafy vegetables group}
[Vegetables, leafy, except Brassica
group 4} Further data required on
representative commodity, celery.
Based on alfalfa data
Not a RAC of vetch
Not a RAC of vetch
[Walnut}
[Wheat, grain (PRE- andPOST-H)}
Tolerance To Be Proposed Under 40 CFR §180.111 (a)(l)
Apple, wet pomace
Barley, hay
Barley, straw
Citrus, pulp, dried
Citrus, oil
Corn, field, stover
Corn, sweet, stover
Corn, flour
Corn, meal
Cotton, gin byproducts
Fig, dried
Grain, aspirated, grain fractions
Lespedeza, forage
Oats, forage
Oat, hay
Oat, straw
Pineapple, process residue
Peppermint, oil
Radish, tops
Rice, hulls
Rice, straw
Rye, forage
None
None
None
None
None
None
None
None
None
None
None
None
None
None
None
None
None
None
None
None
None
None
TBD2
TBD2
50
20
400
30.0
TBD2
14.0
14.0
TBD2
2.0
700
125
4.0
TBD2
50
0.40
15.0
4.0
150
60
4.0
Level will be determined when RAC
tolerance reassessed. Further data are
required on RAC.
Translate from wheat hay data when
adequate data have been reviewed.
Translated from wheat straw data.
Sweet corn stover data are required.
Cotton gin byproducts data required.
Based on postharvest treated corn grain;
the highest value measured in aspirated
grain fractions.
Translated from alfalfa and clover data.
Translated from wheat forage data.
Translate from wheat hay data when
adequate data reviewed.
Translated from wheat straw data.
Translated from turnip tops data
Translated from wheat forage data.
72
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Commodity
Rye, straw
Sorghum, grain, stover
Spearmint, oil
Vetch, forage
Watercress
Wheat, forage
Wheat, hay
Wheat, straw
Tolerance Listed
Under 40 CFR
§180.111
None
None
None
None
None
None
None
None
Reassessed
Tolerance1
50
TBD2
15.0
125
0.2
4.0
TBD2
50
Comment
[correct commodity definition}
Translated from wheat straw data.
Translated from alfalfa and clover data
Field trial data are required for wheat
hay.
Tolerances Listed Under 40 CFR §180.111 (a)(2)
Raisins
12
Revoke | Not supported under reregistration
Tolerances Listed Under 40 CFR §180.111 (a)(3)
Safflower, refined oil
0.6
Revoke | Not supported under reregistration
Tolerances Listed Under 40 CFR §180.111 (a)(4)
Raisins
exempt
Revoke | Not supported under reregistration
Tolerances Listed Under 40 CFR §180. Ill (a)(5)
Dehydrated citrus pulp [post-H]
Non-medicated cattle feed
concentrate blocks.
50
10
Revoke
Revoke
Not supported under reregistration
Not supported under reregistration
1: The reassessed tolerance levels are contingent upon the recommended label revisions outlined in the
Residue Chemistry Chapter for the Malathion Reregistration Eligibility Decision (RED) Document,
(April 14, 1999)
2: TBD = To be determined
Codex Harmonization
The Codex Aliment Anus Commission has established several maximum residue limits
(Marls) for residues of malathion in/on various raw agricultural and processed commodities. The
Codex MRLs are expressed in terms of malathion per se. Reassessed U.S. tolerances include
both residues of malathion and the metabolite malaoxon. A numerical comparison of the Codex
MRLs and the corresponding reassessed U.S. tolerances is presented in Table 26.
Table 26: Codex MRLs and Applicable U.S. Tolerances for Malathion.
Codex
Commodity, As Defined
Apple
MRL
(mg/kg)
2.0
Step
CXL
Reassessed U.S.
Tolerance, ppm
TBD1
73
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Codex
Commodity, As Defined
Beans, (dry)
Blackberries
Blueberries
Broccoli
Cabbages, Head
Cauliflower
Celery
Cereal grains
Chard
Cherries
Citrus fruits
Common bean
(pods and/or immature seeds)
Dried fruits
Egg plant
Endive
Grapes
Kale
Kohlrabi
Lentil (dry)
Lettuce, Head
Nuts (whole in shell)
Peach
Pear
Peas (pods and succulent=immature seeds)
Peppers
Plums (including prunes)
Raspberries, Red, Black
Root and tuber vegetables
Rye bran, Unprocessed
Rye flour
Rye wholemeal
Spinach
MRL
(mg/kg)
8.0 Po2
8.0
0.5
5.0
8.0
0.5
1.0
8.0 Po 2
0.5
6.0
4.0
2.0
8.0
0.5
8.0
8.0
3.0
0.5
8.0
8.0
8.0
6.0
0.5
0.5
0.5
6.0
8.0
0.5 3
20.0 PoP 4
2.0 PoP 4
2.0 PoP 4
8.0
Step
CXL
CXL
CXL
CXL
CXL
CXL
CXL
CXL
CXL
CXL
CXL
CXL
CXL
CXL
CXL
CXL
CXL
CXL
CXL
CXL
CXL
CXL
CXL
CXL
CXL
CXL
CXL
CXL
CXL
CXL
CXL
CXL
Reassessed U.S.
Tolerance, ppm
2.0
6.0
8.0
8.0
8.0
8.0
TBD
Corn (field), sorghum,
barley, oats, rye, and
wheat grains = 8.0 (POST-
H)
TBD
3.0
4.0
2.0
~
2.0
TBD
4.0
TBD
TBD
Revoke
TBD
~
6.0
3.0
2.0
0.5
Revoke
6
Potato, Sweet potato, beet,
garden, roots; carrots;
horseradish; parsnip;
radish; rutabaga; and
turnip = 0.1
-
-
-
TBD
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Codex
Commodity, As Defined
Strawberry
Tomato
Turnip, Garden
Wheat bran, Unprocessed
Wheat flour
Wheat wholemeal
MRL
(mg/kg)
1.0
3.0
3.0
20.0 PoP 4
2.0 PoP 4
2.0 PoP 4
Step
CXL
CXL
CXL
CXL
CXL
CXL
Reassessed U.S.
Tolerance, ppm
1.0
2.0
4 tops
0.5 roots
-
-
-
1 TBD = To be determined; residue data remain outstanding.
2 Po = Postharvest treatment of the commodity.
3 (Except Turnip, Garden)
4 PoP = Postharvest treatment of the primary food crop.
E. Regulatory Rationale
The following is a summary of the rationale for mitigation measures necessary for
managing risks associated with the use of malathion for malathion products to be eligible for
reregi strati on. Where labelling revisions are warranted, specific language is set forth in the
summary table of Section V.
1. Human Health Risk Management
a.
Acute and Chronic Dietary (Food Only) Mitigation
The estimated acute and chronic dietary risks from malathion, and malaoxon in food
alone, are less than 100% of both the aPAD, and the cPAD and, therefore, are below the
Agency's LOG. Acute dietary exposure to malathion and malaoxon in food at the 99.9th
percentile is 5% of the aPAD for the general U.S. population, and 11% of the aPAD for all
infants (<1 yr old), the most highly exposed population subgroup. The chronic dietary (food)
exposure to malathion and malaoxon is less than 1% of the cPAD for all population subgroups.
No mitigation is required to address either acute or chronic dietary risks from food alone.
b. Residential Risk Mitigation
Residential Handlers and Post-Application
Estimated dermal and inhalation risks for homeowners handling malathion products are
below the Agency's LOG for all handling scenarios. The combined (dermal and inhalation)
MOEs for all scenarios assessed are greater than 100 (ranging from 250 to 13000).
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For all post-application scenarios, estimated dermal and inhalation MOEs for adults and
toddlers are all greater than 100 (ranging from 270 to 7800) and, therefore, do not exceed the
Agency's LOG.
The total combined MOEs for all assessed residential handler and post-application
scenarios assumed to potentially occur the same day are all greater than 100 (ranging from 260 to
670) and, therefore, do not exceed the Agency's LOG. No mitigation is necessary to address
residential handler or post-application risks.
Residential Bystander - Malathion Only
Public Health Mosquito Control. Combined inhalation and dermal short-term risk estimates for
adults (MOEs ranging from 22,000 to 74,000), and combined dermal, inhalation and incidental
oral risk estimates for toddlers (ARIs ranging from 9-20) from post-application exposure to
malathion following public health mosquito treatment with malathion do not exceed the
Agency's LOG. Therefore, no mitigation is necessary.
Boll Weevil Eradication Program. Combined risks from post-application dermal contact,
inhalation and incidental ingestion of malathion residues in areas nearby fields being treated for
boll weevil with the predominant application rate do not exceed the Agency's LOG for adults
(MOE = 3000) or toddlers (ARI = 1.3); therefore, no mitigation is necessary.
Fruit Fly Eradication Treatment. Adult risk from combined dermal and inhalation exposure
following aerial fruit fly treatment does not exceed the Agency's LOG (MOE = 5500).
Likewise, combined exposure to toddlers from dermal, inhalation and incidental oral routes
results in a risk that does not exceed the Agency's LOG (ARI =1.7); therefore, no mitigation is
necessary.
Residential Bystander - Combined Residues of Malathion and Malaoxon
Post-application exposures of toddlers to combined residues of malathion and malaoxon
on hard surfaces following public health mosquitocide, boll weevil eradication treatment, and
fruit fly treatment have been estimated. Risks from individual routes of exposure (dermal and
incidental oral) were combined using an aggregate risk index (ARI) and are not of concern to the
Agency; therefore, no mitigation measures are necessary.
At the maximum 10% malaoxon conversion rate, the estimated ARI from the maximum
use rate (1.2 Ib ai/A) for malathion in the BWEP is above the LOG (ARI = 0.8); however, the
estimated exposures at the predominantly used typical rate (0.9 Ib ai/A) resulted in an ARI = 1,
which is below the Agency's LOG. All other assessed malaoxon conversion scenarios at the
maximum application rate resulted in ARIs that were also below the Agency's LOG.
Information provided by the USD A/APHIS boll weevil eradication program managers indicate
that the maximum use rate (1.2 Ibs ai/A) is used on less than 1% of the acreage currently in the
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active phase of the program. Recognizing that such a small percentage of acres may actually
receive a malathion treatment at the maximum BWEP rate, the likelihood of playground
equipment and/or decks being found within the estimated drift distance used in the assessment
(75 feet) from a field edge is negligible. Furthermore, the BWEP is a time limited program and
is expected to be largely completed by 2009, with each interim year seeing a substantial
reduction in the overall number of cotton acres being treated with malathion.
c. Acute Aggregate Risk Mitigation
To estimate acute aggregate (food + drinking water) risk from malathion, EPA combined
peak EDWCs, which included predicted concentrations of malaoxon, with food residues and
consumption data, and compared this to the acute aPAD. The Agency assessed 16 separate
screening-level model scenarios (PRZM-EXAMS) to evaluate acute aggregate risk for the 100+
agricultural use sites for which malathion is registered. When EPA estimated acute aggregate
risks based on current maximum supported application values, many risks were above the
Agency's LOG (see Table 10). However, when mitigated application values are used in
conjunction with refinements to the drinking water model, the EDWCs are substantially reduced,
and all acute aggregate risk estimates are below the Agency's LOG (<100% of the aPAD) for all
population subgroups, including the highest exposed population subgroup, all infants.
The mitigated application values used to reduce peak EDWCs and, thus, acute aggregate
risks below the Agency's LOG represent either a lower maximum application rate (Ib ai/A),
and/or a reduced number of applications per year. These values were developed in cooperation
with users and growers, Regional Integrated Pest Management (IPM) Centers, USD A, and the
technical registrant. Therefore, the Agency does not believe the mitigated application values,
when implemented, will have an adverse impact on users. Tables 27 and 28 below summarize
the mitigated application rates (Ibs ai/A) and maximum number of applications per year for non-
ULV and ULV applications, respectively, which will be required on all malathion product labels.
Tables 27 and 28 lists only those sites where application values have changed from the currently
supported maximum application values.
For several reasons the Agency believes that even the acute aggregate risk estimates,
based on mitigated application values and refined inputs, do not underestimate risk, since several
assumptions associated with the EDWC may overestimate potential residues in drinking water.
First, the Agency has assumed that 100% of the predicted concentration value at the "edge of the
field" reaches the POTW. However, monitoring data indicates that concentrations of malathion
are likely to decrease as distance from the application site increases. Second, based on
laboratory data and monitoring data, the Agency assumed 100% conversion of malathion to
malaoxon during the water treatment process. However, the Agency lacks data on the
conversion of malathion to malaoxon under varying treatment processes, or under different water
qualities and, therefore, while the assumption of 100% conversion to malaoxon clearly is a
reasonable upper bound estimate, the Agency lacks the data with which to establish a lower
bound rate of conversion. Third, the Agency's drinking water model is designed to predict
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surface water runoff as if a large portion of an entire watershed is treated with a compound at the
same time, and in temporal proximity to a major rainfall event. However, multiple-year data
indicates that malathion is used on a relatively small percent of almost all crops (< 5%), thereby
reducing the probability of large "spikes" of malathion residues in drinking water. Finally,
because acute comparative ChEI data remains outstanding, some uncertainty regarding the
malaoxon TAP (61x) also remains. Upon receipt of the required comparative ChEI data, the
Agency will review the malaoxon TAP, and the associated dietary (food + drinking water) risks
if necessary.
Table 27: Current and Amended Agricultural Use Patterns for Non-ULV Applications
Crop
Apricots
Asparagus
Barley
Beets, garden
Blackberry
Blueberry
Broccoli
Broccoli Chinese
Broccoli raab
Brussels sprouts
Cabbage
Cantaloupe
Carrots
Cauliflower
Chayote fruit
Cherries (sweet)
Cherries (tart)
Chestnut
Chinese greens (Chinese
cabbage)
Collards
Corn, field
Application Values: Max. Appl. Rate (Ib ai/A) x
Max. No. of Appls. Per Year x Retreatment Interval (Days)
Current Maximum Supported
Application Values
3.75x4x7
1.25x9x7
1.25x3x7
1.25x5x7
2.0x4x7
1.25x4x4
1.25x5x7
1.25x5x7
1.25x5x7
1.25x4x7
1.25x10x7
1.0x6x7
1.25x7x7
1.25x5x7
1.88x3x7
3.75x6x7
3.75x6x7
5.0x4x7
1.25x10x7
1.25x10x7
1.25x3x7
Mitigated Application Values
1.5x2x7
1.25x2x7
1.25x2x7
1.25x3x7
2.0x3x7
1.25x3x4
1.25x1x7
1.25x1x7
1.25x1x7
1.25x1x7
1.25x6x7
1.0x2x7
1.25x2x7
1.25x1x7
1.75x2x7
1.75 x4x32
1.75 x4x32
2.5x3x7
1.25x2x7
1.25x3x7
1.0x2x7
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Crop
Corn, sweet
Cucumber
Dandelion
Dates
Eggplant
Eggplant, oriental
Endive
Flax
Figs
Garlic
Grapefruit
Horseradish
Kale
Kohlrabi
Kumquats
Leeks
Lemons
Lettuce, head
Lettuce, leaf
Limes
Loganberry
Macadamia Nut
Melons
Nectarines
Mustard greens
Oats
Okra
Onions, bulb
Application Values: Max. Appl. Rate (Ib ai/A) x
Max. No. of Appls. Per Year x Retreatment Interval (Days)
Current Maximum Supported
Application Values
1.25x5x5
1.88x3x7
2xNS
4.25x6x7
3.43x5x5
1.56x5x5
3.43x5x5
1.56x5x5
1.88xNSxNS
0.5x1
2.5x3x5
1.56x5x7
6.25x3x30
1.25x5x7
1.25x10x7
1.25x10x7
6.25x3x30
1.56x5x7
6.25x3x30
1.88x6x6
1.88x6x5
6.25x3x30
2.0x4x7
0.94x7x7
1.0x6x7
3.75x4x7
1.25x6x7
1.25x3x7
1.5x6x7
1.56x6x7
Mitigated Application Values
1.0x2x5
1.75x2x7
1.25x2x7
4.25x5x7
1.56x4x5
1.56x5x5
1.25x2x7
0.5x3x72
2.0x2x5
1.56x3x7
Rest of US: 4.5x1
CA: 7.5 x I1
1.25x3x7
1.25 x3x52
1.25x2x7
4.5x1x30
1.56x2x7
FL: 4.5 x 1
CA: 7.5 x I1
1.88x2x6
1.88x2x5
Rest of US: 4.5x2x30
CA: 7.5 x I1
2.0x2x7
0.94x2x7
1.0x2x7
3x3x7
1.25 x3x52
1x2x7
1.2x5x7
1.56x2x7
79
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Crop
Onion green
Oranges
Papaya
Parsnip
Passion Fruit
Peaches
Pears
Peas, succulent
Pecans
Peppers
Pineapple
Pumpkin
Radishes
Raspberry
Rice
Rutabagas
Rye
Salsify
Shallots
Spinach
Squash, summer
Squash, winter
Strawberry
Tangelos
Tangerines
Tomatoes
Tomatillo
Turnip, greens, roots
Application Values: Max. Appl. Rate (Ib ai/A) x
Max. No. of Appls. Per Year x Retreatment Interval (Days)
Current Maximum Supported
Application Values
1.56x6x7
6.25x3x30
1.25x13x3
1.25x5x7
1.25x8x7
3.75x5x11
1.25x5x7
2.5x5x7
2.5x3x7
1.56x5x5
5.0x3x7
1.0x6x7
1.25x5x7
2.0x4x7
1.25x3x7
1.25x5x7
1.25x3x7
1.25x5x7
1.56x5x7
2.0x3x7
1.88x3x7
1.0x6x7
2.0x6x7
6.25x3x30
6.25x3x30
3.43x5x5
1.56x5x5
3.43x5x5
1.56x5x5
1.25x5x7
Mitigated Application Values
1.56x2x7
Rest of US: 4.5x1
CA: 7.5 x I1
1.25x4x3
1.25x3x7
1x8x7
3.0x3x11
1.25x2x7
1.0x2x7
2.5x2x7
1.56x2x5
2.0x3x7
1.0x2x7
1.25x3x7
2.0x2x7
1.25x2x7
1.25x3x7
1.0x2x7
1.25x3x7
1.56x2x7
2.0x2x7
1.75x3x7
1.0x3x7
2.0x4x7
Rest of US: 4.5x1
CA: 7.5 x I1
Rest of US: 4.5x1
CA: 7.5 x I1
1.56x4x5
1.56x4x5
greens: 1.25 x 3 x 52
roots: 1.25 x 3 x7
80
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Crop
Watermelons
Wheat, spring
Wheat, winter
Wild rice
Application Values: Max. Appl. Rate (Ib ai/A) x
Max. No. of Appls. Per Year x Retreatment Interval (Days)
Current Maximum Supported
Application Values
1.0x6x7
1.25x3x7
1.25x3x7
1.25x3x7
Mitigated Application Values
1.5x4x7
1.0x2x7
1.0x2x7
1.25x2x7
NS: Not specified
1: Although the single maximum application rate is increased, the number of applications permitted per year
decreased; thus, the overall potential exposure from this use is lower.
2: Retreatment intervals were shortened or additional applications are allowed for these uses based on grower
comments and are supported by existing field trial data.
Table 28: Current and Amended Agricultural Use Patterns for ULV Applications
Crop
Barley
Beans, dry, lima
Beans, snap
Blueberry
Cherries, sweet
Corn, field
Corn, sweet
Grapefruit
Kumquats
Lemons
Limes
Lupine
Oats
Oranges
Rice
Rye
Sorghum
Tangelos
Application Values: Max. Appl. Rate (Ib ai/A) x
Max. No. of Appls. Per Year x Retreatment Interval (Days)
Current Maximum Supported
Application Values
0.61x3x7
0.61x3x7
0.61x3x7
0.77x5x10
1.22x6x7
0.61x3x7
0.61x5x5
0.175x10x7
0.175x10x7
0.175x10x7
0.175x10x7
0.61x3x7
0.61x3x7
0.175x10x7
0.61x3x7
0.61x3x7
0.61x3x7
0.175x10x7
Amended Application Values
0.61x2x7
0.61x2x7
0.61x2x7
0.77x3x10
1.22x4x7
0.61x2x7
0.61x2x5
0.175x3x7
0.175x2x7
0.175x2x7
0.175x1x7
0.61x1x7
0.61x2x7
0.175x2x7
0.61x2x7
0.61x1x7
0.61x2x7
0.175x2x7
81
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Crop
Tangerines
Wheat, spring
Wheat, winter
Wild rice
Application Values: Max. Appl. Rate (Ib ai/A) x
Max. No. of Appls. Per Year x Retreatment Interval (Days)
Current Maximum Supported
Application Values
0.175x10x7
0.61x3x7
0.61x3x7
0.61x3x7
Amended Application Values
0.175x2x7
0.61x2x7
0.61x2x7
0.61x2x7
d. Chronic Aggregate Risk Mitigation
Chronic aggregate risk for malathion and malaoxon from food and drinking water is
below the Agency's LOG for the U.S. general population and all population subgroups. For all
drinking water scenarios assessed, including the worst-case aerial CA lettuce scenario with
maximum application rates, all chronic aggregate dietary exposure from food and drinking water
for the U.S. population and all infants <1 yr, the most highly exposed population subgroup, was
<1% of the cPAD. No mitigation is required for chronic aggregate exposures to malathion.
e. Short-Term Aggregate Risk Mitigation
Short-term aggregate risk combines chronic dietary (food + drinking water) exposure
with short-term residential exposure. Several malathion uses, such as home fogger, or the wide
area treatments, result in short-term residential exposure which could be aggregated with the
chronic dietary to estimate short-term aggregate risk. Among the malathion residential exposure
scenarios, the Agency believes that aerial application of public health use of malathion represents
the most likely and wide spread co-occurring exposure pathway for the general U.S. population.
To be conservative, the Agency assessed this scenario at the 10% conversion rate of malathion to
malaoxon. For more information regarding the transformation of malathion to malaoxon in the
residential exposure and risk analysis, refer to Malathion: Residential Exposure and Risk
Assessment for the Interim Reregistration Eligibility Decision (RED) Document, dated July 6,
2006.
The Agency aggregated the estimated risks from acute aggregate dietary with the
estimated risks from the wide area public health uses of malathion using the Aggregate Risk
Index (ARI) method, since the target MOE for oral exposure (hand to mouth, and dietary) differs
from that of dermal exposure. When using the ARI method, the Agency considers risks equal to
or above 1 to be not of concern. When chronic dietary (food + drinking water) exposure is added
to the residential bystander oral and dermal exposure components from the public health use of
malathion, the total aggregate ARI is 6. The estimated ARI of 6 is below the Agency's LOG
and, therefore, no mitigation is necessary.
While the Agency believes the wide area use of malathion as a public health pesticide is
the most reasonable scenario to aggregate for short-term aggregate risk, it is not the most
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conservative. Rather, the highest estimated risk to a residential bystander from the Boll Weevil
Eradication Program (BWEP). For the BWEP bystander scenario, the Agency estimated risks
using the maximum supported application rate of 1.2 Ib ai/A, and the typical rate of 0.9 Ib ai/A.
When the Agency combined chronic aggregate dietary (food + drinking water) with the BWEP
bystander scenario, using the maximum supported application rate of 1.2 Ib ai/A, the ARI is 0.8
which indicates exposure slightly above the Agency's LOG. However, when the Agency
estimated short-term aggregate risk from the BWEP at the typical rate of 0.9 Ib ai/A, the ARI is
1, which indicates exposure below the Agency's LOG.
The Agency estimated aggregate short-term risks from the BWEP using the 1.2 Ib ai/A,
because it is Agency policy to characterize risk using the maximum supported rate. However,
based on communications with USD A/APHIS, which sponsors the BWEP, the Agency believes
that the typical application rate of 0.9 Ib ai/A is predominantly used and, therefore, the
appropriate rate at which to asses potential residential risk from the BWEP. USD A/APHIS
provided information which characterized the 0.9 Ib ai/A rate (or lower) as the predominant rate
used in the BWEP, as it provides the optimum combination of efficacy, and cost effectiveness.
The 1.2 Ib ai/A rate was mainly used prior to 1997, and is currently maintained by the BWEP for
select situations, such as finishing up the active phase of the program in a certain area with the
objective of preventing boll weevil survival into another season. On an annual basis, the 1.2 Ib
ai/A rate is used on less than 1% of the active program acreage. Therefore, the Agency has a
high degree of confidence that short-term aggregate exposures, using the wide area BWEP
exposure scenario, are below the Agency's LOG, and no mitigation is necessary.
While the short-term aggregate risk incorporating the BWEP is below the Agency's
LOG, the Agency has taken steps to strengthen malathion product labeling for the BWEP. The
Agency has worked with the technical registrant and USDA to develop spray drift label language
for the BWEP. The additional label language will assist program operators to convey more
information on application requirements and potentially reduce spray drift (see Table 30 in
Section V).
f. Occupational Risk Mitigation
A wide range of factors is considered in making risk management decisions for worker
risks. These factors include, in addition to the estimated MOEs, incident data, the nature and
severity of adverse effects observed in the animal studies, uncertainties in the risk assessment,
alternative registered pesticides, the importance of the chemical in integrated pest management
(IPM) programs, and other factors. Mitigation measures may include reducing application rates,
adding personal protective equipment (PPE) to end-product labels, requiring the use of
engineering controls, extending the post-application re-entry period, and other measures.
Handler Risk Mitigation
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Occupational handler (mixers, loaders and applicators) exposure assessments are
completed by the Agency considering the use of baseline PPE and, if warranted, increasing
levels of PPE and engineering controls in order to estimate the potential impact on exposure and
risk. The combined dermal and inhalation target MOE for malathion is 100. When estimated
MOEs for handler risk are less than 100, EPA strives to reduce worker risks through the use of
PPE and engineering controls or other mitigation measures. In some cases, the Agency may
accept MOEs less than 100 when all mitigation measures that are feasible and practical have
been applied, particularly when there are critical pest management needs associated with the use
of the pesticide.
To address handler risks of concern, the Agency is requiring the following PPE and/or
engineering controls be specified on product labels for formulations and use patterns of
malathion, in addition to the use pattern changes identified in Tables 27 and 28, to be eligible for
reregi strati on. Following the implementation of these formulation specific and activity specific
risk mitigation measures, handler risks for malathion will no longer be of concern to the Agency.
• For all malathion formulations and use patterns, flaggers and applicators using motorized
ground equipment are required to wear baseline PPE (long-sleeved shirt, long pants, and
shoes);
• For all malathion formulations and use patterns—except those identified below—baseline
PPE plus chemical-resistant gloves are required for mixers and loaders;
• Closed mixing/loading systems are required for all ULV applications and mixers and
loaders are required to wear baseline PPE, chemical-resistant gloves, and chemical-
resistant apron;
• All wettable powder (WP) formulations must be packaged in water soluble packaging;
• Mixers, loaders and applicators of dust (D) formulations are required to wear coveralls
over long-sleeve shirt and long pants, chemical-resistant gloves, and an 80% PF (quarter-
face dust/mist) respirator;
• For all dip applications, mixers, loaders and applicators are required to wear baseline PPE
plus chemical-resistant gloves, and chemical-resistant apron;
• For all airblast applications applicators are required to wear baseline PPE, chemical-
resistant gloves, and chemical-resistant hat; and
• Enclosed cockpits are required for all aerial applications.
Two formulation specific scenarios assessed lacked data in PHED for evaluation:
loading/applying dusts with a power duster to treat dates and stored grain, and mixing/loading
and applying dips.
Loading and Applying Dusts
The Agency used surrogate data for WP formulations for handlers loading dust
formulations in mechanical dusters for use on stored grain and dates, but has no data available
for assessing individuals who apply or load/apply dusts. A published study, "Malathion
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Deposition, Metabolite Clearance, and Cholinesterase Status of Date Dusters and Harvesters in
California," (2000) authored by Krieger and Dinoff. Arch. Environ. Contain. Toxicol. Volume
38, Pages 546-553, was submitted by the USDA for consideration in this malathion assessment.
The study reports estimated daily exposure doses of from 0.4 - 1.0 mg malathion/kg/day (i.e.,
MOEs ranged from 130 to 3200, if the total dose is attributed to dermal exposure) for handlers
who load/operate power dusters to treat dates with malathion 5% dust. Workers in this study
were already wearing coveralls over baseline attire, gloves and dust/mist respirators. It is not
expected that engineering controls would be feasible to the operator of the power-duster. Thus,
dust formulations are eligible for reregi strati on provided handlers wear coveralls over long-
sleeved shirt and long pants, chemical-resistant gloves, and an 80% PF (quarter-face dust/mist)
respirator. No additional data will be required by the Agency for this scenario.
Mixing/Loading and Applying Dips
Exposure data is not available to assess potential occupational risks associated with
mixing, loading and applying dip applications. Currently the dip application method is only
registered for use on grape roots. The Agency believes the same individual typically mixes,
loads and applies the dip to the grape roots rather than multiple workers being involved in the
operation. The Agency believes that based on the risk estimates for occupational handlers using
the liquid formulation of malathion for agricultural crop uses, which involve much higher
volume of product, baseline PPE and chemical-resistant gloves will be adequately protective for
all dip applications as well. However, to reduce additional exposure that may result from
potential splashing of product onto the individual during the dip application, the Agency is also
requiring chemical-resistant aprons to be worn. Therefore, for dip applications to be eligible for
reregi strati on, handlers must wear baseline PPE, chemical-resistant gloves and chemical-resistant
aprons. No additional data will be required by the Agency for this scenario.
Post-Application Risk Mitigation
Based on the post-application scenarios assessed, the number of days estimated to reach
the target MOE following applications of malathion exceed the current label REI of 12 hours
established under the Worker Protection Standard for some uses. Considering refinements to the
risk assessment, including the use pattern changes identified in Tables 27 and 28, the Agency has
determined that extension of some REIs is needed in order to mitigate risks to workers entering
previously treated areas to conduct various activities.
Generally, occupational post-application risks to workers were not a concern (MOEs
>100) by 24 hours after treatment for the vast majority of malathion use sites, based on the
mitigated use rates and other refinements to the assessment. In general, when application rates
were 4.5 Ib ai/A and higher, the REI needed to achieve risks that are not a concern increased to
two or three days (24 to 72 hours after treatment), depending on the application rate associated
with the crop and the transfer coefficient associated with the post-application activity. For two
tasks with very high transfer coefficients (detasseling/hand harvesting corn with a TC of 17,000
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cm2/hr and girdling/cane turning grapes with a TC of 10,000 cm2/hr), the REI needed to achieve
risks that are not of concern is three days even though the application rates are 2.0 Ib ai/acre or
less.
The Agency, through its regulatory partner, USD A, Office of Pest Management Policy,
contacted land grant universities, regional IPM centers, and grower groups to obtain additional
information about malathion use patterns and post-application worker activities and maximum
feasible REIs. The goal of this exercise was to determine when high contact, high exposure, and
high risk activities were performed relative to malathion application and to collect other
information about malathion use that might factor into the regulatory decision on REIs for this
RED. Based on information provided through this effort, the Agency is confident the extended
REIs necessary to avoid risks of concern will not adversely impact malathion users. Table 29
lists those crops and specific activities (where appropriate) which require REIs of 24 hours or
greater. All other use sites eligible for reregi strati on not listed in these tables are required to
have a 12 hour REI. Following the implementation of these REIs, post-application risks for
malathion will no longer be of concern to the Agency
Table 29. Use Sites Which Require REIs Longer than 12 Hours
Use Sites that Require a 24 Hour REI
Carrot
Celery
Chayote (root, fruit)
Chestnut
Chinese greens
Collards
Cucumber
Dandelion
Endive
Figs
Garlic
Horseradish
Kale
Kohlrabi
Leeks
Lettuce (head, leaf)
Mustard greens
Nectarines
Parsley
Parsnip
Peach
Pecan
Pineapple
Radish
Rutabaga
Salsify
Shallots
Spinach
Summer squash
Swiss chard
Turnips
Walnuts
Yams
Use Sites that Require a Two Day (48 hour) REI
Avocado
Broccoli
Broccoli raab
Brussels sprouts
Cabbage
Cauliflower
Chinese broccoli
Citrus crops @ 4.5 Ib ai/A
Dates
Kumquats (if not w/ citrus)
Use Sites that Require a Three Day (72 hour) REI
Citrus crops @ 7.5 Ib ai/A
Corn (field, seed, sweet, and pop)
detasseling and hand harvesting
only1
Grapes (table, wine, raisin)
girdling and cane turning only1
All other reentry activities for corn and grapes require a 12 hour REI
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2. Non-Target Organism (Ecological) Risk Management
a. Terrestrial Organisms
Birds and Mammals
EPA's screening-level ecological assessment resulted in estimated acute risks to birds
and mammals which only slightly exceeded the Agency's LOG. The highest acute and chronic
RQ for avain species was associated with malathion use on chestnut (0.75 and 18, respectively),
and the highest acute and chronic RQs for mammals was associated with malathion use on citrus
(3.6 and 3, respectively). RQ estimates were based on maximum concentrations of pesticide
residues on animal feed items from multiple applications, and reflect maximum number of
applications and maximum labeled use rates for malathion.
However, through comments and feedback from the user community, and communication
with USDA and the technical registrant, EPA has received agreement to reduce the maximum
application use and number of applications for numerous agricultural uses (see Tables 27 and 28
for summary of amended use rates). Reductions to the use patterns (Ibs ai/A and the maximum
number of applications) will significantly reduce potential malathion residues on food and feed
items through which non-target terrestrial organisms are exposed to malathion. The Agency
expects that while the acute and chronic RQs to both avian and mammalian species will be
greatly reduced when reduced application rates are used, the estimated RQs may not fall entirely
below the Agency's LOG.
In addition, instructions are to be added to the malathion product labels to reduce the
potential for off target spray drift; thus reducing the potential exposure to non-target terrestrial
organisms. Specific label language aimed at reducing off target drift is contained in Table 30.
Non-Target Plants and Non-Target Insects
As stated above, since the mode of action for malathion is well defined (effects nervous
system), and the Agency has no reports of adverse effects to plants, the Agency has no risk
concerns and is not proposing any mitigation measures for exposure to non-target plants.
The Agency has classified malathion as highly toxic to bees; therefore, a precautionary
statement is required on malathion product labels to limit the exposure to honeybees and other
beneficial insects during applications of malathion (see Table 30).
b. Aquatic Organisms
Agricultural Uses
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As stated above, numerous reductions to application rates are to be implemented for
malathion; however, the majority of changes to be made to malathion labels are for reducing the
maximum number of applications per year. Revised exposure assessments indicate that reducing
the number of applications may have a greater impact on reducing potential exposure to non-
target aquatic organisms than a reduction in the application rate. Moreover, a reduction in the
number of applications not only reduces potential accumulation of malathion that may be
transported in surface run-off, but also reduces occurrences of off-target drift.
To further reduce potential exposure to both non-target fish and aquatic invertebrates, the
technical registrant has agreed to add instructions to product labels to reduce potential off-target
drift to aquatic areas, including requirements for a 25 foot buffer zone along aquatic areas for all
non-ULV aerial applications, and a 50 foot buffer zone along aquatic areas for all ULV aerial
agricultural applications. These buffer zones were determined by considering typical application
speed, boom width, and a representative application rate (see Table 23) and are considered to be
protective of the most sensitive freshwater fish species (bluegill sunfish). By imposing language
on product labels to reduce off-target drift and the use of buffer zones, potential exposure to non-
target invertebrates is further reduced.
In addition, since the toxicological response between freshwater fish and estuarine fish is
similar, the Agency expects that the risk reduction being realized for non-target freshwater
organisms will also be seen for non-target estuarine organisms.
Aquatic Risks
Aquatic toxicity data indicates that on an acute basis malathion is classified as highly
toxic to non-target aquatic invertebrates, and very highly toxic to non-target fish. EPA
conducted a Tier II risk assessment using PRZM-EXAMS modeling on several crops to
represent the 100+ agricultural crops for which malathion is registered. For the several
agricultural crop scenarios modeled, the Agency estimated RQs based on both maximum
application values (Ibs ai/A, and maximum number of applications) as well as typical application
values, which better reflect actual field application practices and will be required on product
labels (see Tables 27 and 28). When assessed with maximum application values, most scenarios
resulted in RQs above the Agency's LOG. However, the Agency expects that acute and chronic
RQs to aquatic organisms will be greatly reduced, with RQs for some scenarios being below the
Agency's LOG, when reduced application rates are assessed.
Estimated acute RQs for non-target fish, using maximum application values for
commercial agricultural sites ranged from 0.5 - 5.4, with the highest RQ based on applications to
citrus. When typical application values were used, the range of estimated acute RQs for non-
target fish was from 0.09 - 1.57. Acute RQs for invertebrates were also estimated using both
maximum and typical application values. Estimated acute RQs for invertebrates, based on
maximum application values ranged from 15-162, and when typical application values were
used, RQs ranged from 3 - 47, again with the highest RQ based on application to citrus.
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Based on maximum application rates, estimated chronic RQs for non-target fish ranged
from 0.09 - 0.5; however, when typical application values were used, chronic RQs ranged from
0.01 - 0.12. Estimated chronic RQs for invertebrates ranged from 83 - 416 when maximum
application values were used, and ranged from 8.3 - 121 when typical application values were
used.
Public Health Uses
The Agency conducted a screening-level ecological assessment for the wide area uses of
malathion including public health, fruit fly, and BWEP uses. For public health uses, the Agency
estimated that the acute RQ for freshwater fish is 38, and the acute RQ for invertebrates is 1.9.
However, when the Agency estimated these RQs, it assumed 100% deposition into a six foot
deep pond, which may overestimate potential exposure since modeling information indicates that
some applied material remains aloft and disperses to such a degree, it does not reach the target
site. In addition, the current maximum application rate for public health adulticide is 0.23 Ib
ai/A, which is approximately three times less than the rate assessed in EPA's screening-level
assessment of 2000. Further, comments received during the Phase 5 public comment period
indicate that mosquito control officials typically use rates lower than the current maximum of
0.23 Ib ai/A. Therefore, while the Agency did not revise non-target RQs to reflect more
appropriate application rates, the Agency believes that risks to non-target aquatic organisms from
adult adulticide applications will be lower than those reflected above. However, while the
estimated RQs associated with the public health use of malathion are be lower than 38 and 1.9,
respectively, for fish and invertebrates, some level of risk to non-target aquatic organisms from
this use likely remain.
Malathion, like other adult mosquitocide products, was the subject of PR Notice 2005-1
which aimed to improve current adult mosquitocide labeling to reduce ecological risks and
improve the handling and use of these products. In addition, the Agency has required additional
measures be added to labels for public health mosquito abatement to further reduce potential
bystander and ecological exposure. These measures, listed below, are being required of other
public health mosquito abatement products as well.
• Specify droplet size for aerial and ground applications (see Table 30 for
details);
• Specify minimum release height of 100 ft for planes, and 75 feet for helicopter;
• Specify wind speed for applications; and
• Specify use pattern by setting a single maximum application, and yearly
maximum application rate. (However, public health labels also permit more
frequent applications to be made to prevent or control a threat to public and/or
animal health under certain conditions.)
Wide Area Fruit Fly Treatment
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Based on a screening-level analysis of the fruit fly treatment use, estimated acute RQs
were very low (< 0.00001) and, therefore, below the Agency's LOG. While chronic RQs were
not calculated, the Agency believes them to be similarly low and below the Agency's LOG.
Therefore no mitigation action is required for this use.
Boll Weevil Eradication Program
Based on maximum application rates, the estimated acute RQs for the BWEP were 9.7
for non-target fish and 291 for non-target invertebrates. Estimated chronic RQs ranged from 2.3
for fish to 1123 for invertebrates. For several reasons, the Agency believes that these estimates
are overestimated. First, estimated RQs were based on maximum application values (2.5 Ib ai/A
applied 25 times per year). Currently, the maximum application rate is 1.2 Ib ai/A, and the
predominantly used typical rate is 0.9 Ib ai/A (>99% of treated acreage). Also, based on
communications with USD A/APHIS far fewer applications are typically made in a year.
Secondly, while the BWEP is an eradication program and, therefore, cannot support buffer
zones, it does however require operators to identify natural water bodies as "sensitive areas," and
make efforts to protect sensitive areas from off-target drift. For example, operators are advised
to use ground applications to treat the edge of a field when sensitive areas are adjacent to
application sites.
In addition, the Agency also recognizes that the BWEP is a time limited program, with a
goal of completing the eradication phase by 2009. After such time, the use of malation through
BWEP will be greatly reduced, and so to will potential exposure to non-target organisms.
Reduction to potential exposure is also realized through the BWEP as the National Cotton
Council estimates that areas where the boll weevil has been eradicated via the BWEP have
realized a 40% - 90% reduction in insecticide use on cotton, which is in part because of the
reduction in the use of malathion. For additional information on the direct and indirect benefits
of the BWEP, see section section IV.E.3, Benefits of Malathion to Users.
Urban Uses
One of the risk assessment goals of the Agency is to estimate pesticide exposure through
all significant routes of exposure from both agricultural and non-crop uses. However, the
ecological risk assessment for malathion pesticides focuses primarily on the agricultural and
wide area uses, because pesticide transport models are available to estimate potential aquatic
exposure from these uses. Based on laboratory toxicity tests with aquatic animals, aquatic
exposure could cause adverse effects in the environment.
Malathion is used for a number of non-crop pesticidal uses, including use as a garden
insecticide and as a building perimeter treatment. As described earlier, malathion is used as a
wide-area spray as a mosquito adulticide and by prescription for head-lice control.
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The ecological risk assessment evaluates the head-lice control use with the "down-the-
drain" model E-FAST 2.0. In these simulations, wastewater containing malathion flows from
buildings in which it is used and passes through sanitary sewers and publicly owned treatment
works (POTW) before being discharged to surface water. The E-FAST model uses the total
national production of a pesticide and distributes it among all households in the nation. The
amount of malathion produced for this use was estimated at 100 kg. The assessment uses a
malathion removal efficiency at the POTW of 3%, which was estimated using the model
EPISuite.
Predicted concentrations from E-FAST indicate that the head-lice control use should not
pose a risk to fish and invertebrates. An acute EEC of 3.55 x 10"5 ppb was estimated based on a
high-end stream dilution factor (i.e., upper 10th percentile), and a chronic EEC of 2.73 x 10"6 ppb
was estimated based on a median stream dilution factor (i.e., 50th percentile). These EECs result
in acute and chronic RQs several orders-of-magnitude below the acute, chronic and endangered
species LOCs.
For outdoor urban uses, the Agency assumes that runoff water from rain and/or lawn and
garden watering may transport pesticides to storm sewers and then directly to surface water.
Although malathion use on lawns is not supported, it can be used on ornamentals plants,
including fruit trees, and gardens. Malathion transported by runoff or erosion in an urban setting
would take a path not only over lawns, but also impervious surfaces such as walkways,
driveways and streets. The Agency is unaware of any model which can simulate the different
application methods for urban use and the physical representation of the urban landscape, storm
sewer and receiving water configuration.
There are models available which can be calibrated to simulate sites and pesticides for
which extensive flow and pollutant data have been collected in advance. The HSPF/NPSM
model, for instance, which is included in the EPA's BASINS shell, has been used to calibrate
stream flow and malathion pesticide use data to simulate loading of these pesticides consistent
with concentrations measured in surface water monitoring. Risk assessors with the California
Department of Environmental Protection confirmed in conversations with the Agency that they
also have used watershed models to calibrate previously collected flow and pesticide monitoring
data, but that they did not know of any models capable of predicting concentrations of pesticides
that might occur because of outdoor urban uses.
Development of a screening model which could simulate the fate and transport of
pesticides applied in an urban setting would require a large body of data which is currently
unavailable. For instance, an urban landscape cannot be simulated as easily as an agricultural
field. The PRZM model simulates runoff from an agricultural field using readily available data
describing surface soil characteristics and laboratory data detailing the persistence and mobility
of pesticides in these soils. The agricultural field simulated is homogenously planted to a single
crop, and soil and water are transported from the field to a receiving water body with dimensions
consistent with USDA farm-pond construction guidelines.
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By contrast, an urban landscape or suburban housing development consists of impervious
surfaces such as streets and sidewalks, and pervious surfaces such as lawns and parkland. One
could expect much greater mobility for pesticides applied to impervious surfaces, but laboratory
soil metabolism studies may not provide an accurate measure of the persistence of pesticides on
these surfaces. The path runoff water and eroded sediment might take is less obvious for an
urban setting than an agricultural field. First, an urban landscape cannot be considered
homogeneous, as the proportion of impervious and pervious surfaces varies for different
locations. In addition, the flow path of runoff water and sediment is not necessarily a direct path
over land, but can pass below ground through storm sewer networks, be directed, or slowed by
pumping stations or temporary holding ponds. Finally, the timing and magnitude of urban uses
is less well defined for urban uses than agricultural uses. While agricultural uses would occur
within a predictable window during the growing season, urban uses of malathion, either from
home owner or from different wide area uses may the occur at different times each year, and
might occur at different times within the same watershed.
The apparent difficulties in accurately characterizing surface water contamination via
urban pesticide use also make it difficult to develop an urban pesticide transport model as well as
identify meaningful mitigation at this time. The next opportunity to assess malathion will be
through the new Registration Review program, which is expected to begin in 2007. The purpose
of Registration Review is to ensure the periodic review of all pesticides to make sure they
continue to meet current scientific and regulatory requirements, with the goal of reviewing each
pesticide every fifteen years. The Agency expects to begin malathion within the first several
years of the Registration Review. During the interim, several actions are planned which should
improve the Agency's ability to assess the level of aquatic exposure to pesticides from urban use.
First, research is currently underway which is aimed at defining the conditions of urban pesticide
use that may lead to greater transport. While this research is being conducted on pyrethroids, it
may be applicable to malathion as well. In addition, further investigation into the dominant
urban uses and application practices of malathion, as well as other pesticides, may help
contribute to understanding the contribution malathion may have as a contaminant in urban
runoff. Finally, the Agency will also continue in its efforts to develop a screening-level model
for urban pesticide uses. Advances in the resolution of GIS databases may allow better
representation of the impervious and pervious portions of a typical urban landscape. As
information regarding urban pesticide use and transport becomes clearer, the conceptual model
of how urban transport should be simulated will also become clearer.
Runoff from urban uses of malathion are likely to occur from either outdoor residential uses
(home garden, or home perimeter), or from wide area treatments such as the public health use, or
fruit fly (quarantine) uses. While it is possible that the residential use of malathion contributes to
urban runoff, wide area applications are likely to result in greater deposition on impervious
surfaces, such as rooftops, roads, and driveways and, therefore, lead to larger concentrations of
malathion in urban runoff. While the wide area uses of malathion may be a larger contributor to
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urban runoff compared to the home garden uses, the benefits of the wide area uses are
significant.
3. Benefits of Malathion to Users
FIFRA provides for the Agency to consider the economic, societal, and environmental
costs and benefits of pesticidal use when weighing the risks associated with occupational
(handler and post-application) and ecological exposures. The mitigation measures required for
malathion are based on EPA's review of comments received; direct consultation with other
federal departments, knowledgeable experts, and growers; close evaluation of malathion's use
patterns and user pest management needs; refinements to the risk assessments where appropriate;
and other information available to the Agency.
Based on Agency data, approximately 15 million pounds of malathion active ingredient
are used annually in the US. A large percent of that use, almost 70%, is used on cotton as part of
the USDA Boll Weevil Eradication Program. The program, which began in the late 1970s, has
been the largest consumer of malathion for the past decade or so. In 2006, less than 3,000,000
acres (or approx. 20% of the US cotton acreage) remain in the active eradication phase, with
12,000,000 acres now considered weevil-free and in the post-eradication phase. The program is
expected to be largely complete by 2009 with essentially 100% of US cotton acreage to be
weevil-free and in the post-eradication phase. Malathion use will decline dramatically as the
remaining acres in the active eradication phase of the program are declared weevil-free.
According to the National Cotton Council, in the Southeast, where the weevil has been
eradicated, the combined annual direct economic benefits from increased yields, reduced insect
damage and lower insect control costs are more than $80 million. Additionally, the Council
estimates that by eradicating the boll weevil from the remaining infested areas, cotton growers in
those states will see annual insect control costs reduced by $30 per acre and yield increases of
more than 10%. Eradicated areas have realized a 40% to 90% reduction in insecticide use on
cotton, which in large part is because of the reduction in the use of malathion
(http://www.cotton.org/tech/pest/bollweevil/index.cfm).
For the remainder of malathion uses, two of the most frequently identified reasons it is
used is its low cost when compared to alternatives and the broad spectrum of pests controlled.
Further, for some use sites, malathion is perhaps the only insecticide registered, or one of only a
few. According to comments received from various stakeholders, the broad spectrum of pests
that malathion targets makes its use highly beneficial since the agricultural industry has been
losing a number of insecticides, and the newer insecticides replacing them have chemistries that
target specific insects and are narrow in their spectrum. Additionally, malathion is registered for
use on over 100 crops, most of which are classified as minor crops (grown on <3 00,000 acres),
while many of the alternative pest control options are registered on fewer crops.
Risks were identified for malathion which exceeded the Agency's LOG for certain
terrestrial and aquatic organisms. With the reductions in malathion use rates and number of
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applications allowed per year to such a large percentage of the crop uses, combined with spray
drift buffers, the Agency believes, on balance, that the benefits of malathion outweigh remaining
terrestrial and aquatic organism risks. Therefore, malathion-containing products are eligible for
reregi strati on, provided the risk mitigation measures are adopted and labels are amended
accordingly.
4. Isomalathion
Isomalathion is a known impurity present as a component of malathion during the
manufacturing process. The current upper certified limit of isomalathion in the technical product
is 0.2% by weight. Data submitted by the technical registrant indicate that the presence of
isomalathion, as a percent of the product, increases when malathion is stored under high
temperatures, for long periods of time, or a combination of these two variables. Current
guideline data indicate that malathion is stable for one year, at 25°C (77° F) and under these
conditions, the percent of isomalathion remains below the certified limit. The current storage
statement recommends against product storage in temperatures above 25°C (77° F). In 2004, the
EPA's Office of Enforcement and Compliance Monitoring collected and analyzed product
samples collected from two primary Cheminova distribution centers and found that all samples
were within certified limits. However, since malathion is used in numerous markets on a
national basis, storage conditions are likely to vary greatly once products leave the distribution
center, and depend upon the type of product, and state or region where the product is ultimately
used.
The Agency has limited toxicity data on either isomalthion alone or products containing
elevated levels of isomalathion. The limited data suggests that isomalathion increases the
toxicity of malathion. It is assumed, however, that the current toxicological data base on
malathion reflects the presence of isomalathion up to the certified limit.
To better understand the presence and effect of isomalathion in malathion products, the
Agency is requiring data and/or information to characterize the storage conditions and general
life cycle of malathion products. In addition, the technical registrant has agreed to submit to the
Agency existing data on the formation of isomalathion as well as a 2-year storage stability study,
currently being conducted by the technical registrant to fulfill a FAO/WHO requirement. The
Agency is currently reviewing a battery of acute toxicity data submitted by the technical
registrant on malathion spiked with 0.4% isomalathion. Pending its review of the acute toxicity
data, the Agency may require additional toxicity data on isomalathion, if necessary.
The technical registrant has also agreed to add to malathion product labels an amended
storage stability statement. The amended storage statement differs from the current statement by
advising against storing malathion products for long periods of time and in conditions where the
temperatures are in excess of 25°C (77° F).
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5. Summary of Mitigation Measures
The following mitigation measures are necessary for malathion products to be eligible for
reregi strati on:
• Reduce maximum use patterns for a large number of agricultural crops (see Tables 27
and 28):
o 4 crop uses require reduced maximum application rates only,
o 69 crop uses require reduced maximum allowed number of applications per
year only, and
o 29 crop uses require both reduced maximum application rates and maximum
number of applications allowed per year;
• For all malathion formulations and use patterns, flaggers and applicators using
motorized ground equipment are required to wear baseline PPE (long-sleeved shirt,
long pants, and shoes);
• For all malathion formulations and use patterns—except those identified below—
baseline PPE plus chemical-resistant gloves are required for mixers and loaders;
• Closed mixing/loading systems are required for all ULV applications and mixers and
loaders are required to wear baseline PPE, chemical-resistant gloves, and chemical-
resistant apron;
• All wettable powder (WP) formulations must be packaged in water soluble
packaging;
• Mixers, loaders and applicators of dust (D) formulations are required to wear
coveralls over long-sleeve shirt and long pants, chemical-resistant gloves, and an 80%
PF (quarter-face dust/mist) respirator;
• For all dip applications, mixers, loaders and applicators are required to wear baseline
PPE plus chemical-resistant gloves, and chemical-resistant apron;
• For all airblast applications applicators are required to wear baseline PPE, chemical-
resistant gloves, and chemical-resistant hat;
• Enclosed cockpits are required for all aerial applications;
• REIs are extended for 46 agricultural crops (although most are 12-24 hours) (see
Table 29);
• Buffer zones of 25 feet for all non-ULV applications and 50 feet for all ULV
agricultural applications are required for aerial applications along all water bodies;
• Spray drift management language specific to BWEP and non-BWEP product labels
are to be added; and
• An amended storage stability statement is to be added to product labels advising
against storing malathion products for long periods of time and in conditions where
the temperatures are in excess of 25°C (77 F).
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Unsupported Use Sites
The following use sites have not been included in the revised risk assessments. The
Agency received and published a request from the technical registrants to delete the following
uses from malathion product labels (FRL-3874-4, p. 11420). Following the publication
announcing the request for use deletion, the Agency subsequently received comments indicating
that the uses listed below would not be supported by any interested party. Therefore, the
following uses must be removed from all end-use product labels.
• stored commodity treatment for almonds
• field or garden seeds
• feed rooms
• manure piles
• rabbits on wire
• human clothing (woolens and other fabrics)
• mattresses
• commercial and industrial uses for bagged flour
• cereal processing plants
• edible and inedible commercial establishments
• edible and inedible eating establishments
• edible and inedible food processing plants
• packaged cereals
• pet foods and feed stuff
• dairies/cheese processing plant equipment (food contact)
• forest trees (including Douglas fir, eastern pine, hemlock, larch, pines, red pine,
spruce, and true fir)
• cattle feed concentrate blocks (non-medicated)
• cats
• dogs
• all direct animal and livestock treatments including (goats, hog, horse, poultry, fowl,
sheep and cattle: dairy, non-dairy, lactating and non-lactating)
• animal premise and barns used for dairy and livestock
• tobacco
• stables and pens
• poultry houses
• animal kennels/sleeping quarters (commercial)
• cattle feedlots and holding pens
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In addition, the following use sites/formulations have been requested for deletion by the
technical registrant in a letter to the Agency dated July 25, 2006. The Agency intends to
announce this request in the Federal Register in the near future.
• apples
• commercial shipping containers -feed/food- empty
• commercial storages/ warehouses premises
• commercial transportation facilities -feed/food -empty
• commercial transportation facilities -nonfeed/nonfood
• commercial/institutional/industrial premises/equipment (outdoor)
• commercial/institutional/industrial premises/equipment (indoor)
• golf course turf
• greenhouse -empty
• greenhouse -in use
• lentils
• quince
• residential lawns (broadcast)
• sewage systems
• residential pressurized can formulations
• residential dust formulations
F. Other Labeling Requirements
To be eligible for reregi strati on, various use and safety information will be included in
the labeling of all end-use products containing malathion. For the specific labeling statements
and a list of outstanding data, refer to Section V of this RED document.
1. Endangered Species Considerations
At this time, the Agency is not requiring label changes specific to the protection of listed
species for malathion. If, in the future, specific measures are necessary for the protection of
listed species, the Agency will implement them through the Endangered Species Protection
Program. While RQs exceeded the Agency's endangered species LOG for several taxa (see
Section III), these results were based on a screening-level assessment and do not constitute "may
affect" findings under the Endangered Species Act.
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 address these impacts. The Endangered Species Act (ESA)
requires federal agencies to ensure that their actions are not likely to jeopardize listed species or
adversely modify designated critical habitat. To analyze the potential of registered pesticide uses
that may affect any particular species, EPA uses basic toxicity and exposure data developed for
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the REDs and considers it in relation to individual species and their locations by evaluating
important ecological parameters, pesticide use information, geographic relationship between
specific pesticide uses and species locations, and biological requirements and behavioral aspects
of the particular species, as part of a refined species-specific analysis. When conducted, this
species-specific analysis will take into consideration any regulatory changes recommended in
this RED being implemented at that time.
Following this future species-specific analysis, a determination that there is a likelihood
of potential impact to a listed species or its critical habitat may result in: limitations on the use of
malathion; other measures to mitigate any potential impact; or consultations with the Fish and
Wildlife Service or the National Marine Fisheries Service as necessary. If the Agency
determines that use of malathion "may affect" listed species or their designated critical habitat,
EPA will employ the provisions in the Services regulations (50 CFR Part 402). Until that
species-specific analysis is completed, the risk mitigation measures being implemented through
this RED will reduce the likelihood that endangered and threatened species may be exposed to
malathion at levels of concern. EPA is not requiring specific malathion label language at the
present time relative to threatened and endangered species. If, in the future, specific measures
are necessary for the protection of listed species, the Agency will implement them through the
Endangered Species Protection Program.
2. Spray Drift Management
The Agency has been working closely with stakeholders to develop improved approaches
for mitigating risks to human health and the environment from pesticide spray and dust drift. As
part of the reregi strati on process, EPA will continue to work with all interested parties on this
important issue.
From its assessment of malathion, as summarized in this document, the Agency
concludes that certain drift mitigation measures are needed to address the risks from off-target
drift for malathion, including requirements for medium to coarse droplet size, not applying when
wind velocity exceeds 15 mph or into areas of temperature inversions, and other measures.
Label statements implementing these measures are listed in the "spray drift management" section
of the label table (Table 30) in Section V of this RED document. In the future, malathion
product labels may need to be revised to include additional or different drift label statements.
In addition to generic spray drift management language to the malathion label, the
Agency has required, and the technical registrant has agreed to include on non-BWEP malathion
product labels the requirement of buffer zones along all water bodies of 25 feet for all non-ULV
applications and a 50 feet for all ULV agricultural applications.
Finally, the Agency has worked with UDSA/APHIS to develop spray drift management
language specific to the BWEP, including specifications on droplet size, wind velocity, boom
length, and other measures, for inclusion on the malathion label. The full list of spray drift
measures for the BWEP are listed in Table 30.
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V. What Registrants Need to Do
The Agency has determined that malathion is eligible for reregi strati on provided that the
risk mitigation measures outlined in this document are adopted and label amendments are made
to reflect these measures. To implement the risk mitigation measures, the registrants will be
required to amend their product labeling to incorporate the label statements set forth in the Label
Summary Table in Section C below. In the near future, the Agency intends to issue Data Call-In
(DCI) Notices requiring label amendments, product-specific data and additional generic
(technical grade) data. Generally, registrants will have 90 days from receipt of a DCI to
complete and submit response forms or request time extension and/or waiver requests with a full
written justification. For product-specific data, the registrant will have eight months to submit
data and amended labels. For generic data, due dates can vary depending on the specific studies
being required. Below are tables of additional generic data and label amendments that the
Agency intends to require for malathion to be eligible for reregi strati on.
A. Manufacturing-Use Products
1. Generic Data Requirements
The generic data base supporting the reregi strati on of malathion has been reviewed and
determined to be substantially complete. However, the Agency has identified data necessary to
confirm the reregi strati on eligibility decision for malathion. These studies are listed below and
will be included in the generic DCI for this RED, which the Agency intends to issue at a future
date.
Guideline No.
Study Title
870.7800
835.4300
835.4300
Special study:
81-8-SS
860.1500
Immunotoxicity study with malathion
Aerobic aquatic metabolism with malathion
Aerobic aquatic metabolism with malaoxon
Conversion of malathion to malaoxon on hard dry surfaces
Comparative ChE study with malathion and malaoxon (previously
required 10/2004)
Field crop trials (various crops where data are necessary to support the
established tolerance)
Labeling for Manufacturing-Use Products
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To ensure compliance with FIFRA, manufacturing-use product (MP) labeling should be
revised to comply with all current EPA regulations, PR Notices, and applicable policies. The
MP labeling should bear the labeling contained in Table 30.
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. The Agency intends to issue a separate product-specific data call-in (PDCI), outlining
specific product-specific data requirements.
2. Labeling for End-Use Products
To be eligible for reregi strati on, labeling changes are necessary to implement measures
outlined in Section IV above. Specific language to incorporate these changes is specified in
Table 30. Generally, conditions for the distribution and sale of products bearing old
labels/labeling will be established when the label changes are approved. However, specific
existing stocks time frames will be established case-by-case, depending on the number of
products involved, the number of label changes, and other factors.
C. Labeling Changes Summary Table
For malathion to be eligible for reregi strati on, all malathion labels must be amended to
incorporate the risk mitigation measures outlined in Section IV. Table 30 describes specific
label amendments.
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Table 30 Labeling Changes Summary
In order to be eligible for reregi strati on, amend all product labels to incorporate the risk mitigation measures outlined in
Section IV. The following table describes how language on the labels should be amended.
Table 30: Summary of Labeling Changes for Malathion
Description
Amended Labeling Language
Placement on Label
Manufacturing Use Products
One of these statements
may be added to a label to
allow reformulation of the
product for a specific use
or all additional uses
supported by a formulator
or user group
"Only for formulation into an insecticide or miticide for the following use(s): [fill blank only with those
uses that are being supported by MP registrants]."
"This product can not be formulated into end-use products formulated as a dust with directions for use in
residential settings."
"This product can not be formulated into end-use products that are formulated as a pressurized (i.e.,
aerosol) can."
This product can NOT be formulated into end-use products that contain directions for use on:
• all direct animal and livestock treatments including (goats, hog, horse, poultry, fowl, sheep
and cattle: dairy, non-dairy, lactating and non-lactating)
• animal kennels/sleeping quarters (commercial)
• animal premise and barns used for dairy and livestock
• stables and pens
• poultry houses
• animal kennels/sleeping quarters
• cattle feedlots and holding pens
• feed rooms
• cattle feed concentrate blocks (non-medicated)
• dogs and cats
• pet food and pet stuffs
• cereal processing plants
• packaged cereals
• commercial and industrial uses for bagged flour
• commercial shipping containers -feed/food- empty
• commercial storages/ warehouses premises
Directions for Use
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commercial transportation facilities -feed/food -empty
commercial transportation facilities -nonfeed/nonfood
commercial/institutional/industrial premises/equipment (indoor)
commercial/institutional/industrial premises/equipment (outdoor)
dairies/cheese processing plant equipment (food contact)
edible and inedible commercial establishments
edible and inedible eating establishments
edible and inedible food processing plants
field or garden seeds
forest trees
rabbits on wire
golf course turf
greenhouse - empty, or in-use
human clothing (woolens and other fabrics)
manure piles
mattresses
• quince
• residential lawns (broadcast)
• sewage systems
• lentils
• tobacco
One of these statements
may be added to a label to
allow reformulation of the
product for a specific use
or all additional uses
supported by a formulator
or user group
Directions for Use
"This product may be used to formulate products for specific use(s) not listed on the MP label if the
formulator, user group, or grower has complied with U.S. EPA submission requirements regarding
support of such use(s)."
Environmental Hazards
"This pesticide is toxic to aquatic organisms, including fish and invertebrates^ Do not discharge effluent
containing this product into lakes, streams, ponds, estuaries, oceans, or other waters unless in accordance
with the requirements of a National Pollutant Discharge Elimination System (NPDES) permit and the
permitting authority has been notified in writing prior to discharge. Do not discharge effluent containing
this product to sewer systems without previously notifying the local sewage treatment plant authority.
For guidance, contact your State Water Board or Regional Office of the EPA."
Precautionary Statements
immediately following the
User Safety
Recommendations
End Use Products Intended for Occupational Use (WPS and Non-WPS)
Personal Protective Equipment
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PPE Requirements
Established by the RED1
for liquid concentrate
and wettable powder
end-use products
Note: all wettable powder
products must be in water
soluble packets to be
eligible for reregistration.
Note: if the end-use
product does not contain
directions for use as a dip,
the statement referring to
dip applications may be
eliminated.
Note: if the end-use
product does not contain
directions for use
permitting application with
aerial or motorized ground
equipment, the exception
to the glove statement may
be removed.
"Personal Protective Equipment (PPE)"
"Some materials that are chemical-resistant to this product are (registrant inserts correct chemical-
resistant material). If you want more options, follow the instructions for category [registrant inserts
A,B,C,D,E,F,G,or H] on an EPA chemical-resistance category selection chart."
"For all formulations and all use patterns - mixers, and loaders, applicators, flaggers, and other handlers
must wear:
• Long sleeved shirt and long pants, shoes plus socks, (referred to as "baseline PPE")
For all formulations and all use patterns - mixers and loaders must wear:
• Baseline PPE and,
• Chemical resistant gloves.
For all formulations being applied using either aerial or motorized ground equipment - flaggers and
applicators must wear:
• Baseline PPE; and,
• Chemical resistant gloves such as (registrant insert correct chemical-resistant materials).
For all ULV formulations, applications must be Closed Systems - mixers and loaders must wear:
• Baseline PPE, and,
• Chemical resistant gloves; and,
• Chemical resistant apron
For all dip applications - mixers, loaders, and applicators must wear:
• Baseline PPE; and,
• Chemical resistant gloves; and,
• Chemical resistant apron.
For all airblast applications - applicators must wear:
• Baseline PPE; and,
• Chemical resistant gloves; and,
• Chemical resistant headgear."
"All ULV formulations must be packaged in closed mixing and loading systems."
"All wettable powders (WP) formulations must be packaged in water soluble packaging."
"See engineering controls for additional requirements."
Immediately following/below
Precautionary Statements:
Hazards to Humans and
Domestic Animals
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PPE Requirements
Established by the RED1
for dust end-use
products.
Note: if the end-use
product does not have
directions permitting use
in power duster equipment,
the statements related to
persons participating in
power duster applications
may be removed.
"Personal Protective Equipment (PPE)"
"Some materials that are chemical-resistant to this product are (registrant inserts correct chemical-
resistant material). If you want more options, follow the instructions for category [registrant inserts
A,B,C,D,E,F,G,or H\ on an EPA chemical-resistance category selection chart."
"For all dust formulations - mixers, loaders, and applicators must wear:
• Coveralls over baseline PPE; and,
• Chemical resistant gloves such as (registrant insert correct chemical-resistant materials)', and,
• A NIOSH-approved dust/mist filtering respirator with MSHA/NIOSH approval number prefix TC-
21C or a NIOSH-approved respirator with any N, R, P or HE filter" and,
• Chemical-resistant headgear (if overheat exposure is expected)"
"All other loaders, applicators, and other handlers must wear:
• Baseline PPE; and,
• Chemical resistant gloves, such as (registrant insert correct chemical-resistant materials) when
loading."
Immediately following/below
Precautionary Statements:
Hazards to Humans and
Domestic Animals
PPE Requirements
Established by the RED1
for ready-to-use liquid
products
"Personal Protective Equipment (PPE)"
"Some materials that are chemical-resistant to this product are (registrant inserts correct chemical-
resistant material). If you want more options, follow the instructions for category [registrant inserts
A,B,C,D,E,F,G,or H] on an EPA chemical-resistance category selection chart."
For all ready-to-use liquid products; applicators, and other handlers must wear:
• Baseline PPE
Immediately following/below
Precautionary Statements:
Hazards to Humans and
Domestic Animals
User Safety Requirements
"Follow manufacturer's instructions for cleaning/maintaining PPE. If no such instructions for washables
exist, use detergent and hot water. Keep and wash PPE separately from other laundry."
"Discard clothing and other absorbent materials that have been drenched or heavily contaminated with
this product's concentrate. Do not reuse them."
Precautionary Statements:
Hazards to Humans and
Domestic Animals
immediately following the
PPE requirements
Engineering Controls
Engineering Controls for
liquid concentrate end-
use products which may
"Engineering Controls"
"Pilots must use an enclosed cockpit in a manner that is consistent with the WPS for Agricultural
Precautionary Statements:
Hazards to Humans and
Domestic Animals
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be aerially applied.
Pesticides [40 CFR170.240(d)(6)]. Pilots must wear the PPE required on this labeling for applicators."
(Immediately following PPE
and User Safety
Requirements.)
Engineering Controls for
wettable powders
packaged in water-
soluble packets. All
wettable powders must be
in water soluble packets to
be eligible for
reregistration.
"Engineering Controls"
"Water soluble packets when used correctly qualify as a closed mixing/loading system under the Worker
Protection Standard for Agricultural Pesticides [40 CFR 170.240(d)(4). Mixers and loaders using water
soluble packets must:
> wear the personal protective equipment required on this labeling for mixers and loaders, and
> be provided, have immediately available, and wear in an emergency, such as a broken package,
spill, or equipment breakdown:
> chemical resistant footwear and
> NIOSH-approved respirator equipped with ~ a dust/mist filter with MSHA/NIOSH approval
number prefix TC-21C or - any N, R, P, or HE filter."
"Pilots must use an enclosed cockpit in a manner that is consistent with the WPS for Agricultural
Pesticides [40 CFR170.240(d)(6)]. Pilots must wear the PPE required on this labeling for applicators."
Precautionary Statements:
Hazards to Humans and
Domestic Animals
(Immediately following PPE
and User Safety
Requirements.)
User Safety
Recommendations
"User Safety Recommendations"
"Users should wash hands before eating, drinking, chewing gum, using tobacco, or using the toilet."
"Users should remove clothing/PPE immediately if pesticide gets inside. Then wash thoroughly and put
on clean clothing."
"Users should remove PPE immediately after handling this product. Wash the outside of gloves before
removing. As soon as possible, wash thoroughly and change into clean clothing."
Precautionary Statements
under: Hazards to Humans
and Domestic Animals
immediately following
Engineering Controls
(Must be placed in a box.)
Environmental Hazard
Statement
"This pesticide is toxic to aquatic organisms, including fish and invertebrates."
"Do not apply directly to water, or to areas where surface water is present or to intertidal areas below the
mean high water mark. Do not contaminate water when disposing of equipment washwater or rinsate."
"This product may contaminate water through drift of spray in wind. This product has a high potential
for runoff after application. Use care when applying in or to an area which is adjacent to any body of
water, and do not apply when weather conditions favor drift from target area. Poorly draining soils and
soils with shallow water tables are more prone to produce runoff that contains this product. "
Environmental Hazards
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"A level, well maintained vegetative buffer strip between areas to which this product is applied and
surface water features such as ponds, streams, and springs will reduce the potential for contamination of
water from rainfall-runoff. Runoff of this product will be reduced by avoiding applications when rainfall
is forecasted to occur within 48 hours."
Environmental Hazards for Wide Area Mosquito Adulticide Applications
"When applying as a wide area mosquito adulticide, before making the first application in a season, it is
advisable to consult with the state or tribal agency charged with primary responsibility for pesticide
regulation to determine if other regulatory requirements exist."
"This product is toxic to bees. Do not apply this product while bees are actively visiting a treatment
area."
"When applying as a wide area mosquito adulticide, do not apply over bodies of water (lakes, rivers,
permanent streams, natural ponds, commercial fish ponds, swamps, marshes or estuaries), except when
necessary to target areas where adult mosquitoes are present, and weather conditions will facilitate
movement of applied material away from the water in order to minimize incidental deposition into the
water body."
Restricted-Entry Interval
(for labels with WPS uses)
"Do not enter or allow worker entry into treated areas during the restricted entry interval (REI).
"Required REIs are listed with each crop."
Directions for Use,
Agricultural Use
Requirements Box
Early Entry Personal
Protective Equipment
established by the RED
(for labels with WPS uses)
"PPE required for early entry to treated areas that is permitted under the Worker Protection Standard and
that involves contact with anything that has been treated, such as plants, soil, or water, is:
> coveralls,
> shoes plus socks, and
> chemical-resistant gloves made of any waterproof material."
Place in the Directions for
Use In Agricultural Use
Requirements box,
immediately following the
REI
Entry Restriction for Non-
WPS uses
Entry Restriction for non-WPS uses applied as a spray:
"Do not enter or allow others to enter until sprays have dried."
Entry Restriction for non-WPS uses applied dry:
If no WPS uses on the label,
place the statements in the
Directions for Use Under
General Precautions and
Restrictions.
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"Do not enter or allow others to enter until dusts have settled."
If WPS uses are also on the
labeling, place these
statements in a
NonAgricultural Use
Requirements box as specified
in PR Notice 93 -7 and 93 -11.
General Application
Restrictions (for labels
with WPS uses)
"Do not apply this product in a way that will contact workers or other persons, either directly or through
drift. Only protected handlers may be in the area during application."
Place in the Directions for
Use directly above the
Agricultural Use Box.
Other Application
Restrictions (Risk
Mitigation)
All Products/Formulations Containing Malathion
Delete all directions for use for the following use-patterns:
• all direct animal and livestock treatments including (goats, hog, horse, poultry, fowl, sheep
and cattle: dairy, non-dairy, lactating and non-lactating)
• animal kennels/sleeping quarters (commercial)
• animal premise and barns used for dairy and livestock
• stables and pens
• poultry houses
• animal kennels/sleeping quarters
• cattle feedlots and holding pens
• feed rooms
• cattle feed concentrate blocks (non-medicated)
• dogs and cats
• pet food and pet stuffs
• cereal processing plants
• packaged cereals
• commercial and industrial uses for bagged flour
• commercial shipping containers -feed/food- empty
• commercial storages/ warehouses premises
• commercial transportation facilities -feed/food -empty
• commercial transportation facilities -nonfeed/nonfood
• commercial/institutional/industrial premises/equipment (indoor)
• commercial/institutional/industrial premises/equipment (outdoor)
• dairies/cheese processing plant equipment (food contact)
• edible and inedible commercial establishments
• edible and inedible eating establishments
• edible and inedible food processing plants
Directions for Use
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field or garden seeds
forest trees
rabbits on wire
golf course turf
greenhouse - empty, or in-use
human clothing (woolens and other fabrics)
manure piles
mattresses
quince
residential lawns (broadcast)
sewage systems
lentils
tobacco
All uses at residential sites - for dust formulations only
Buffer Zones
"Buffer Zones for Aerial Application
When making a Non-UL V application with aerial application equipment, a minimum buffer zone of 25
feet must be maintained along any water body.
When making a ULV application with aerial application equipment, a minimum buffer zone of 50 feet
must be maintained along any water body."
In the Directions for Use
section in a section titles:
"Buffer Zones for Aerial
Application"
Storage and Disposal
"Product Name Here should be stored in the original unopened container in a secure, dry place."
"Do not contaminate with other pesticides or fertilizers. The product should never be heated above 55° C
(131°F), and should not be stored for long periods of time at a temperature in excess of 25° C (77° F)."
In the Storage and Disposal
section of the labeling
Products with use
instruction for use as a
Wide Area Mosquito
Adulticide
Note: All product labels must be amended to reflect requirements and recommendations specified in
Pesticide Registration Notice 2005-1.
The following statements must also be added.
"Do not apply more than 0.23 Ib ai/A/day. More frequent treatments may be made to prevent or control a
threat to public and/or animal health determined by a state, tribal or local health or vector control agency
on the basis of documented evidence of disease causing agents in vector mosquitoes or the occurrence of
mosquito-borne diseases in animal or human populations, or if specifically approved by the state or tribe
during a natural disaster recovery effort."
Directions for Use under
General Precautions and
Restrictions
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"Apply when wind speed is greater than or equal to 1 mph."
"Do not apply by fixed wing aircraft at height less than 100 feet, or by helicopter at a height less than 75
feet unless specifically approved by the state or tribe based on public health needs."
"Aerial Application:
Spray equipment must be adjusted so that the median diameter product is less than 60 microns (Dv 0.5 <
60 um) and that 90% of the spray is contained in droplets smaller than 80 (Dv 0.9< 80 urn). The effect of
flight speed and, for non-rotary nozzles, nozzle angle on the droplet size spectrum must be considered.
Directions from the equipment manufacturer or vendor, pesticide registrant or a test facility using a wind
tunnel and laser-based measurement instrument must be used to adjust equipment to produce acceptable
droplet size spectra. Application equipment must be tested at least annually to confirm that pressure at
the nozzle and nozzle flow rate(s) are properly calibrated."
"Ground-based application:
Spray equipment must be adjusted so that the volume median diameter is less than 30 microns (Dv 0.5 <
30 um), and that 90% of the spray is contained in droplets smaller than 50 microns (Dv 0.9 < 50 um).
Directions from the equipment manufacturer or vendor, pesticide registrant or test facility using a laser-
based measurement instrument must be used to adjust equipment to product acceptable droplet size
spectra. Application equipment must be tested at least annually to confirm that pressure at the nozzle and
nozzle flow rate(s) are properly calibrated."
Spray Drift
Observe the following requirements when spraying in the vicinity of aquatic areas such as lakes;
reservoirs; rivers; permanent streams; marshes or natural ponds; estuaries and commercial fish ponds.
"Use the largest droplet size consistent with acceptable efficacy. Formation of very small droplets may
be minimized by appropriate nozzle selection, by orienting nozzles away from the air stream as much as
possible, and by avoiding excessive spray boom pressure."
"For groundboom and aerial applications, use only medium or coarser spray nozzles according to ASAE
(S572) definition for standard nozzles, or a volume mean diameter (VMD) of 300 microns or greater for
spinning atomizer nozzles. Aerial applicators must consider flight speed and nozzle orientation in
determining droplet size."
"Make aerial or ground applications when the wind velocity favors on target product deposition
(approximately 3 to 10 mph). Do not apply when wind velocity exceeds 15 mph. Avoid applications
when wind gusts approach 15 mph. For all non-aerial applications, wind speed must be measured
adjacent to the application site on the upwind side, immediately prior to application."
"Do not make aerial or ground applications into areas of temperature inversions. Inversions are
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characterized by stable air and increasing temperatures with increasing distance above the ground. Mist
or fog may indicate the presence of an inversion in humid areas. Where permissible by local regulations,
the applicator may detect the presence of an inversion by producing smoke and observing a smoke layer
near the ground surface."
"Low humidity and high temperatures increase the evaporation rate of spray droplets and therefore the
likelihood of increased spray drift to aquatic areas. Avoid spraying during conditions of low humidity
and/or high temperatures."
"When applications are made with a cross-wind, the swath will be displaced downwind. The applicator
must compensate for this displacement at the downwind edge of the application area by adjusting the path
of the aircraft upwind."
"For aerial applications, the spray boom should be mounted on the aircraft as to minimize drift caused by
wingtip or rotor vortices. The minimum practical boom length should be used and must not exceed 75%
of wing span or 90% rotor diameter."
"Spray should be released at the lowest height consistent with pest control and flight safety. Applications
more than 10 feet above the crop canopy should be avoided. For groundboom applications, apply with
nozzle height no more than 4 feet above the ground or crop canopy."
"For airblast applications, turn off outward pointing nozzles at row ends and when spraying the outer two
rows. To minimize spray loss over the top in orchard applications, spray must be directed into the
canopy."
Specific Application
Restrictions for Use on
Cotton to Control Boll
Weevil
ULV Malathion Label Regarding Applications Made for Boll Weevil Eradication
"Treatment supervisors and applicators must be aware of all sensitive areas near cotton fields, including:
schools, hospitals, nursing homes, churches, occupied dwellings, parks, recreation areas, bodies of water,
and potential habitat for threatened and endangered species."
"For aerial applications, spray equipment must be adjusted so that the volume median diameter is 100
microns (Dv 0.5 = lOOum) or greater. The effects of flight speed, nozzle angle and type, and pump
pressure on the droplet size spectrum must be considered."
"For aerial applications, the spray boom should be mounted on the aircraft as to minimize drift caused by
wingtip or rotor vortices. The minimum practical boom length should be used and outermost nozzles
must not be placed beyond 75% of the wingspan or rotor diameter."
"Spray should be released at the lowest height consistent with pest control and flight safety. Applications
more than 10 feet above the crop canopy should be avoided."
Directions for Use associated
with the specific crop or use-
site.
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"Global positioning systems (GPS) should be used to guide pilots and to monitor each application."
"Ground equipment should utilize a controlled air flow to facilitate particle size and spray deposition, and
should be used at a vehicle speed of 4 to 10 mph. Spray equipment must be adjusted so that the volume
median diameter is 100 microns (Dv 0.5 = lOOum) or greater."
"Ground equipment should be used to treat field edges when possible, covering areas that can not be
treated effectively with aircraft because of obstructions which may affect applicator safety, or where there
is boll weevil over-wintering habitat adjacent to the treatment area, or if there are adjacent sensitive
areas."
"Do not apply when wind velocity exceeds 10 mph. Treatments should be applied when winds are calm,
or moving away from adjacent sensitive areas."
"When applications are made with a cross-wind, the swath will be displaced downwind. The applicator
must compensate for this displacement at the downwind edge of the application area by adjusting the path
of the aircraft upwind."
"Do not make aerial or ground applications into temperature inversions. Inversions are characterized by
stable air and increasing temperatures with height above the ground. Mist or fog may indicate the
presence of an inversion in humid areas. The applicator may detect the presence of an inversion by
producing smoke and observing a smoke layer near the ground surface."
"Applications will not be made when people are in or near infested cotton fields or, to the degree
possible, when people are present in or near adjacent sensitive areas."
"Application will not be made when rainfall is imminent.
"Before beginning treatment, program personnel shall notify all registered apiarists in or near the
treatment area of the date and approximate time of treatment."
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Alfalfa: the Restricted-Entry Interval (REI) is 12 hours.
Apricot: The Restricted-Entry Interval (REI) is 12 hours. For Non-ULV applications: the maximum
application rate is 1.5 pounds active ingredient per acre; the maximum number of applications per year is
2; and the minimum retreatment interval is 7 days.
Asparagus: The Restricted-Entry Interval (REI) is 12 hours. For Non-ULV applications: the maximum
application rate is 1.25 pounds active ingredient per acre; the maximum number of applications per year
is 2; and the minimum retreatment interval is 7 days.
Avocado: The Restricted-Entry Interval (REI) is 48 hours. The maximum application rate is 4.7 pounds
active ingredient per acre; the maximum number of applications per year is 2; and the minimum
retreatment interval is 30 days.
Barley: The Restricted-Entry Interval (REI) is 12 hours. For Non-ULV applications: the maximum
application rate is 1.25 pounds active ingredient per acre; the maximum number of applications per year
is 2; and the minimum retreatment interval is 7 days. For ULV applications: the maximum application
rate is 0.61 pounds active ingredient per acre; the maximum number of applications per year is 2; and the
minimum retreatment interval is 7 days.
Beans (dry, lima, and snap): The Restricted-Entry Interval (REI) is 12 hours. For ULV applications: the
maximum application rate is 0.61 pounds active ingredient per acre; the maximum number of
applications per year is 2; and the minimum retreatment interval is 7 days.
Beets (including tops): The Restricted-Entry Interval (REI) is 12 hours. For Non-ULV applications: the
maximum application rate is 1.25 pounds active ingredient per acre; the maximum number of
applications per year is 3; and the minimum retreatment interval is 7 days.
Blackberry: The Restricted-Entry Interval (REI) is 12 hours. For Non-ULV applications: the maximum
application rate is 2.0 pounds active ingredient per acre; the maximum number of applications per year is
3; and the minimum retreatment interval is 7 days.
Blueberry: The Restricted-Entry Interval (REI) is 12 hours. For Non-ULV applications: the maximum
application rate is 1.25 pounds active ingredient per acre; the maximum number of applications per year
is 3; and the minimum retreatment interval is 7 days. For ULV applications: the maximum application
rate is 0.77 pounds active ingredient per acre; the maximum number of applications per year is 3; and the
minimum retreatment interval is 10 days.
Boysenberry: The Restricted-Entry Interval (REI) is 12 hours. The maximum application rate is 2.0
Specific Application
Restrictions
(Note: The maximum
allowable rate per crop per
application or per year must
be listed as pounds or gallons
of formulated product per
acre, not solely as pounds
active ingredient per acre.)
Directions for Use
associated with the
specific crop or use-site
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pounds active ingredient per acre; the maximum number of applications per year is 4; and the minimum
retreatment interval is 7days.
Broccoli: The Restricted-Entry Interval (REI) is 48 hours. For Non-ULV applications: the maximum
application rate is 1.25 pounds active ingredient per acre; the maximum number of applications per year
is 2; and the minimum retreatment interval is 7 days.
Broccoli raab: The Restricted-Entry Interval (REI) is 48 hours. For Non-ULV applications: the
maximum application rate is 1.25 pounds active ingredient per acre; the maximum number of
applications per year is 2; and the minimum retreatment interval is 7 days.
Brussels sprouts: The Restricted-Entry Interval (REI) is 48 hours. For Non-ULV applications: the
maximum application rate is 1.25 pounds active ingredient per acre; the maximum number of
applications per year is 2; and the minimum retreatment interval is 7 days.
Cabbage: The Restricted-Entry Interval (REI) is 48 hours. For Non-ULV applications: the maximum
application rate is 1.25 pounds active ingredient per acre; the maximum number of applications per year
is 6; and the minimum retreatment interval is 7 days.
Cabbage, Chinese: The Restricted-Entry Interval (REI) is 48 hours. For Non-ULV applications: the
maximum application rate is 1.25 pounds active ingredient per acre; the maximum number of
applications per year is 6; and the minimum retreatment interval is 7 days.
Cantaloupe: The Restricted-Entry Interval (REI) is 12 hours. For Non-ULV applications: the maximum
application rate is 1.0 pounds active ingredient per acre; the maximum number of applications per year is
2; and the minimum retreatment interval is 7 days.
Carrots, roots: The Restricted-Entry Interval (REI) is 24 hours. For Non-ULV applications: the
maximum application rate is 1.25 pounds active ingredient per acre; the maximum number of
applications per year is 2; and the minimum retreatment interval is 7 days.
Cauliflower: The Restricted-Entry Interval (REI) is 48 hours. For Non-ULV applications: the maximum
application rate is 1.25 pounds active ingredient per acre; the maximum number of applications per year
is 1; and the minimum retreatment interval is 7 days.
Celery: The Restricted-Entry Interval (REI) is 24 hours. The maximum application rate is 1.5 pounds
active ingredient per acre; the maximum number of applications per year is 2; and the minimum
retreatment interval is 7days.
Chayote fruit and roots: The Restricted-Entry Interval (REI) is 24 hours. For Non-ULV applications: the
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maximum application rate is 1.25 pounds active ingredient per acre; the maximum number of
applications per year is 2; and the minimum retreatment interval is 7 days.
Cherry (sweet): The Restricted-Entry Interval (REI) is 12 hours. For Non-ULV applications: the
maximum application rate is 1.75 pounds active ingredient per acre; the maximum number of
applications per year is 6; and the minimum retreatment interval is 3 days. For ULV applications: the
maximum application rate is 1.22 pounds active ingredient per acre; the maximum number of
applications per year is 6; and the minimum retreatment interval is 7 days.
Cherry (tart): The Restricted-Entry Interval (REI) is 12 hours. For Non-ULV applications: the maximum
application rate is 1.75 pounds active ingredient per acre; the maximum number of applications per year
is 6; and the minimum retreatment interval is 3 days. For ULV applications: the maximum application
rate is 1.22 pounds active ingredient per acre; the maximum number of applications per year is 6; and the
minimum retreatment interval is 7 days.
Chestnut: The Restricted-Entry Interval (REI) is 24 hours. For Non-ULV applications: the maximum
application rate is 2.5 pounds active ingredient per acre; the maximum number of applications per year is
3; and the minimum retreatment interval is 7 days.
Chinese Broccoli: The Restricted-Entry Interval (REI) is 48 hours. For Non-ULV applications: the
maximum application rate is 1.25 pounds active ingredient per acre; the maximum number of
applications per year is 1; and the minimum retreatment interval is 7 days.
Chinese Greens (Chinese Cabbage): The Restricted-Entry Interval (REI) is 24 hours. For Non-ULV
applications: the maximum application rate is 1.25 pounds active ingredient per acre; the maximum
number of applications per year is 2; and the minimum retreatment interval is 7 days.
Citrus (grapefruit, lemon, lime, orange, tangerine, and tangelo): The Restricted-Entry Interval (REI) is 72
hours. For Non-ULV applications: the maximum application rate is in California, EITHER 7.5 pounds
active ingredient per acre; the maximum number of applications per year is 1; OR 1.5 pounds active
ingredient per acre; and the maximum number of applications per year is 3, and the minimum retreatment
interval is 30 days. In all other states, EITHER 4.5 pounds active ingredient per acre; with a maximum
number of applications per year is 1; OR 1.5 pounds active ingredient per acre; and the maximum number
of applications per year is 3, and the minimum retreatment interval is 30 days.
Collards: The Restricted-Entry Interval (REI) is 24 hours. For Non-ULV applications: the maximum
application rate is 1.25 pounds active ingredient per acre; the maximum number of applications per year
is 3; and the minimum retreatment interval is 7 days.
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Corn (field): The Restricted-Entry Interval (REI) is 72 hours for detasseling, and 12 hours for all other
activities. For Non-ULV applications: the maximum application rate is 1.0 pounds active ingredient per
acre; the maximum number of applications per year is 2; and the minimum retreatment interval is 7 days.
For ULV applications: the maximum application rate is 0.61 pounds active ingredient per acre; the
maximum number of applications per year is 2; and the minimum retreatment interval is 7 days.
Corn (sweet, pop): The Restricted-Entry Interval (REI) is 72 hours for detasseling, and 12 hours for all
other activities. For Non-ULV applications: the maximum application rate is 1.0 pounds active
ingredient per acre; the maximum number of applications per year is 5; and the minimum retreatment
interval is 5 days. For ULV applications: the maximum application rate is 0.61 pounds active ingredient
per acre; the maximum number of applications per year is 5; and the minimum retreatment interval is 5
days.
Cucumber: The Restricted-Entry Interval (REI) is 24 hours. For Non-ULV applications: the maximum
application rate is 1.75 pounds active ingredient per acre; the maximum number of applications per year
is 2; and the minimum retreatment interval is 7 days.
Currant: The Restricted-Entry Interval (REI) is 12 hours. The maximum application rate is 1 pounds
active ingredient per acre; the maximum number of applications per year is 1.
Dandelion: The Restricted-Entry Interval (REI) is 24 hours. For Non-ULV applications: the maximum
application rate is 1.25 pounds active ingredient per acre; the maximum number of applications per year
is 2; and the minimum retreatment interval is 7 days.
Dates: The Restricted-Entry Interval (REI) is 48 hours. For Non-ULV applications: the maximum
application rate is 4.25 pounds active ingredient per acre; the maximum number of applications per year
is 5; and the minimum retreatment interval is 7 days.
Dewberry: The Restricted-Entry Interval (REI) is 12 hours. The maximum application rate is 2.0 pounds
active ingredient per acre; the maximum number of applications per year is 4; and the minimum
retreatment interval is 7 days.
Eggplant: The Restricted-Entry Interval (REI) is 12 hours. For Non-ULV applications: the maximum
application rate is 1.56 pounds active ingredient per acre; the maximum number of applications per year
is 4; and the minimum retreatment interval is 5 days.
Eggplant (Oriental): The Restricted-Entry Interval (REI) is 12 hours. For Non-ULV applications: the
maximum application rate is 1.56 pounds active ingredient per acre; the maximum number of
applications per year is 5; and the minimum retreatment interval is 5 days.
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Endive: The Restricted-Entry Interval (REI) is 24 hours. For Non-ULV applications: the maximum
application rate is 1.25 pounds active ingredient per acre; the maximum number of applications per year
is 2; and the minimum retreatment interval is 7 days.
Fig: The Restricted-Entry Interval (REI) is 24 hours. For Non-ULV applications: the maximum
application rate is 2.0 pounds active ingredient per acre; the maximum number of applications per year is
2; and the minimum retreatment interval is 5 days.
Flax: The Restricted-Entry Interval (REI) is 12 hours. For Non-ULV applications: the maximum
application rate is 0.5 pounds active ingredient per acre; the maximum number of applications per year is
32; and the minimum retreatment interval is 7 days.
Garlic: The Restricted-Entry Interval (REI) is 24 hours. For Non-ULV applications: the maximum
application rate is 1.56 pounds active ingredient per acre; the maximum number of applications per year
is 3; and the minimum retreatment interval is 7 days.
Gooseberry: The Restricted-Entry Interval (REI) is 12 hours. The maximum application rate is 2.0
pounds active ingredient per acre; the maximum number of applications per year is 2; and the minimum
retreatment interval is 7days.
Grapefruit (California only): The Restricted-Entry Interval (REI) is 72 hours. For Non-ULV
applications: the maximum application rate is 7.5 pounds active ingredient per acre; the maximum
number of applications per year is 1. For ULV applications: the maximum application rate is 0.175
pounds active ingredient per acre; the maximum number of applications per year is 3; and the minimum
retreatment interval is 7 days.
Grapefruit (U.S., except California): The Restricted-Entry Interval (REI) is 48 hours. For Non-ULV
applications: the maximum application rate is 4.5 pounds active ingredient per acre; the maximum
number of applications per year is 1. For ULV applications: the maximum application rate is 0.175
pounds active ingredient per acre; the maximum number of applications per year is 3; and the minimum
retreatment interval is 7 days.
Grapes: The Restricted-Entry Interval (REI) is 72 hours for girdling and tying, and 24 hours for all other
activities. The maximum application rate is 1.88 pounds active ingredient per acre; the maximum
number of applications per year is 2; and the minimum retreatment interval is 14 days.
Horseradish: The Restricted-Entry Interval (REI) is 24 hours. For Non-ULV applications: the maximum
application rate is 1.25 pounds active ingredient per acre; the maximum number of applications per year
is 3; and the minimum retreatment interval is 7 days.
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Kale: The Restricted-Entry Interval (REI) is 24 hours. For Non-ULV applications: the maximum
application rate is 1.25 pounds active ingredient per acre; the maximum number of applications per year
is 3; and the minimum retreatment interval is 5 days.
Kohlrabi: The Restricted-Entry Interval (REI) is 24 hours. For Non-ULV applications: the maximum
application rate is 1.25 pounds active ingredient per acre; the maximum number of applications per year
is 2; and the minimum retreatment interval is 7 days.
Kumquat: The Restricted-Entry Interval (REI) is 48 hours. For Non-ULV applications: the maximum
application rate is 4.5 pounds active ingredient per acre; the maximum number of applications per year is
1. For ULV applications: the maximum application rate is 0.175 pounds active ingredient per acre; the
maximum number of applications per year is 2; and the minimum retreatment interval is 7 days.
Leeks: The Restricted-Entry Interval (REI) is 24 hours. For Non-ULV applications: the maximum
application rate is 1.56 pounds active ingredient per acre; the maximum number of applications per year
is 2; and the minimum retreatment interval is 7 days.
Lemon (California only): The Restricted-Entry Interval (REI) is 72 hours. For Non-ULV applications:
the maximum application rate is 7.5 pounds active ingredient per acre; the maximum number of
applications per year is 1. For ULV applications: the maximum application rate is 0.175 pounds active
ingredient per acre; the maximum number of applications per year is 3; and the minimum retreatment
interval is 7 days.
Lemons (Florida only): The Restricted-Entry Interval (REI) is 48 hours. For Non-ULV applications: the
maximum application rate is 1.25 pounds active ingredient per acre; the maximum number of
applications per year is 1. For ULV applications: the maximum application rate is 0.175 pounds active
ingredient per acre; the maximum number of applications per year is 3; and the minimum retreatment
interval is 7 days.
Lespedeza: The Restricted-Entry Interval (REI) is 12 hours. For Non-ULV applications: the maximum
application rate is 4.5 pounds active ingredient per acre; the maximum number of applications per year is
1. For ULV applications: the maximum application rate is 0.175 pounds active ingredient per acre; the
maximum number of applications per year is 2; and the minimum retreatment interval is 7 days.
Lettuce, head: The Restricted-Entry Interval (REI) is 24 hours. For Non-ULV applications: the
maximum application rate is 1.88 pounds active ingredient per acre; the maximum number of
applications per year is 2; and the minimum retreatment interval is 6 days.
Lettuce, leaf: The Restricted-Entry Interval (REI) is 24 hours. For Non-ULV applications: the maximum
application rate is 1.88 pounds active ingredient per acre; the maximum number of applications per year
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is 2; and the minimum retreatment interval is 5 days.
Limes (California only): The Restricted-Entry Interval (REI) is 72 hours. For Non-ULV applications:
the maximum application rate is 7.5 pounds active ingredient per acre; the maximum number of
applications per year is 1. For ULV applications: the maximum application rate is 0.175 pounds active
ingredient per acre; the maximum number of applications per year is 3; and the minimum retreatment
interval is 7 days.
Limes (U.S., except California): The Restricted-Entry Interval (REI) is 48 hours. For Non-ULV
applications: the maximum application rate is 4.5 pounds active ingredient per acre; the maximum
number of applications per year is 2; and the minimum retreatment interval is 30 days. For ULV
applications: the maximum application rate is 0.175 pounds active ingredient per acre; the maximum
number of applications per year is 3; and the minimum retreatment interval is 7 days.
Loganberry: The Restricted-Entry Interval (REI) is 12 hours. For Non-ULV applications: the maximum
application rate is 2.0 pounds active ingredient per acre; the maximum number of applications per year is
2; and the minimum retreatment interval is 7 days.
Lupine, seed: The Restricted-Entry Interval (REI) is 12 hours. For ULV applications: the maximum
application rate is 0.61 pounds active ingredient per acre; the maximum number of applications per year
isl.
Macadamia Nut: The Restricted-Entry Interval (REI) is 12 hours. For Non-ULV applications: the
maximum application rate is 0.94 pounds active ingredient per acre; the maximum number of
applications per year is 2; and the minimum retreatment interval is 7 days.
Mushrooms: The Restricted-Entry Interval (REI) is 12 hours. The maximum application rate is 1.7
pounds active ingredient per acre; the maximum number of applications per year is 4; and the minimum
retreatment interval is 3 days.
Mustard greens: The Restricted-Entry Interval (REI) is 24 hours. For Non-ULV applications: the
maximum application rate is 1.25 pounds active ingredient per acre; the maximum number of
applications per year is 3; and the minimum retreatment interval is 5 days.
Nectarines: The Restricted-Entry Interval (REI) is 24 hours. For Non-ULV applications: the maximum
application rate is 3.0 pounds active ingredient per acre; the maximum number of applications per year is
3; and the minimum retreatment interval is 7 days.
Oats: For Non-ULV applications: the maximum application rate is 1.0 pounds active ingredient per acre;
the maximum number of applications per year is 2; and the minimum retreatment interval is 7 days. For
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ULV applications: the maximum application rate is 0.61 pounds active ingredient per acre; the maximum
number of applications per year is 2; and the minimum retreatment interval is 7 days.
Okra: The Restricted-Entry Interval (REI) is 12 hours. ForNon-ULV applications: the maximum
application rate is 1.2 pounds active ingredient per acre; the maximum number of applications per year is
5; and the minimum retreatment interval is 7 days.
Onions (bulb and green): The Restricted-Entry Interval (REI) is 12 hours. For Non-ULV applications:
the maximum application rate is 1.56 pounds active ingredient per acre; the maximum number of
applications per year is 2; and the minimum retreatment interval is 7 days.
Oranges (California only): The Restricted-Entry Interval (REI) is 72 hours. For Non-ULV applications:
the maximum application rate is 7.5 pounds active ingredient per acre; the maximum number of
applications per year is 1. For ULV applications: the maximum application rate is 0.175 pounds active
ingredient per acre; the maximum number of applications per year is 3; and the minimum retreatment
interval is 7 days.
Oranges (U.S., except California): The Restricted-Entry Interval (REI) is 48 hours. For Non-ULV
applications: the maximum application rate is 4.5 pounds active ingredient per acre; the maximum
number of applications per year is 1. For ULV applications: the maximum application rate is 0.175
pounds active ingredient per acre; the maximum number of applications per year is 3; and the minimum
retreatment interval is 7 days.
Papaya: The Restricted-Entry Interval (REI) is 12 hours. For Non-ULV applications: the maximum
application rate is 1.25 pounds active ingredient per acre; the maximum number of applications per year
is 4; and the minimum retreatment interval is 3 days.
Parsley: The Restricted-Entry Interval (REI) is 24 hours. For Non-ULV applications: the maximum
application rate is 1.5 pounds active ingredient per acre; the maximum number of applications per year is
2; and the minimum retreatment interval is 7 days.
Parsnip: The Restricted-Entry Interval (REI) is 24 hours. For Non-ULV applications: the maximum
application rate is 1.25 pounds active ingredient per acre; the maximum number of applications per year
is 3; and the minimum retreatment interval is 7 days.
Passion fruit: The Restricted-Entry Interval (REI) is 12 hours. For Non-ULV applications: the maximum
application rate is 1.0 pounds active ingredient per acre; the maximum number of applications per year is
8; and the minimum retreatment interval is 7 days.
Peach: The Restricted-Entry Interval (REI) is 24 hours. For Non-ULV applications: the maximum
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application rate is 3.0 pounds active ingredient per acre; the maximum number of applications per year is
3; and the minimum retreatment interval is 11 days.
Pears: The Restricted-Entry Interval (REI) is 12 hours. For Non-ULV applications: the maximum
application rate is 1.25 pounds active ingredient per acre; the maximum number of applications per year
is 2; and the minimum retreatment interval is 7 days.
Peas (succulent): The Restricted-Entry Interval (REI) is 12 hours. For Non-ULV applications: the
maximum application rate is 1.0 pounds active ingredient per acre; the maximum number of applications
per year is 2; and the minimum retreatment interval is 7 days.
Pecans: The Restricted-Entry Interval (REI) is 24 hours. For Non-ULV applications: the maximum
application rate is 2.5 pounds active ingredient per acre; the maximum number of applications per year is
2; and the minimum retreatment interval is 7 days.
Peppers: The Restricted-Entry Interval (REI) is 12 hours. For Non-ULV applications: the maximum
application rate is 1.56 pounds active ingredient per acre; the maximum number of applications per year
is 2; and the minimum retreatment interval is 5 days.
Pineapple: The Restricted-Entry Interval (REI) is 24 hours. For Non-ULV applications: the maximum
application rate is 2.0 pounds active ingredient per acre; the maximum number of applications per year is
3; and the minimum retreatment interval is 7 days.
Pumpkin: The Restricted-Entry Interval (REI) is 12 hours. For Non-ULV applications: the maximum
application rate is 1.0 pounds active ingredient per acre; the maximum number of applications per year is
2; and the minimum retreatment interval is 7 days.
Radish: The Restricted-Entry Interval (REI) is 24 hours. For Non-ULV applications: the maximum
application rate is 1.25 pounds active ingredient per acre; the maximum number of applications per year
is 3; and the minimum retreatment interval is 7 days.
Raspberry: The Restricted-Entry Interval (REI) is 12 hours. For Non-ULV applications: the maximum
application rate is 2.0 pounds active ingredient per acre; the maximum number of applications per year is
2; and the minimum retreatment interval is 7 days.
Rice: The Restricted-Entry Interval (REI) is 12 hours. For Non-ULV applications: the maximum
application rate is 1.25 pounds active ingredient per acre; the maximum number of applications per year
is 2; and the minimum retreatment interval is 7 days. For ULV applications: the maximum application
rate is 0.61 pounds active ingredient per acre; the maximum number of applications per year is 2; and the
minimum retreatment interval is 7 days.
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Rutabagas: The Restricted-Entry Interval (REI) is 24 hours. For Non-ULV applications: the maximum
application rate is 1.25 pounds active ingredient per acre; the maximum number of applications per year
is 3; and the minimum retreatment interval is 7 days.
Rye: The Restricted-Entry Interval (REI) is 12 hours. For Non-ULV applications: the maximum
application rate is 1.00 pounds active ingredient per acre; the maximum number of applications per year
is 2; and the minimum retreatment interval is 7 days. For ULV applications: the maximum application
rate is 0.61 pounds active ingredient per acre; the maximum number of applications per year is 1
Salsify (including tops): The Restricted-Entry Interval (REI) is 24 hours. For Non-ULV applications: the
maximum application rate is 1.25 pounds active ingredient per acre; the maximum number of
applications per year is 3; and the minimum retreatment interval is 7 days.
Shallots: The Restricted-Entry Interval (REI) is 24 hours. For Non-ULV applications: the maximum
application rate is 1.56 pounds active ingredient per acre; the maximum number of applications per year
is 2; and the minimum retreatment interval is 7 days.
Sorghum: The Restricted-Entry Interval (REI) is 12 hours. For ULV applications: the maximum
application rate is 0.61 pounds active ingredient per acre; the maximum number of applications per year
is 2; and the minimum retreatment interval is 7 days.
Spinach: The Restricted-Entry Interval (REI) is 24 hours. For Non-ULV applications: the maximum
application rate is 2.0 pounds active ingredient per acre; the maximum number of applications per year is
2; and the minimum retreatment interval is 7 days.
Squash, summer: The Restricted-Entry Interval (REI) is 24 hours. . For Non-ULV applications: the
maximum application rate is 1.750 pounds active ingredient per acre; the maximum number of
applications per year is 3; and the minimum retreatment interval is 7 days.
Squash, winter: The Restricted-Entry Interval (REI) is 12 hours. For Non-ULV applications: the
maximum application rate is 1.0 pounds active ingredient per acre; the maximum number of applications
per year is 3; and the minimum retreatment interval is 7 days.
Strawberry: The Restricted-Entry Interval (REI) is 12 hours. For Non-ULV applications: the maximum
application rate is 2.0 pounds active ingredient per acre; the maximum number of applications per year is
4; and the minimum retreatment interval is 7 days.
Swiss Chard: The Restricted-Entry Interval (REI) is 24 hours. The maximum application rate is 1.5
pounds active ingredient per acre; the maximum number of applications per year is 2; and the minimum
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retreatment interval is 7 days.
Tangerine (California only): The Restricted-Entry Interval (REI) is 72 hours. For Non-ULV
applications: the maximum application rate is 7.5 pounds active ingredient per acre; the maximum
number of applications per year is 1. For ULV applications: the maximum application rate is 0.175
pounds active ingredient per acre; the maximum number of applications per year is 3; and the minimum
retreatment interval is 7 days.
Tangerine (U.S., except California): The Restricted-Entry Interval (REI) is 48 hours. For Non-ULV
applications: the maximum application rate is 4.5 pounds active ingredient per acre; the maximum
number of applications per year is 1. For ULV applications: the maximum application rate is 0.175
pounds active ingredient per acre; the maximum number of applications per year is 3; and the minimum
retreatment interval is 7 days.
Tangelos (California only): The Restricted-Entry Interval (REI) is 72 hours. For Non-ULV
applications: the maximum application rate is 7.5 pounds active ingredient per acre; the maximum
number of applications per year is 1. For ULV applications: the maximum application rate is 0.175
pounds active ingredient per acre; the maximum number of applications per year is 3; and the minimum
retreatment interval is 7 days.
Tangelos (U.S., except California): The Restricted-Entry Interval (REI) is 48 hours. For Non-ULV
applications: the maximum application rate is 4.5 pounds active ingredient per acre; the maximum
number of applications per year is 1. For ULV applications: the maximum application rate is 0.175
pounds active ingredient per acre; the maximum number of applications per year is 3; and the minimum
retreatment interval is 7 days.
Tomatoes: The Restricted-Entry Interval (REI) is 12 hours. For Non-ULV applications: the maximum
application rate is 1.56 pounds active ingredient per acre; the maximum number of applications per year
is 4; and the minimum retreatment interval is 5 days.
Tomatilloes: The Restricted-Entry Interval (REI) is 12 hours. For Non-ULV applications: the maximum
application rate is 1.56 pounds active ingredient per acre; the maximum number of applications per year
is 4; and the minimum retreatment interval is 5 days.
Trefoil, birdsfoot: The Restricted-Entry Interval (REI) is 12 hours. For Non-ULV applications: the
maximum application rate is 1.56 pounds active ingredient per acre; the maximum number of
applications per year is 5; and the minimum retreatment interval is 14 days. For ULV applications: the
maximum application rate is 0.61 pounds active ingredient per acre; the maximum number of
applications per year is 2; and the minimum retreatment interval is 14 days.
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Turnip (greens): The Restricted-Entry Interval (REI) is 24 hours. For Non-ULV applications: the
maximum application rate is 1.25 pounds active ingredient per acre; the maximum number of
applications per year is 3; and the minimum retreatment interval is 5 days.
Turnip (roots): The Restricted-Entry Interval (REI) is 24 hours. For Non-ULV applications: the
maximum application rate is 1.25 pounds active ingredient per acre; the maximum number of
applications per year is 3; and the minimum retreatment interval is 7 days.
Vegetables, leafy, Brassica (Cole) are listed above, and include: broccoli, Chinese broccoli, broccoli raab;
Brussels sprouts; cabbage; Chinese cabbage; cauliflower; collards; kale; and mustard greens.
Vegetables, leafy (except Brassica) are listed above and include: celery; dandelion; endive; lettuce (head,
and leaf).
Parsley: The Restricted-Entry Interval (REI) is 24 hours. For Non-ULV applications: the maximum
application rate is 1.5 pounds active ingredient per acre; the maximum number of applications per year is
2; and the minimum retreatment interval is 7 days.
Spinach: The Restricted-Entry Interval (REI) is 24 hours. For Non-ULV applications: the maximum
application rate is 2.0 pounds active ingredient per acre; the maximum number of applications per year is
2; and the minimum retreatment interval is 7 days.
Swiss chard: The Restricted-Entry Interval (REI) is 24 hours. For Non-ULV applications: the maximum
application rate is 1.5 pounds active ingredient per acre; the maximum number of applications per year is
2; and the minimum retreatment interval is 7 days.
Walnut: The Restricted-Entry Interval (REI) is 12 hours. For Non-ULV applications: the maximum
application rate is 2.5 pounds active ingredient per acre; the maximum number of applications per year is
3; and the minimum retreatment interval is 7 days.
Watermelon: The Restricted-Entry Interval (REI) is 12 hours. For Non-ULV applications: the maximum
application rate is 1.5 pounds active ingredient per acre; the maximum number of applications per year is
4; and the minimum retreatment interval is 7 days.
Wheat (spring and summer): The Restricted-Entry Interval (REI) is 12 hours. For Non-ULV
applications: the maximum application rate is 1.0 pounds active ingredient per acre; the maximum
number of applications per year is 2; and the minimum retreatment interval is 7 days. For ULV
applications: the maximum application rate is 0.61 pounds active ingredient per acre; the maximum
number of applications per year is 2; and the minimum retreatment interval is 7 days.
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Wild Rice: The Restricted-Entry Interval (REI) is 12 hours. For Non-ULV applications: the maximum
application rate is 1.25 pounds active ingredient per acre; the maximum number of applications per year
is 2; and the minimum retreatment interval is 7 days. For ULV applications: the maximum application
rate is 0.61 pounds active ingredient per acre; the maximum number of applications per year is 2; and the
minimum retreatment interval is 7 days.
Yams: The Restricted-Entry Interval (REI) is 12 hours. For Non-ULV applications: the maximum
application rate is 1.56 pounds active ingredient per acre; the maximum number of applications per year
is 2; and the minimum retreatment interval is 7 days.
End Use Products Intended Primarily for Use by Homeowners
Environmental Hazards
"ENVIRONMENTAL HAZARDS"
"This product is toxic to fish. Do not apply directly to water. Do not contaminate water when disposing
of equipment washwaters or rinsate."
"Do not apply when weather conditions favor drift from treated areas. Drift and runoff from treated areas
may be hazardous to organisms in neighboring areas."
Precautionary Statements
Application Restrictions
All products:
"Do not apply this product in a way that will contact any person or pet, either directly or through drift.
Keep people and pets out of the area during application."
Directions for Use under
General Precautions and
Restrictions
Statements must be in the
color red and in all caps.
Entry Restrictions
Products Applied as a Liquid:
"Do not allow people or pets to enter the treated area until sprays have dried."
When applied as a fogger, do not enter treated area until vapors, mists, and aerosols have dispersed, and
the treated area has been thoroughly ventilated
Directions for Use under
General Precautions and
Restrictions
Other Application
Restrictions (Risk
Mitigation)
All Products/Formulations Containing Malathion
Delete all directions for use for the following use-patterns:
• all direct animal and livestock treatments including (goats, hog, horse, poultry, fowl, sheep
and cattle: dairy, non-dairy, lactating and non-lactating)
Directions for Use
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• animal kennels/sleeping quarters (commercial)
• animal premise and barns used for dairy and livestock
• stables and pens
• poultry houses
• animal kennels/sleeping quarters
• cattle feedlots and holding pens
• feed rooms
• cattle feed concentrate blocks (non-medicated)
• dogs and cats
• pet food and pest stuffs
• cereal processing plants
• packaged cereals
• commercial and industrial uses for bagged flour
• commercial shipping containers -feed/food- empty
• commercial storages/ warehouses premises
• commercial transportation facilities -feed/food -empty
• commercial transportation facilities -nonfeed/nonfood
• commercial/institutional/industrial premises/equipment (indoor)
• commercial/institutional/industrial premises/equipment (outdoor)
• dairies/cheese processing plant equipment (food contact)
• edible and inedible commercial establishments
• edible and inedible eating establishments
• edible and inedible food processing plants
• field or garden seeds
• forest trees
• rabbits on wire
• golf course turf
• greenhouse - empty, or in-use
• human clothing (woolens and other fabrics)
• manure piles
• mattresses
• quince
• residential lawns (broadcast)
• sewage systems
• lentils
• tobacco
125
-------
1 PPE that is established on the basis of Acute Toxicity of the end-use product must be compared to the active ingredient PPE in this document. The more
protective PPE must be placed in the product labeling. For guidance on which PPE is considered more protective, see PR Notice 93-7.
2 The registrant must drop the N type filter from the respirator statement if the pesticide product contains or is used with oil.
Instructions in the Labeling section appearing in quotations represent the exact language that should appear on the label.
Instructions in the Labeling section not in quotes represents actions that the registrant should take to amend their labels or product registrations.
126
-------
Appendix A
List of Malathion Use Sites and Application Rates
Crop
Alfalfa
Apricot
Asparagus
Avocado
Barley
Beans, dry, snap,
Lima
Beets, garden
Blueberry (high bush
and low bush)
Broccoli, Chinese
Broccoli, Broccoli
rabb
Brussels sprouts
Cabbage
Application Type,
Application Method
(Formulation1)
Foliar
Ground/aerial
Foliar
Ground
Foliar
Ground/aerial
Foliar
ground
Foliar
Ground/aerial
Foliar
Aerial
Non-ULV
ULV/RTU
ULV only
Foliar
Ground
Foliar
Ground
Non ULV
ULV/RTU
Foliar
Ground/aerial
Foliar
Ground/aerial
Foliar
Maximum
Single
Application
Rate
(Ib ai/A)
1.25
1.5
1.25
4.7
1.25
0.61
0.61
1.25
1.25
0.77
1.25
1.25
1.25
Maximum
Number of
Applications
Per Year
2 per cutting
2
2
2
2
2
2
3
3
3
1
1
6
Minimum
Application
Interval
(days)
14
7
7
30
7
7
7
7
7
10
7
7
7
Minimum
Pre- Harvest
Interval
(days)
0
6
1
7
7
7
1
7
1
1
2
2
7
Restricted Entry
Interval (days)
12 hr
12hrs
12hrs
2 days
12hrs
12hrs
12hrs
12hrs
12hrs
2 days
2 days
2 days
127
-------
Crop
Cantaloupe
Caneberries
(blackberry,
boysenberry,
dewberry,
loganberry,
raspberry)
Carrots
Cucumber
Cauliflower
Celery
Cherries, sweet
Cherries, tart
Citrus Fruits
(grapefruit, lemon,
lime, organge,
tangerine, tangelo)
Application Type,
Application Method
(Formulation1)
Ground/aerial
Foliar
Ground/aerial
Foliar
ground
Foliar
Ground/aerial
Foliar
Ground/aerial
Foliar
Ground/aerial
Foliar
Ground/aerial
Foliar
Ground/
Aerial
Foliar
Ground/
Aerial
Foliar
Ground/
aerial
Non-ULV
ULV/RTU
Non-ULV
ULV/RTU
Non-ULV
Maximum
Single
Application
Rate
(Ib ai/A)
1.0
2.0
1.25
1.75
1.25
1.5
1.75
1.22
1.75
1.22
All states other
than CA:
4.5
or
1.5
r"A nnKr.
Maximum
Number of
Applications
Per Year
2
3
2
2
1
2
4
4
4
6
1
3
Minimum
Application
Interval
(days)
7
7
7
7
7
7
3
7
3
7
NA
30
Minimum
Pre-Harvest
Interval
(days)
1
1
7
1
2
7
3
1
1
7
Restricted Entry
Interval (days)
12hrs
12hrs
24hrs
24hrs
2 days
24hrs
12hrs
12hrs
3 days
128
-------
Crop
Clover
Collards
Corn, field
Corn, sweet, and pop
Chayote fruit
Chayote root
Chestnut
Chinese greens
(Chinese cabbage)
Clover
Application Type,
Application Method
(Formulation1)
Foliar
Ground/
aerial
ULV/ RTU
Non-ULV
ULV/RTU
Foliar
Ground/aerial
Foliar
Ground/
aerial
Foliar
Ground/
aerial
Non-ULV
ULV/RTU
Non-ULV
ULV/RTU
Foliar
Ground/aerial
Foliar
Ground
Foliar
Ground
Foliar
Ground/aerial
Foliar
Maximum
Single
Application
Rate
(Ib ai/A)
7.5
or
1.5
0.175
1.25
0.61
1.25
1.0
0.61
1.0
0.61
1.75
1.56
2.5
1.25
1.25
Maximum
Number of
Applications
Per Year
1
3
3
2 per cutting
2 per cutting
3
2
2
2
2
2
2
3
2
2 per cutting
Minimum
Application
Interval
(days)
NA
30
7
14
14
7
7
7
5
5
7
7
7
7
14
Minimum
Pre-Harvest
Interval
(days)
7
0
0
7
7
7
5
5
1
0
2
7
0
Restricted Entry
Interval (days)
12hrs
12hrs
24hrs
3 days for
detasseling
12 hrs for all other
activites
3 days for
detasseling
12 hrs for all other
activities
24 hrs
24 hrs
24 hrs
24 hrs
12 hrs
129
-------
Crop
Cotton (non boll
weevil treatment use)
Currant
Dandelion
Dates
Eggplant
Eggplant, oriental
Endive (escarole)
Fig
Flax
Garlic
Grains, stored
(barley, corn, oats,
rye, wheat)
Grapes, raisin, table,
wine
Application Type,
Application Method
(Formulation1)
Ground/aerial
Foliar Non-ULV
Ground/aerial ULV/RTU
Foliar
Ground/aerial
Foliar
Ground/aerial
Dust
Foliar
Ground/aerial
Foliar
Ground/aerial
Foliar
Ground/aerial
Foliar
Ground
Foliar
Ground
Foliar
Ground/aerial
Surface treatment
Foliar
Ground
Root dip
Maximum
Single
Application
Rate
(Ib ai/A)
2.5
1.22
1.25
1.25
4.25
1.56
1.56
1.25
2.0
0.5
1.56
Loading:
0.624 Ib ai/1000
bushels
Storage:
0.3121bai/100
bushels
1.88
Maximum
Number of
Applications
Per Year
3
3
3
2
5
4
5
2
2
3
3
3 per storage
period
2
Minimum
Application
Interval
(days)
7
7
7
7
7
5
5
7
5
7
7
60
14
Minimum
Pre-Harvest
Interval
(days)
7
7
1
7
21
3
3
7
5
52
3
NA
3
Restricted Entry
Interval (days)
2 days
12hrs
24hrs
2 days
12hrs
12hrs
24hrs
24hrs
12hrs
24hrs
12hrs
3 days for girdling
and tying;
24 hrs for all other
130
-------
Crop
Grass, forage, hay
Grasses, Bermuda,
Guava
Hops
Horseradish
Kale
Kohlrabi
Kumquats
Leeks
Lespedeza
Lettuce, head
Lettuce, leaf
Lupine
Application Type,
Application Method
(Formulation1)
Foliar
Ground/aerial
Foliar Non-ULV
Gr07d/ ULV/RTU
aerial
Foliar
Ground
Foliar
Ground/aerial
Foliar
Ground/aerial
Foliar
Ground/aerial
Foliar
Ground/aerial
Foliar Non-ULV
Ground ULV/RTU
Foliar
Ground/aerial
Foliar Non-ULV
Ground/ ULV/RTU
aerial
Foliar
Ground/aerial
Foliar
Ground/aerial
Foliar TTTW i
^ , , ULV only
Ground/ J
Maximum
Single
Application
Rate
(Ib ai/A)
1.25
1.25
0.92
1.25
0.63
1.25
1.25
1.25
4.5
0.175
1.56
1.25
0.61
1.88
1.88
0.61
Maximum
Number of
Applications
Per Year
1
1 per cutting
13
3
3
3
2
1
2
2
2 per cutting
2
2
1
Minimum
Application
Interval
(days)
NA
NA
3
7
7
5
7
30
7
7
14
6
5
NA
Minimum
Pre-Harvest
Interval
(days)
0
0
2
10
7
7
7
7
1
3
0
14
14
1
Restricted Entry
Interval (days)
activities
12hrs
12hrs
12hrs
12hrs
24hrs
24hrs
24hrs
2 days
12hrs
24hrs
12hrs
24hrs
24hrs
12hrs
131
-------
Crop
Turnips
Macadamia nut
Mango
Melons (other than
watermelon)
Mint
Mushrooms
Mustard greens
Nectarines
Oats
Okra
Onions, bulb, and
green
Papaya
Parsley
Application Type,
Application Method
(Formulation1)
Aerial
Foliar
Ground/aerial
Foliar
Ground
Foliar
Ground
Foliar
Ground/aerial
Foliar
Ground/aerial
Foliar
Foliar
Ground/aerial
Foliar
Ground
Foliar Non-ULV
Ground/ ULV/RTU
aerial
Foliar
Ground/aerial
Foliar
Ground/aerial
Foliar
Ground
Foliar
Maximum
Single
Application
Rate
(Ib ai/A)
1.25
0.94
1.25
1.0
0.94
1.7
1.25
3.0
1.0
0.61
1.2
1.56
1.25
1.5
Maximum
Number of
Applications
Per Year
3
2
8
2
3
4
3
3
2
2
5
2
4
2
Minimum
Application
Interval
(days)
5 day for turnip
greens
7 day for turnip
root
7
7
7
7
3
5
7
7
7
7
7
3
7
Minimum
Pre-Harvest
Interval
(days)
7
1
1
1
7
1
7
7
7
7
1
3
1
2
Restricted Entry
Interval (days)
24hrs
12hrs
12hrs
12hrs
12hrs
12hrs
24hrs
24hrs
12hrs
12hrs
12hrs
12hrs
12hrs
24hrs
132
-------
Crop
Parsnip
Passion fruit
Pasture and rangeland
Peaches
Pears
Peas, dried
Peas, green
Pecans
Peppers
Pineapple
Potatoes
Pumpkins
Radish
Rutabagas
Application Type,
Application Method
(Formulation1)
Ground/aerial
Foliar
Ground/aerial
Foliar
Ground
Foliar
Ground/
aerial
Foliar
Ground
ULV only
Foliar
Ground
Foliar
Ground
Foliar
Ground/aerial
Foliar
Ground
Foliar
Ground/aerial
Foliar
Ground
Foliar
Ground/aerial
Foliar
Ground/aerial
Foliar
Ground/aerial
Foliar
Maximum
Single
Application
Rate
(Ib ai/A)
1.25
1.0
0.9375
3.0
1.25
1.0
1.0
2.5
1.56
2.0
1.56
1.0
1.25
1.25
Maximum
Number of
Applications
Per Year
3
8
2
3
2
2
2
2
2
3
2
2
3
3
Minimum
Application
Interval
(days)
7
7
7
11
7
7
7
7
5
7
7
7
7
7
Minimum
Pre-Harvest
Interval
(days)
7
3
1
7
1
3
3
7
3
7
0
1
7
7
Restricted Entry
Interval (days)
24hrs
12hrs
12
24hrs
12hrs
12hrs
12hrs
24hrs
12hrs
24hrs
12hrs
12hrs
24hrs
24hrs
133
-------
Crop
Rice
Rye
Salsify
Shallot
Sorghum
Spinach
Squash, summer
Squash, winter
Strawberry
Sweet potatoes
Swiss chard
Tomatoes,
Tomatilloes
Vetch
Application Type,
Application Method
(Formulation1)
Ground/aerial
Foliar Non-ULV
Gr°7d/ ULV/RTU
aerial
Foliar Non-ULV
Gr°Uf ' ULV/RTU
Aerial
Foliar
Ground/aerial
Foliar
Ground/aerial
Foliar
Ground/ ULV only
aerial
Foliar
Ground/aerial
Foliar
Ground/aerial
Foliar
Ground/aerial
Foliar
Ground/aerial
Foliar
Ground/aerial
Foliar
Ground/aerial
Foliar
Ground/aerial
Foliar Non-ULV
Gr°7d/ ULV/RTU
aerial
Maximum
Single
Application
Rate
(Ib ai/A)
1.25
0.61
1.0
0.61
1.25
1.56
0.61
2.0
1.75
1.0
2.0
1.56
1.5
1.56
1.56
0.61
Maximum
Number of
Applications
Per Year
2
2
3
1
3
2
2
2
3
3
4
2
2
4
5
2 per cutting
Minimum
Application
Interval
(days)
7
7
7
NA
7
7
7
7
7
7
7
7
7
5
14
14
Minimum
Pre-Harvest
Interval
(days)
7
14
7
7
7
3
7
7
1
1
3
0
14
1
3
0
Restricted Entry
Interval (days)
12hrs
12hrs
24hrs
24hrs
12hrs
24hrs
24hrs
12hrs
12hrs
12hrs
24hrs
12hrs
12hrs
134
-------
Crop
Walnuts
Watercress
Watermelons
Wheat, spring and
winter
Wild Rice
Yams
Application Type,
Application Method
(Formulation1)
Foliar
Ground
Foliar
Ground/aerial
Foliar
Ground
Foliar
Ground/
aerial
Foliar
Ground/
aerial
Non-ULV
ULV/RTU
Non-ULV
ULV/RTU
Foliar
Ground/aerial
Maximum
Single
Application
Rate
(Ib ai/A)
2.5
1.25
1.5
1.0
0.61
1.25
0.61
1.56
Maximum
Number of
Applications
Per Year
3
5
4
2
2
2
2
2
Minimum
Application
Interval
(days)
7
3
7
7
7
7
7
7
Minimum
Pre-Harvest
Interval
(days)
7
3
1
7
7
7
14
0
Restricted Entry
Interval (days)
24hrs
24hrs
12hrs
12hrs
12hrs
24hrs
12hrs
24hrs
135
-------
Non-Agricultural Use Sites
Site
Agricultural, uncultivated
areas
Christmas tree plantations
Cull piles
Drainage systems
Fence rows/hedge rows
Grain/cereal/flour bins
(empty)
Grain/cereal/flour elevators
(empty)
Greenhouse (empty)
Household/domestic
dwellings (perimeter
outdoor only)
Intermittently flooded areas
Non-agricultural outdoor
building structures
Non-agricultural rights-of-
way/fencerows
Non-agricultural
uncultivated areas/soil
Ornamental and/or shade
trees
Ornamental herbaceous
plants
Ornamental non-flowering
plants
Ornamental woody shrubs
and vines
Pine seed orchards
Form
Non-ULV
ULV
Non-ULV
ULV
Non-ULV
Non-ULV
Non-ULV
Non-ULV
Non-ULV
Non-ULV
Non-ULV
Non-ULV
Non-ULV
Non-ULV
ULV
Non-ULV
ULV
Non-ULV
ULV
Non-ULV
Non-ULV
Non-ULV
Non-ULV
Non-ULV
Maximum Single
Application Rate
1.0
0.1875
3.2
0.9375
6.857
0.625
0.2439
0.4762
5
0.4762
5
0.0434
0.2439
0.5078
0.232
0.2057
0.9281
0.6
0.9281
2.5
2.5
2.5
2.5
0.9375
Unit
Lb ai/A
Lb ai/A
Lb/1000 ft2
Lb/2.5 gal
Lb/1000 ft2
Lb/1000 ft2
Lb/25 gal
Lb/1000 ft2
Lb/25 gal
Lb/1000 ft2
Lb/1000 ft2
Lb ai/A
Lb ai/A
Lb/1000 ft2
Lb ai/A
Lb ai/A
Lb/lOOgal
Lb/ 100 gal
Lb/lOOgal
Lb/lOOgal
Lb ai/A
Use Pattern Limitations
Maximum of 2 applications per
year.
12 hr restricted reentry interval
Drench
Contact or surface treatment
Contact or surface treatment
Apply as needed,
7 day minimum retreatment
interval
Soil treatment by sprayer
Application is limited to the
structure base and a 2 ft wide
swath from the structure base.
Maximum of 2 applications per
year.
10 day minimum retreatment
interval.
12 hr restricted reentry interval
12 hr restricted reentry interval
Maximum of 2 applications per
year/growing cycle.
10 day minimum re-treatment
interval.
12 hr restricted reentry interval.
Maximum of 2 applications per
136
-------
Non-Agricultural Use Sites
Site
Refuse/solid waste
containers (outdoors)
Refuse/solid waste sites
(outdoors)
Swamps/marshes/stagnant
water
Wide Area - Public Health
Use
Form
ULV
Non-ULV
Non-ULV
Non-ULV
ULV
Maximum Single
Application Rate
0.9375
0.2439
0.2439
0.5075
0.23
Unit
Lb/1000 ft2
Lb/1000 ft2
Lb ai/A
Lb ai/A
Use Pattern Limitations
year/growing season.
7 day minimum re-treatment
interval.
12 hr restricted reentry interval
Label must comply with PR-
Notice 2005-1, and additional
requirements outlined in the
Label Table.
1: Not all formulations are supported by data, only those formulations supported by data will elegible for
reregistration.
137
-------
Appendix B
Data Supporting Guideline Requirements for the Reregistration of Malathion
Appendix B contains listing of data requirements which support the reregi strati on for
active ingredients within the case malathion covered by this RED. It contains generic data
requirements that apply to all malathion 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. The data requirements are listed by Guideline Number.
The Guideline Numbers accompanying each test refer to the test protocols set in the
Pesticide Assessment Guidance available from the National Technical Information
Service, 5285 Port Royal Road, Springfield, VA 22161 (703) 487-4650.
2. Use Pattern. 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 H. Greenhouse Food
B. Terrestrial Feed I. Greenhouse Non-Food
C. Terrestrial Non-Food J. Forestry
D. Aquatic Food K. Residential
E. Aquatic Non-Food Outdoor L. Indoor Food
F. Aquatic Non-Food Industrial M. Indoor Non-Food
G. Aquatic Non-Food Residential N. Indoor Medical
O. Indoor Residential
3. Bibliographic Citation. 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 (MRID) 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.
138
-------
New
Guideline
Number
860.1200
830.7000
830.7300
830.7550
830.7840
830.7860
830.7200
830.7300
830.7950
835.2120
835.2240
835.2410
835.
835.4100
835.4400
835.
835.1240
835.1410
835.1100
835.1200
850.2100
850.2100
850.2100
165-3
Old
Guideline
Number
63-12
63-10
63-11
63-8
63-8
63-5
63-7
63-9
161-1
161-2
161-3
161-4
162-1
162-3
162-4
163-1
163-2
164-1
164-2
165-4
71-l(a)
71-1 (b)
71-1 (b)
Study Description
Directions for Use
PH
Dissociation constant in water
Octanol/water partition coefficient
Water solubility
Solvent solubility
Melting point/melting range
Density
Vapor pressure
Hydrolysis
Direct Aqueous Photolysis
Soil Photolysis
Air Photolysis
Aerobic Soil Metabolism
Anaerobic Aquatic Metabolism
Aerobic Aquatic
Leaching/Adsorption/De sorption
Volatility-lab
Soil Dissipation
Aquatic Dissipation
Irrigated Crop
Fish Accumulation
Acute Avian Oral, LD50 - Quail/Duck
Avian Acute Oral - Quail
(TGAI)
Avian Acute Oral - Mallard Duck (TEP)
Citation/ Data Required
Data Required1
40944103
40966603
40944103
40944106, 40966603, 41 126201
40944106, 40966603, 41 126201
40966603
40944104
40944103,40966603
40941201,43166301
41673001,43166301
40658009, 41695501, 43166301
40969301,43166301
41721701,43166301
42216301,43163301
42271601,43163301
41345201, 43163301, 43868601
42015201
41748901, 41727701, 43042401, 43042402,
43166301
42058401, 42058402, 43166301
42058401, 42058402, 43166301
43106401, 43106402, 43340301
00160000
00022923
00022923
139
-------
New
Guideline
Number
850.2300
850.2300
850.1075
850.1075
850.1075
850.1075
850.1010
850.1010
850.1045
850.1045
850.1045
850.1045
850.1045
850.1045
850.1400
850.1400
850.1300
1850.3020
1850.3020
860.1200
860.1300
860.1300
Old
Guideline
Number
71-4(a)
71-4(b)
72-1 (a)
72-1 (b)
72-l-(c)
72-l-(d)
72-2(a)
72-2(b)
72-3(a)
72-3(b)
72-3(c)
72-3(d)
72-3(e)
72-3(f)
72-4
72-4(a)
72-4(b)
141-1
141-2
171-3
171-4a
171-4a
Study Description
Avian Chronic Reproduction - Quail (TGAI)
Avian Chronic Reproduction - Bobwhite quail
(TGAI)
Freshwater Fish - Bluegill (TGAI)
Freshwater Fish LC50's - Bluegill (TEP)
Freshwater Fish LC50's - Rainbow Trout (TGAI)
Freshwater Fish LC50's - Rainbow Trout(TEP)
Freshwater Invertebrate - Daphnia magna (TGAI)
Freshwater Invertebrate - Daphnia magna (TGAI)
and (TEP)
Estuarine/Marine Fish - Sheepshead Minnow
Estuarine/ Marine Mollusk - Mollusk (TGAI)
Estuarine/ Marine Shrimp -Mysid shrimp (TGAI)
Estuarine/Marine - Fish (TEP)
Estuarine/Marine - Mollusk (TEP)
Estuarine/Marine - Shrimp (TEP)
Freshwater Fish Early Life Stage Toxicity(TGAI)
Estuarine/marine fish early-life stage (TGAI)
Estuarine/marine aquatic invertebrate life-cycle
test
Acute Contact T ,D50 - Honevbee
Honey Bee Residue on Foliage
Directions for Use
Nature of Residue - Plants (Plant Metabolism)
Nature of Residue - Animal (Animal Metabolism)
Citation/ Data Required
43501501
42782101
40098001
Required
40098001
Required
40098001
41029701
41174301
40098001
41474501
41252101
42249901
Required
Required
41422401
41718401
05001991, 001999, 05004151, 05004003
41208001,41284701
Required1
00153985, 40397102, 40397103, 42317401,
42482601, 42538901, 42583401
00108942, 00120105, 40415701, 42581401,
42715401,42744401
140
-------
New
Guideline
Number
860.1340
860.1340
860.1380
860.1400
Old
Guideline
Number
171-4c
171-4c
171-4f
Study Description
Residue Analytical Method - Plant Commodities
Residue Analytical Method - Animal
Commodities
Storage Stability Data- Plant Commodities
Water, Fish, and Irrigated Crops
Citation/ Data Required
00033810, 00034342, 00035014, 00035318,
00035330, 00035870, 00058823, 00080769,
00089237, 00089521, 00096676, 00102376,
00104631, 00108941, 00113099, 00113100,
00113135, 00113137, 00113141, 00113142,
00113143, 00113147, 00113149, 00113150,
00113171, 00113173, 00113186, 00113188,
00113203, 00113205, 00113212, 00113223,
00113229, 00113230, 00122714, 40397104,
42894601,43630301
00058823, 00089256, 00098775, 00108941,
00113116, 00120105, 40397101, 40397105
00048370, 00089256, 00089521, 00089808,
00113137,00113206,43549001,43684801,
43910901
Required2
Magnitude of the Residue
860.1500
860.1500
153-3
153-3
Magnitude of the Residue
Required3
Root and Tuber Vegetables Group
Beet, garden, roots
Carrot
Parsnip
Potato
Radish, roots
Turnip, roots
00113116
00100020, 00159270, 44441601
00100020
00089248,43360401
00100020
44266401
Leaves of Root and Tuber Vegetables Group
Beet, garden, tops
00113116,00113212
141
-------
New
Guideline
Number
Old
Guideline
Number
Study Description
Beet, sugar, tops
Turnip, tops
Onion, bulb and green
Citation/ Data Required
00113188
00089260,44266401
00089248, 43350401, 43383301
Leafy Vegetables (Except Brassica Vegetables) Group
Celery
Endive
Lettuce
Parsley
Spinach
Swiss chard
Data Required
00089247,00113212
00100020
00057674, 00089260, 00100020, 00113143,
00113171, 00120105, 43362501, 43367201
00100020, 00159270
00057674, 00089260, 00113143, 44272401
00100020, 00159270
Brassica (Cole) Leafy Vegetables Group
Broccoli
Cabbage
Cauliflower
Collards
Kale
Kohlrabi
Mustard greens
00089259, 00089260, 44203901
00089260,00113143,44232601
0089260
00100020
00089260
00057674, 00100020
00089260,44271101
Legume Vegetables (Succulent or Dried) Group
Bean (succulent and dry)
Pea (succulent)
Soybean seed and aspirated grain fraction
00089245, 00100020, 00113143, 00113166,
43372701, 43376801, 43417601
00113099, 00113120, 44205901
00145201
Foliage of Legume Vegetables Group
Pea (field) vines and hay
00113099,00113120
142
-------
New
Guideline
Number
Old
Guideline
Number
Study Description
Soybean forage and hay
Eggplant
Pepper
Tomato
Citation/ Data Required
00108941
00089250,00113212
00089250,00113212,43175501
00089250, 00100020, 00113143, 00113182,
00113212, 00113214, 00120105, 43372901
Cucurbit Vegetables Group
Cucumber
Melon
Squash
00089249, 00100020, 43370601
00089249, 43107602, 44098401
00100020
Citrus Fruits (Citrus spp. And Fortunella spp.) Group
Grapefruit
Lemon
Tangerine
00089052
00113203
00113182
Pome Fruit Group
Apple
Pear
Quince
Additional Data Required
00057674, 00089258, 43107601, 43107603,
44009601
00089258,44013701
Data Required
Stone Fruits Group
Apricot
Cherry
Peach
00089239,44120001
00035314, 00035870, 00057674, 00089239,
00113143,43108201,43078702
00057674,00113182,44016001
Berries Group
Blackberry
Blueberry
00100020, 00159270, 44282201
00035015, 00089242, 00113165, 00113170,
143
-------
New
Guideline
Number
Old
Guideline
Number
Study Description
Raspberry
Citation/ Data Required
00113176, 00113193, 00113229, 43372601
44282101
Tree Nut Group
Almond, nutmeat and hulls
Chestnut
Macadamia Nut
Walnut
00108941
00116023,44478401
00108941,44076801
00104631, 00120105, 44383301
Cereal Grains Group
Barley grain
Corn (field) grain and aspirated grain fractions
Corn (sweet) K+CWHR
Oat grain
Rice grain
Sorghum grain and aspirated grain fractions
Wheat grain and aspirated grain fractions
Wild rice grain
00089253
00138431, 43468201, 43577401
00057674, 00138431, 43361101
00120105,00153987
43468101
00035013, 00105387, 43360001
43414901,43350402
00113143
Forage, Fodder, and Straw of Cereal Grains Group
Barley hay and straw
Corn (field) forage and stover
Corn (sweet) forage and stover
Oat forage, hay, and straw
Rice straw
Sorghum forage and stover
Wheat forage, hay, and straw
Data Required
43468201
43361101
Data Required
43468101
00035013,00153987
43414901,43350402
Grass Forage, Fodder, and Hay Group
Grass (pasture and rangeland)forage and hay
00089251, 00108941, 43362601
Nongrass Animal Feeds (Forage, Fodder, Straw, and Hay) Group
144
-------
New
Guideline
Number
Old
Guideline
Number
Study Description
Alfalfa forage and hay
Clover forage and hay
Vetch forage and hay
Citation/ Data Required
00035330, 00035886, 00035890, 00089252,
00089521,43546101
00089521,43545201
00034458
Miscellaneous Commodities
Asparagus
Avocado
Cotton, seed and gin by products
Cranberry
Date
Fig
Flax
Grape
Guava
Hops, dried
Mango
Mint (peppermint and spearmint)
Mushroom
Okra
Papaya
Passion fruit
Pineapple
Safflower
Strawberry
00034344, 00120105, 44436101
00113116,43383501
00035318, 00102291, 00102376, 00103342,
00103343, 00108949, 00113097, 00113147,
00113186,43596601
00089242
0089242
00089593, 00120105, 44061201
00113137,43991401
00048370, 00089242, 00101150, 00113095,
001 13205, 001 13206, 43383401
00120105,44391501
00113118
00089254,00113182,44480301
00120105,44124801
00030482, 00120105, 44001 101
00100020, 00108941, 44232701
00108941,44331001
00113182,44472801
00113116,44613801
00113230
00085524, 00089242, 00115967, 43368301,
145
-------
New
Guideline
Number
860.1520
Old
Guideline
Number
153-3
Study Description
Watercress
Citation/ Data Required
44094401
00120105,44094801
Stored Raw Agricultural and Processed Commodities
Almond and nutmeat and hulls
Citrus pulp
Corn grain and aspirated grain fractions
Oats, grain
Peanut nutmeat
Rice grain
Sorghum grain and aspirated grain fractions
Sunflower seeds
Wheat grain and aspirated grain fractions
00104631,00113121,00113134
00113203
00058827, 00058828, 43666801
Data Required
00035130, 00080769, 00089808
00058824
00058828
00096676
00034951, 00058826, 00058828, 00089808,
43661401
Processed Food/Feed
Apple
Barley
Citrus
Corn, field
Cottonseed
Cottonseed, processed commodities (meal, hulls,
and refined oil)
Fig
Flax
Grape
Mint
Oats
Peanut
44009601
Data Required
00113203,43451701
00058827, 00058828, 43577401, 43666801
43585301
Required4
44061201
43991401
43548401
44124801
Data Required
00035130, 00080769, 00089808
146
-------
New
Guideline
Number
860.1480
860.1460
860.1850
860.1900
870.1000
870.1100
870.1200
870.2400
870.2500
Old
Guideline
Number
153-3
171-41
153-3
153-3
81-1
81-2
81-3
81-4
81-5
Study Description
Pineapple
Potato
Rice
Rye
Sorghum
Sunflower
Tomato
Wheat
Citation/ Data Required
44613801
43524101
00058824,43562301
Data Required
00058828
00096676
43499901
00034951, 00058826, 00058828, 00089808,
43510501,43661401
Meat, Milk, Poultry, Eggs
Fat, Meat, and Meat Byproducts of cattle, goats,
hogs, horses, and sheep
Milk
Eggs and the Fat, Meat, and Meat Byproducts of
Poultry
Water, Fish and Irrigated Crops
Food Handling
Confined Rotational Crops
Field Rotational Crops
Oral - Rat
Acute Dermal -Rabbit
Acute Inhalation Toxicity
Primary Eye Irritation - Rabbit
Primary Dermal Irritation
00082336, 00113120, 00113191, 00120105
0005309, 00034457, 00034461, 00088051,
00089255, 00089562, 00113101, 00113175,
00120105, 05006630
00108941, 00113234, 00113236
Data Required
00163283
00058825
To be determined
Required5
00159876
00159877
00159878
00159880
00159879
147
-------
New
Guideline
Number
870.2600
870.3200
870.3465
870.3700a
870.3700b
870.4100b
870.4200a
870.3800
870.4300
870.5100
870.5300
870.5385
870.5550
870.6100
870.6200(a)
870.6200(b)
870.6300
870.6300(x)
870.7485
870.7800
Old
Guideline
Number
81.6
82-2
82-4
83-3a
83-3b
83-lb
83-2a
83-4
83-5
84-2a
84-2
84-2
84-2
Study Description
Dermal Sensitization
21 -Day Dermal -Rabbit
90-Day Inhalation - Rat
(range finding study)
Developmental Toxicity - Rat
Developmental Toxicity - Rabbit
Chronic Toxicity (nonrodent)
Oncogenicity (rat)
2 - generation Reproduction, Rat
Chronic/Oncogenicity (rat)
Mutagenicity — Gene Mutation - bacterial
Mutagenicity - Lymphoma Forward Gene
Mutation Assay
Mutagenicity - Bone Marrow Chromosome
Aberration Test
DNA Synthesis
Acute Oral Delayed Neurotoxicity
Acute Neurotoxicity - Rat
Subchronic Neurotoxicity - Rat
Developmental Neurotoxicity - Rat
Comparative ChE Study - Rat
Metabolism - Rat
Immunotoxicity
Citation/ Data Required
00159881
41054201,46790501
43266601
(44554301)
41160901
00152569
40188501
43942901,43975201
41583401
43407201
40939302
45554501
41451201
41389301
40939301
43146701
43269501
45646401
45566201
41367701
Required
148
-------
1: Required regarding use of ground or aerial equipment, unless adequate field trial data reflecting aerial application of malathion in <2 gallons of
water per acre (<19 gallons of water per acre for tree or orchard crops) are available, malathion product labels must specify that aerial application
ar to be made in a minimum of 2 gallons of water per acre (10 gallons per acre in the case of tree or orchard crops).
2: This data requirement(s) imposed in the Malathion Reregistration Standard remain outstanding. In lieu of the required residue data, the
registrant(s) may modify malathion use to allow broadcast use only over intermittently flooded areas, and that applications may not be made
around bodies of water where fish or shellfish are grown and/or harvested commercially.
3: Residue in/on the following RAC's following preharvest uses have not been fulfilled: barley hay; celery; corn (sweet) stover; cottonseed;
cotton gin byproducts; date (currently under review); oat hay; quince; sorghum forage and stover; and, wheat hay.
4: The reregistration data requirements for magnitude of the residue in the processed commodities of the following crops are required: flax; and
wheat (reflecting postharvest treatment). Additionally, processing data for peanut, plum, rice (reflecting postharves treatment) safflower;
sugarbeet; soybean; and, sunflower are required should any registrant elect to support uses of malathion on these crops.
5: Rotational crop restrictions are needed on malathion end-use product labels. The appropriate PBIs will be determined pending submission of
the required field rotational crop studies.
149
-------
Appendix C
Technical Support Documents for the Malathion RED
Health Effect Documents
Malathion: Revised Acute, Probabilistic and Chronic Dietary (Food + Drinking Water) Exposure
and Risk Assessments for the Malathion Reregi strati on Eligibility Decision. PC Code: 057701.
DP Barcode: D330636. Sheila Piper, July 13, 2006.
Malathion: Residential Exposure and Risk Assessment for the Reregi strati on Eligibility Decision
(RED) Document. (DP Barcode: D330678; Chemical Number: 057701; EPA MRID No.:
43945001). Jack Arthur, July 6, 2006.
Malathion: Residential Exposure and Risk Assessment for the Reregi strati on Eligibility Decision
(RED) Document. PC Code: 057701. DP Barcode: D321547. Jack Arthur. September 12, 2005.
Malathion: Occupational Exposure and Risk Assessment for the Reregi strati on Eligibility
Decision (RED) Document. (DP Barcode: D330675; Chemical Number: 057701; EPA MRID
Nos.: 45005910, 45491901, 45138202, 45491902, 45138201 and 45469501). Jack Arthur, July 6,
2006.
Malathion: Occupational Exposure and Risk Assessment for the Reregi strati on Eligibility
Decision (RED) Document. PC Code: 057701. DP Barcode: D315898. Jach Arthur. June 2,
2005.
Second Update Review of Malathion Incident Reports. PC Code: 057701. DP Barcode
D315907. Jerome Blondell. May, 2005.
Product Chemistry Chapter for the Malathion Reregi strati on Eligibility Decision (RED)
Document. William O. Smith. DP Barcode D256522. June 2, 1999.
Residue Chemistry Chapter for the Malathion Reregi strati on Eligibility Decision (RED)
Document. PC Code: 057701. DP Barcode: D239453. William O. Smith. April 14, 1999.
Benchmark Dose Analysis of Brain and Rbc Data from the Malathion Comparative
Cholinesterase Study in Juvenile and Adult Rats. PC Code: 057701. DP Barcode: D315405.
AnnaLowit. April 11, 2005.
Malathion and Malaoxon: Comparative Toxicity and Estimation of Toxicity Adjustment Factor.
PC Codes: 057701, 657701. DP Barcodes: D293912, D295144, D310501, D310800. Anna
Lowit. April 11,2005.
Environmental Fate and Ecological Effects Documents
Revised EFED RED Chapter for Malthion. PC Code: 057701. DP Barcodes: D238903, and
D238906. Brian Montague, Norman Birchfield, Richard Mahler. October 18, 2000.
150
-------
Estimates of Malathion Concentrations in Drinking Water as a Result of Terrestrial Uses and Rice
Use. PC Code: 057701. DP Barcode: D285199. Norman Birchfield. September 16, 2002.
Transmittal of Estimated Daily Drinking Water Concentrations of Malaoxon Resulting from
Malathion use on Multiple Crops at Typical and Maximum Intensity. PC Code: 057701. DP
Barcode: D292663. Norman Birchfield. June 30, 2004.
Estimated Chronic Drinking Water Exposure Values for Malaoxon. PC Code: 057701. DP
Barcode: D315267. Norman Birchfield. March 24, 2005.
Drinking Water Exposure Modeling Evaluating the Effect of Varying Crop Scenarios,
Application Rate, Application Interval, Spray Drift Levels, Soil Half Life. PC Code: 057701; DP
Barcode: D327331. Norman Birchfield, June 15, 2006.
Spray Drift Deposition and Dissipation Distances from Aerial Application opf Aqueous and Oil
Malathion Formulations. PC Code: 057701. DP Barcode: D328380. Norman Birchfield. June 15,
2006.
Biological and Economical Analysis Documents
Summary Tables of Malathion Grower Impact on Selected Crops. Donald Atwood. Jan 18, 2006.
Registered Crops with Little to No Use of Malathion. Donald Atwood, Jin Kim, Tim Kiely. Dec.
23, 2005.
151
-------
Appendix D
MRID Citation Reference
1999 Atkins, L., Jr.; Anderson, L.D. (1967) Toxicity of Pesticides and Other Agricultural
Chemicals to Honey Bees: Laboratory Studies. (Unpublished study received Jan 30, 1969
under 9G0802; prepared by Univ. of California—Riverside, Dept. of Entomology, submitted
by Hercules, Inc., Agricultural Chemicals, Wilmington, Del.; CDL:093111-D) Author:
Atkins, L., Jr. Anderson, L.D.
5309 Eschle, J.L.; Miller, JA. (1967) Ultra-Low-Volume Application of Insecticides to Cattle for
Control of the Horn Fly: Report No. 20820. (Unpublished study received Feb 6, 1969 under
11556- 16; prepared by U.S. Agricultural Research Service, Entomology Research Div.,
Livestock Insects Investigations for Chemagro Corp., submitted by Bayvet, Shawnee
Mission, Kans.; CDL: 007194-G)
22923 Hill,E.F., RG. Heath, J.W. Spann and J.D. Williams. 1975. Lethal dietary toxicities of
environmental pollutants to birds. USDI, Fish and Wildlife Service, Patuxent Wildlife
Research Center. USFWS Special Scientific Report -Wildlife, No. 191. (unpublished
report).
30482 Snetsinger, R.; Chung, S.L.; Kielbasa, R.; et al. (1979) Ethoprop: Sciarid Fly Control in
Mushrooms. (Unpublished study including PR No. 908 and published data, received Mar 27,
1980 under OE2341; prepared in cooperation with Pennsylvania State Univ., Dept. of
Entomology, submitted by Interregional Research Project No. 4, New Brunswick, N.J.;
CDL:099351-C)
33810 American Cyanamid Company (1965) Malathion Residues on Tomatoes. (Unpublished study
received Aug 26, 1968 under 241-47; CDL: 001672-B)
34342 McGregor, H.E. (1972) Progress Report: Malathion for Insect Control in Flour Mills.
Includes undated method entitled: Determination of Malathion in various mill streams of
wheat. (Unpublished study received Feb 15, 1973 under 241-47; prepared by U.S. Agri-
cultural Research Service, Mid-West Grain Insects Investiga- tions, Grain Marketing
Research Center in cooperation with Gen- eral Mills, submitted by American Cyanamid Co.,
Princeton, N.J.; CDL:001678-A)
34344 Amen, C.R.; Telford, H.S.; Legault, R.R.; et al. (1959) Monthly Re-port: Malathion-
Residues in Asparagus. (Unpublished study re- ceived Nov 3, 1959 under 241-30; prepared
in cooperation with State College of Washington, Depts. of Entomology and Agricul- tural
Chemistry, submitted by American Cyanamid Co., Princeton, N.J.; CDL:001635-A)
34457 Turner, C. (1959) Horn Fly Tests. (Unpublished study received Mar 10, 1959 under 241-33;
prepared by Virginia Polytechnic Insti- tute, submitted by American Cyanamid Co.,
Princeton, N.J.; CDL: 001653-A)
34458 Dickason, E.A.; Amen, C.R; Tuft, T.O. (1960) ?Control of Insects on Vetch). (Unpublished
study received Oct 10, 1960 under 241-33; prepared in cooperation with Oregon State
College and Hazle- ton Laboratories, Inc., submitted by American Cyanamid Co., Princeton,
N.J.; CDL:001654-A)
152
-------
34461 Wells, A.L.; Stelmach, Z.; Guyer, G.E.; et al. (19??) A Study of Malathion for Controlling
Flies in Dairy Barns and on Dairy Cat- tie. Michigan Quarterly Bulletin 40(4):786-795.
(Also~In~un- published submission received Apr 2, 1962 under 241-33; submit- ted by
American Cyanamid Co., Princeton, N.J.; CDL:001656-B)
34951 Phillips, G.L.; Moore, S., Ill (1970) ?Efficacy Data for Malathion on Wheat]. (Unpublished
study including letter dated Sep 30, 1970 from J.R. Dogger to E. Brad Fagon, received Feb
10, 1971 under 241-47; prepared by U.S. Agricultural Marketing Service, Marketing
Research Div., Stored-Grain Insects Laboratory in co- operation with Univ. of Illinois,
Cooperative Extension Service, Illinois Natural History Survey, submitted by American
Cyanamid Co., Princeton, N.J.; CDL:001674-A)
35013 Orloski, E.J.; Whalen, R.T.; Owens, W.L., Jr. (1968) Malathion Res- idues in Grain
Sorghum: Report No. C-162. (Unpublished study received Aug 16, 1968 under 241-110;
submitted by American Cyanamid Co., Princeton, N.J.; CDL:001998-A)
35014 American Cyanamid Company (19??) ?Extraction of Malathion from Grain Sorghum;
Determination of Malathion in Carbon tetrachlo- ride Extracts). (Unpublished study received
Aug 16, 1968 under 241-110; CDL:001998-B)
35015 Orloski, E.J.; Snyder, E.H.; Roberts, W.W. (1964) Malathion Resi- dues in Blueberries:
Report No. C-66. (Unpublished study re- ceived Apr 26,1965 under 241-110; submitted by
American Cyana- mid Co., Princeton, N.J.; CDL:001994-A)
35130 American Cyanamid Company (1960) Malathion Recovery Studies on Pea-nut Products:
Project BS 1-32. (Unpublished study received Aug 30, 1960 under241-47; prepared in
cooperation with U.S. Dept. of Agriculture, Stored Product Insects Branch, Savannah
Station; CDL:001668-B)
35314 Kiigemagi, U.; Terriere, L.C. (1968) Malathion Residues on Cherries Treated with an Ultra
Low Volume Formulation. (Unpublished study including letter dated Dec 1, 1969 from U.
Kiigemagi to C. R. Amen, received Feb 6, 1970 under 241-108; prepared by Oregon State
Univ., Dept. of Agricultural Chemistry,submitted by American Cyanamid Co., Princeton,
N.J.; CDL:002001-B)
35318 Orloski, E.J.; Whalen, R.T.; Cowan, C.B.; et al. (1966) Malathion Residues in Cottonseed:
Report No. C-103. Includes method dated Jan 18, 1966. (Unpublished study including report
no. C-104, received Jan 26, 1966 under 241-110; submitted by American Cyan- amid Co.,
Princeton, N.J.; CDL:001995-B)
35330 Orloski, E.J.; Devine, J.M.; Pass, B.C.; et al. (1969) Malathion and
Methyl parathion Residues in Alfalfa: Report No. C-217. Includes undated method entitled:
Gas chromatographic deter- mination of Malathion and Methyl parathion residues in alfalfa
(green foliage and dry hay). (Unpublished study received Feb 19, 1970 under 241-219;
prepared in cooperation with Syracuse Univ. Research Corp., submitted by American
Cyanamid Co., Princeton, N.J.; CDL:002059-C)
35870 Zabik, M. (1970) ULV Malathion Residues on Cherries: Sample Analyt- ical Procedure.
Undated method. (Unpublished study received Feb 18, 1971 under 241-224; prepared by
Michigan State Univ., Pesticide Analytical Laboratory, submitted by American Cyanamid
Co., Princeton, N.J.; CDL:002062-C)
153
-------
35886 Orloski, E.J.; Bohn, W.R.; Whalen, R.T.; et al. (1967) Malathion Residues in Green Alfalfa:
Report No. C-139. Includes method entitled: Determination of Malathion in Benzene
extracts. (Un- published study received Apr 8, 1968 under 241-110; submitted by American
Cyanamid Co., Princeton, N.J.;CDL:001996-B)
35890 Borough, H.W.; Randolph, N.M. (1967) Comparative Residual Nature of certain Insecticides
Applied as Low Volume Concentrate and Water Emulsion Sprays. Bulletin of
Environmental Contaimination & Toxicology 2(6):340-342.(Also~In~unpublished
submission re- ceived Apr 1, 1969 under 241-219; submitted by American Cyanamid Co.,
Princeton, N.J.; CDL:002059-F)
35890 Borough, H.W.; Randolph, N.M. (1967) Comparative Residual Nature of certain Insecticides
Applied as Low Volume Concentrate and Water Emulsion Sprays. Bulletin of
Environmental Contaimination & Toxicology 2(6):340-342. (Also~In~unpublished
submission re- ceived Apr 1, 1969 under 241-219; submitted by American Cyanamid Co.,
Princeton, N.J.; CDL:002059-F)
48370 U.S. Department of Agriculture (1973) ?Efficacy Studies~Raisins|. (Compilation;
unpublished study; CDL:221775-H)
57674 American Cyanamid Company (1952) Malathon. N.P. (Technical bulletin no. 2;
also~In~unpublished submission received Mar 15, 1952 under unknown admin, no.;
CDL:001580-A)
58823 Manuel, A.J. (1976) Malathion: Determination of Residues of Mala- thion, (CL 6,601), S-
?l,2-Bis(ethoxycarbonyl)ethyl|-O,O-dimeth- yldithiophosphate, and Malaoxon (CL 23,269)
in Beef and Pork Muscle, Bread, Cake, Corn Flakes, Milk, Coca-Cola, and Cranberry Sauce
by Gas-Liquid Chromatography: Report No. C-919. Includes method M-647 dated Mar 12,
1976. (Unpublished study received Aug 16, 1976 under 241-EX-83; submitted by American
Cyanamid Co., Princeton, N.J.; CDL:230458-D)
58824 Alvarez, C.G.; McGaughey, W.H. (1975) Malathion on Milling Frac- tions of Three
Varieties of Rough Rice: Duration of Protection and Residue Degradation, USDA, ARS,
Market Quality Research Division, Beaumont, Texas~1969:ReportNo. 75-123. (Unpub-
lished study including published data, received Aug 16, 1976 under 241-EX-83; prepared in
cooperation with U.S. Agricultural Research Service, Market Quality Research Div., Stored-
Product Insects Research Branch, submitted by American Cyanamid Co., Princeton, N.J.;
CDL:230458-E)
58825 Alvarez, C.G.; Bliznick, A.; McGregor, H.; et al. (1975) Malathion in Flour Mills, USDA,
ARS, Mid-west Grain Insects Investiga- tions, Manhattan, Kansas—1971: Report No. 75-124.
Includes un- dated method entitled: Determination of Malathion in various mill streams of
wheat. (Unpublished study received Aug 16, 1976 under 241-EX-83; prepared in
cooperation with U.S.Agricultural Research Service, Market Quality Research Div., Stored-
Product Insects Research Branch, Mid-West Grain Insects Investigations Laboratory,
submitted by American Cyanamid Co., Princeton, N.J.; CDL:230458-F)
154
-------
58825 Alvarez, C.G.; Bliznick, A.; McGregor, H.; et al. (1975) Malathion in Flour Mills, USDA,
ARS, Mid-west Grain Insects Investiga- tions, Manhattan,Kansas--1971: Report No. 75-124.
Includes un- dated method entitled: Determination of Malathion in various mill streams of
wheat. (Unpublished study received Aug 16, 1976 under 241-EX-83; prepared in
cooperation with U.S. Agricultural Research Service, Market Quality Research Div., Stored-
Product Insects Research Branch, Mid-West Grain Insects Investigations Laboratory,
submitted by American Cyanamid Co., Princeton, N.J.; CDL:230458-F)
58826 Alvarez, C.G.; Edmonds, W.O. (1975) Malathion Residues on Milled Fractions of Malathion
Treated Wheat, Minneapolis, Minnesota— 1958-59: Report No. 75-40. Includes method M
18 dated Feb 1955. (Unpublished study received Aug 16, 1976 under 241-EX-83; pre- pared
in cooperation with U.S. Dept. of Agriculture, Stored Products Insects Section and Pillsbury
Mills, Inc., submitted by American Cyanamid Co., Princeton, N.J.; CDL:230458-G)
58827 Alvarez, C.G.; McGregor, H.E.; Henderson, L.S.; et al. (1975) Resi- due Studies on Corn and
Milled Corn Fractions, USDA, ARS, Mid- west Grain Insects Investigations, Manhattan,
Kansas-1972: Report No. 75-125. (Unpublished study received Aug 16, 1976 under 241-
EX-83; prepared in cooperation with U.S. Agricultural Research Service, Mid-west Grain
Insects Investigations Laboratory and Stored Products Laboratory, submitted by American
Cy- anamid Co., Princeton, N.J.; CDL:230458-H)
58828 Alvarez, C.G.; Schesser, J.H.; Wilson, J.L.; et al. (1975) Persistence of CythionA(R)I
Residues on Stored Grains: Corn, Wheat and Grain Sorghum: Report No. 75-122.
(Compilation by submit- ter; unpublished study including published data, received Aug 16,
1975 under 241-EX-83; submitted by American Cyanamid Co., Princeton, N.J.;
CDL:230458-I)
80769 ICI Americas, Incorporated (1977) ?Efficacy of Pirimiphos-methyl on Peanuts).
(Compilation; unpublished study, including published data, received Dec 1, 1978 under
10182-EX-15; CDL: 097674-H)
82336 Claborn, H.V. (1956) Insecticide Residues in Meat and Milk: ARS- 33-25. (U.S. Agricultural
Research Service, Entomology Research Branch; unpublished study; CDL:097556-J)Author:
Claborn, H.V.
85524 California Spray-Chemical Company (1955) Spray Residue Remaining from the Use of
Captan as an Agricultural Fungicide. (Compilation; unpublished study received May 1, 1955
under PP0015; CDL: 090983-N)
88051 Claborn, H.V. (1955) Insecticide Residues in Meat and Milk. (U.S. Agricultural Research
Service, Entomology Research Branch; un-published study; CDL:090081-X)Author:
Claborn, H.V.
89052 American Cyanamid Company (1956) Method of Residue Analysis. (Un- published study
received on unknown date under PP0064; CDL: 090062-A)
89237 Norris, M.V.; Vail, W.A.; Averell, A.R (1954) Colorimetric Method for the Determination
of Malathion Residues on Fruits, Vegetables, etc. Method dated Jan 1954, including method
dated Aug 1954 entitled: Freeze-drying of milk. (Unpublished study received Jun 1, 1955
under PPOO19; CDL:090018-AM)
155
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89239 American Cyanamid Company (1954) ?Residue Study of Malathion on Various Fruits).
(Compilation; unpublished study received on unknown date under PP0019; CDL:090018-
AO)
89242 American Cyanamid Company (1954) ?Residue Study of Malathion on Blueberries and
Various Other Berries|. (Compilation; unpublished study received Jun 1, 1955 under
PP0019; CDL:090018-AR)
89245 American Cyanamid Company (1954) ?Residue Study of Malathion on Beans].
(Compilation; unpublished study received Jun 1, 1955 under PP0019; CDL:090018-
AV)Citation: American Cyanamid Company (1952) Malathion Residues: Beets. (Un-
published study received Jun 1, 1955 under PP0019; CDL: 090018-AW)
89247 American Cyanamid Company (1954) Malathion Residues: Celery. (Un- published study
received Jun 1, 1955 under PP0019; CDL: 090018-AX)
89248 American Cyanamid Company (1954) ?Residue Study of Malathion on Rutabagas, Onions
and Potatoes). (Compilation; unpublished study received Jun 1, 1955 under PP0019;
CDL: 090018-AY)
89249 American Cyanamid Company (1955) ?Residue Study of Malathion on Cantaloupes,
Cucumbers and Squash). (Compilation; unpublished study received Jun 1, 1955 under
PP0019; CDL:090018-AZ)
89250 American Cyanamid Company (1954) ?Residue Study of Malathion on Eggplants, Peppers
and Tomatoes). (Compilation; unpublished study received Jun 1, 1955 under PP0019;
CDL: 090018-BA)
89251 American Cyanamid Company (1952) Malathion Residues: Peas. (Unpublished study
received Jun 1, 1955 under PP0019; CDL:090018-BB)
89252 American Cyanamid Company (1955) ?Residue Study of Malathion on Alfalfa and Red
Clover). (Compilation; unpublished study re- ceived Jun 1, 1955 under PP0019;
CDL:090018-BC)
89253 American Cyanamid Company (1955) ?Residue Study of Malathion on Pasture Grass,
Barley, Oats and Wheat). (Compilation; unpublished study received Jun 1, 1955 under
PP0019; CDL:090018-BD)
89254 American Cyanamid Company (1955) ?Residue Study of Malathion on Pineapples and
Various Other Fruits). (Compilation; unpublished study received Jun 1, 1955 under PP0019;
CDL:090018-BF)
89255 American Cyanamid Company (1955) Malathion Residues: Milk. (Unpublished study
received Jun 1, 1955 under PP0019; CDL:090018-BG)
89256 Gjullin; C.M.; Scudder, H.I.; Erwin, W.R (1955) Determination of Malathion and Its
Influence on Flavor of Milk from Cows Fed Malathion-sprayed Alfalfa. (Unpublished study
received Jun 1, 1955 under PP0019; prepared by U.S. Dept. of Agriculture, Entomology
Research Branch and others, submitted by American Cyanamid Co., New York, N.Y.;
CDL: 090018-BH)
156
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89258 American Cyanamid Company (1954) ?Residue Study of Malathion on Apples and Pears|.
(Compilation; unpublished study received Jun 1, 1955 under PP0019; CDL:090018-BJ)
89259 American Cyanamid Company (1955) Removal of Malathion Residues on Broccoli in a
Commercial Freezing Plant by Washing. (Unpublished study received Jun 1, 1955 under
PP0019; CDL:090018-BK)
89260 American Cyanamid Company (1956) ?Residue Study of Malathion on Broccoli and Various
Other Vegetables). (Compilation; unpublished study received Jun 1, 1955 under PP0019;
CDL:090018-BL)
89521 American Cyanamid Company (1963) ?Malathion Residues in Forage Crops, Alfalfa, Meat
and Dairy Products). (Compilation; unpub- lished study, including published data and report
no.s C-33 and C-34, received Jun 1, 1964 under PP0407; CDL:090023-F)
89562 American Cyanamid Company (1957) ?Residue Study of Malathion in Milk|. (Compilation;
unpublished study received Oct 15, 1957 under PP0150; CDL:090002-C)
89593 American Cyanamid Company (1958) ?Analyses for Residues of Malathion in Figs|.
(Compilation; unpublished study received Mar 28, 1958 under PP0187; CDL:090215-A)
89808 American Cyanamid Company (1957) ?Residues of Insecticides~Grain|. (Compilation;
unpublished study received Apr 10, 1957 under PP0136; CDL:090164-B)
96676 Interregional Research Project Number 4 (1982) Malathion and Ma- laoxon Residues Found
in Sunflower Seeds or Hulls Treated with Malathion.(Compilation; unpublished study
received Mar 17, 1982 under 2E2658; CDL:070717-A)
98775 Paulin, H.J. (1971) Final Report: Determination of Pesticide Residues in Hog Tissue.
(Unpublished study received on unknown date under 3E1367; prepared by TRW, Inc.,
submitted by American Seed Trade Association, Inc., Kalamazoo, Mich.; CDL:093649-K)
100020 American Cyanamid Co. (1966) Malathion Residues on Various Vegetable, Berry and
Tobacco Crops). (Compilation; unpublished study received Jul 19, 1966 under unknown
admin, no.; CDL: 124480-A)
101150 Painter, R.; Kilgore, W.; Ough, C. (19??) Distribution of pesticides in fermentation products
obtained from artificially fortified grape musts. ?Source unknown) p.342-346. (Also In
unpublished submission received Oct 7, 1964 under 100-460; submitted by Ciba-Geigy
Corp., Greensboro, NC; CDL;101158-D)
102291 Walker, R.; Yeomans, A.; Fahey, J.; et al. (1965) Comparative Studies of Ultra Low-volume
Sprays and Conventional Emulsion Sprays of Malathion and Methyl Parathion Applied to
Cotton for Insect Control. (U.S. Agricultural Research Service, Entomology Research Div.,
Analytical Investigations, Aerosol Investigations, Biological Investigations and Plant Pest
Control Div.; unpublished study; CDL:005066-B)
102376 Peterson, R.; Pasarela, N. (1969) Malathion and Methyl Parathion Residues in Ground
Undelinted Cottonseeds: Report No. C-181. (Unpublished study received Feb 19, 1969 under
241-EX-49; submitted by American Cyanamid Co., Princeton, NJ; CDL: 123158-G)
157
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103342 Kim, D.; Gagne, J. (1982) Pay-Off Flucythrinate (CL 222,705/2.5EC),Cythion Malathion
(CL 6,601/ULV): Residues of CL 222,705 and CL 6,601 in Cottonseeds (AER; LA, 1981)
(C-0181, C-0261 and C-1593): Report No. C-1993. (Unpublished study received Jun 7, 1982
under 241-110; submitted by American Cyanamid Co., Prince- ton, NJ; CDL:247650-A)
103343 Kim, D.; Gagne, J. (1982) Pay-Off Flucythrinate (CL 222,705/2.5EC), Cythion Malathion
(CL 6,601/ULV): Residues of CL 222,705 and CL 6,601 in Cottonseeds (AER; GA, 1981)
(C-0181, C-0261 and C-1593): Report No. C-2027. (Unpublished study received Jun 7, 1982
under 241-110; submitted by American Cyanamid Co., Prince- ton, NJ; CDL:247650-B)
104631 IR-4 Project (1975) (Efficacy of Malathion on Almonds and Other Crops). (Compilation;
unpublished study received Aug 21, 1978 under 8E2114; CDL:097309-C)
105387 Storherr, R.; Roberts, J. (1958) Insecticide Residues on Georgia Crops. (Unpublished study
received Nov 1, 1970 under unknown admin, no.; prepared by Univ. of Georgia, Experiment
Station, submitted by Hercules, Inc., Agricultural Chemicals, Wilmington, DE;
CDL:005105-E)
108941 American Cyanamid Co. (1968) Results of Tests on the Amount of Residues Remaining,
Including a Description of the Analytical Methods Used: Malathion. (Compilation;
unpublished study received on unknown date under 8F0634; CDL:090122-B)
108942 March, R; Fukuto, T.; Metcalf, R.; et al. (1956) Fate of P32-labeled malathion in the laying
hen, white mouse, and American cockroach. Journal of Economic Entomology 49(2): 185-
195. (Also In unpublished submission received Aug 8, 1967 under 8F0634; submitted by
American Cyanamid Co., Princeton, NJ; CDL:090122-E)
108949 American Cyanamid Co. (1957) ?Analyses for Residues of Malathion in Black Raspberry
Fruit and Other Products). (Compilation; unpublished study received on unknown date under
PP0089;CDL: 090131-A)
113095 American Cyanamid Co. (1973) ?Residues of Malathion in Raisins). (Compilation;
unpublished study received Feb 15, 1974 under 241-208; CDL:026767-A)
113097 American Cyanamid Co. (1967) ?Residues of Malathion in Cottonseed). (Compilation;
unpublished study received Aug 4, 1967 under 241-186; CDL:026906-B)
113099 American Cyanamid Co. (1973) Residue Data: Malathion). (Compilation; unpublished study
received May 20, 1974 under 241-110; CDL:026910-B)
113099 American Cyanamid Co. (1973) Residue Data: Malathion). (Compilation; unpublished study
received May 20, 1974 under 241-110; CDL:026910-B)
113100 Orloski, E.; Whalen, R. (1964) Malathion Residues in MacadamiaNuts: Report No. C-62.
(Unpublished study received Jul 15, 1964 under 241-30; submitted by American Cyanamid
Co., Prince- ton, NJ; CDL:026952-A)
113101 Orloski, E.; Whalen, R; Adkins, T.; et al. (1964) Malathion Residues in Milk: Report No. C-
51. (Unpublished study received Apr 3, 1964 under 241-30; submitted by American
Cyanamid Co., Princeton, NJ; CDL:026954-A)
158
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113116 American Cyanamid Co. (1954) The Results of Tests on the Amount of Residue Remaining,
Including a Description of the Analytical Method Used:(Malathion). (Compilation;
unpublished study received Jul 1, 1955 under PP0019; CDL:090774-L)
113118 Legault, R.; Cone, W. (1968) The Results of Tests on the Amount of Malathion Residue
Remaining on Hops, Including a Description of the Analytical Method Used. (Unpublished
study received May 4, 1970 under OE0891; prepared by Washington State Univ., Dept. of
Agricultural Chemistry, submitted by Interregional Research Project No. 4, New Brunswick,
NJ; CDL:091534-A)
113120 American Cyanamid Co. (1960) The Results of Tests on the Amount of Residues Remaining;
A Description of the Analytical Method Used: Malathion|. (Compilation, unpublished study
received Apr 22, 1960 under PP0252;CDL:091560-B)
113121 American Cyanamid Co. (1969) Results of Tests on the Amount of Residues Remaining,
Including a Description of the Analytical Methods Used: Malathion. (Compilation;
unpublished study received Jul 22, 1970 under OF0942; CDL:091610-A)
113134 Dogger, J. (1969) Letter sent to W. Stokes dated Aug 1, 1969: Petition for temporary
tolerance for malathion in unprocessed shelled almonds.(U.S. Agricultural Research Service,
Market Quality Research Div., Stored-Product Insects Research Branch; unpublished study;
CDL:093161-A)
113135 Interregional Research Project No. 4 (19??) Procedure for Deter- mining Malathion in Hop
Cones. (Unpublished study received Sep 29, 1969 under OE0891; CDL:093188-A)
113137 Interregional Research Project No. 4 (1978) The Results of Tests on the Amount of
Malathion Residues Remaining in or on Flax (Seed, Straw, Meal) Including a Description of
the Analytical Method Used. (Compilation; unpublished study received Aug 16, 1979 under
9E2248; CDL:098913-A)
113138 American Cyanamid Co. (1955) Colorimetric Method forthe Determination of Malathion in
Milled Wheat Products. (Unpublished study received Apr 10, 1957 under PP0136;
CDL:092417-A)
113139 American Cyanamid Co. (1958) Study: Malathion Efficacy against Keds, Lice, and Ticks on
Sheep & Goats]. (Compilation; unpublished study received on unknown date under PP0187;
CDL: 092463-A)
113140 American Cyanamid Co. (1960) Study: Malathion Efficacy on Pea- nuts|. (Compilation;
unpublished study received Oct 6, 1960 under PP0275; CDL:092554-A)
113141 American Cyanamid Co. (1960) Malathion Recovery Studies on Peanut Products: Exp. No.
9. (Unpublished study received Oct 6, 1960 under PP0275; CDL:092554-B)
113142 Spitler, G. (1966) Evaluation of Malathion as an Insect Protectant for Inshell Almonds Stored
under Commercial Conditions in Chico, Calif. (U.S. Agricultural Research Service, Market
Quality Re- search Div.; unpublished study; CDL:092829-A)
113143 Interregional Research Project No. 4 (1976) (Determination of Malathion and Malaoxon
Residues in Various Crops). (Compilation; unpublished study received Oct 27, 1976 under
7E1881;CDL:097770-A)
159
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113144 Interregional Research Project No. 4 (1976) (Efficacy of Malathion Used to Control Wild
Rice Worm, Apamia apamiformis). (Compilation; unpublished study received Oct 27, 1976
under 7E1881; CDL: 097770-B)
113147 Higham, J.; Dunn, J.; Blalock, J.; et al. (1974) Cythion ULV: Cythion ..., DBF ..., and Folex
... Residues in Cottonseed Treated with Cythion-DEF and Cythion-Folex Tank Mixtures
(South Carolina, Tennessee, and Texas): C-467. (Unpublished study received Jul 18, 1974
under 241-208; prepared in cooperation with State Univ.—Oswego, Lake Ontario
Environmental Laboratory and Mobil Chemical Co., submitted by American Cyanamid Co.,
Princeton, NJ; CDL: 100867-A)
113148 McNerney, J.; Levinskas, G.; Morici, I.; et al. (1966) Report on Proban Cythioate: Joint
Toxic Action with Other Organic Phosphates and Phenothiazine Tranquilizers: Report No.
66-83. (Un- published study received Sep 23, 1966 under 241-190; submitted by American
Cyanamid Co., Princeton, NJ; CDL:101045-A)
113149 American Cyanamid Co. (1965) Determination of Residues of Malathion in Lettuce|.
(Compilation; unpublished study received Dec 8, 1965 under 241-30; CDL: 101275-A)
113150 American Cyanamid Co. (1965) Malathion Residues on Tomatoes. (Un- published study
received Aug 26, 1968 under 241-47; CDL: 101276-A)
113165 Marucci, P. (1960) Letter sent to H. Scott dated Oct 10, 1960 Request for 0-day label for use
of malathion on blueberries). (Unpublished study received Oct 25, 1960 under unknown
admin, no.; prepared by Rutgers Univ., Agricultural Experiment Station, Dept. of
Horticulture, Cranberry and Blueberry Research Laboratory, submitted by American
Cyanamid Co., Princeton, NJ; CDL: 119963-A)
113166 Kiigemagi, U.; Crowell, H. (19??) Determination of Malathion on Green Beans.
(Unpublished study received Apr 4, 1957 under un- known admin, no.; prepared by Oregon
State College, Ag Chem. Dept., and Entomology Dept., submitted by American Cyanamid
Co., Princeton, NJ; CDL: 119976-A)
113170 American Cyanamid Co. (1964) Determination of Malathion Residues in Blueberries).
(Compilation; unpublished study received Feb 27, 1964 under unknown admin, no.;
CDL:119980-A)
113171 American Cyanamid Co. (1965) Malation Residues in Lettuce]. (Compilation; unpublished
study received Dec 8, 1965 under unknown admin, no.; CDL: 119981-A)
113173 Mitchell, M.; Russell; Cleveland, R.; et al. (1971) Cygard 630: Malathion, Methyl Parathion
and Methyl Paraoxon Residues in Undelinted Cottonseed: Report No. C-261. (Unpublished
study re- ceived Mar 8, 1971 under unknown admin, no.; prepared in cooperation with
Syracuse Univ. Research Corp., submitted by American Cyanamid Co., Princeton, NJ;
CDL:120007-A)
113175 American Cyanamid Co. (1959) Malathion Residues on Beef and Diary Cattle.
(Compilation; unpublished study received Feb 20, 1959 under unknown admin, no.;
CDL: 120011-A) MRID: 113176
Citation: American Cyanamid Co. (1961) Malathion on Blueberries. (Unpublished study
received May 21, 1962 under unknown admin, no.; CDL: 120035-A)
160
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113182 Ohinata, K.; Seo, S.; Steiner, L. (1958) Data on Residues of Malathion on Several Different
Fruits and Vegetables. (U.S. Agricultural Research Service, Entomology Research Div.;
unpublished study; CDL:124454-A)
113186 Getz, M.; Skinner, F.; Beroza, M. (1966) Report of Residue Analysis: Malathion: Report No.
PCB-66-12. (U.S. Agricultural Re- search Service, Entomology Research Div., Pesticide
Chemicals Research Branch; unpublished study; CDL:124468-A)
113188 Maitlen, J.; McDonough, L.; Esvelt, S. (1966) Report of Residue Analysis: Malathion:
Report No. PCY-66-1. (U.S. Agricultural Research Service, Entomology Research Div.,
Pesticide Chemicals Research Branch; unpublished study; CDL:124471-A)
113191 Pasarela, N.; Brown, R.; Shaffer, C. (1962) Feeding of malathion to cattle: Residue analyses
of milk and tissue. Agricultural and Food Chemistry 10(1): 7-9. (Also In unpublished
submission received Feb 19, 1962 under unknown admin, no.; submitted by American
Cyanamid Co., Princeton, NJ; CDL:124485-A)
113193 American Cyanamid Co. (1963) Residues of Malathion in Blueberries. (Compilation;
unpublished study received Mar 18, 1964 under unknown admin, no.; CDL:124588-A)
113203 Anon. (1962) Methods for Determining the Amounts of Malathion in Bagged Citrus Pulp:
The Amounts There of and Removal. (Compilation; unpublished study received on unknown
date under unknown admin, no.; submitted by ?; CDL:221558-B)
113205 Anon. (1963) A Description of the Practicable Methods to Determine the Amount of
Malathion in or on Grapes (Raisins). (Compilation; unpublished study received Jan 10, 1964
under H1331; submitted by ?; CDL:221595-B)
113206 American Cyanamid Co. (1969) Study: Malathion Residue on Raisins). (Compilation;
unpublished study received Sep 15, 1971 under 2H2669; CDL:221731-A)
113212 American Cyanamid Co. (1951) Determination of Residues of Insecticide #4049 on Fruits,
Vegetables, etc. (Compilation; unpublished study received on unknown date under unknown
admin, no.; CDL:222410-C)
113214 American Cyanamid Co. (1952) Malathon Residues—Tomato. (Unpublished study received
Nov 19, 1952 under unknown admin, no.; CDL:222470-A)
113223 American Cyanamid Co. (1957) Residues of Malathion in Blueberries. (Compilation;
unpublished study received Oct 25, 1960 under unknown admin, no.; CDL:222490-A)
113229 American Cyanamid Co. (1963) Residues of Malathion in Blueberries and Other Crops).
(Compilation; unpublished study received May 24, 1963 under unknown admin, no.;
CDL:223807-A)
113230 American Cyanamid Co. (1962) Residues of Malathion in Safflower and Other Crops).
(Compilation; unpublished study received Jul 13, 1962 under 241-30; CDL:223808-A)
113234 Raun, E. (1956) Chicken louse and mite control with malathion formulations. ?Source
unknown) (Oct):628-629. (Also In unpubished submission received Jul 13, 1978 under
3770-277; submitted by Economy Products, Omaha, NE; CDL:234368-E)
161
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113236 Harding, W.; Quigley, G. (1956) Litter treatment with malathion to control the chicken body
louse. Journal of Economic Ento- mology 49(6): 806-807. (Also In unpublished submission
received Jul 13, 1978 under 3770-277; submitted by Economy Products, Omaha, NE;
CDL:234368-H)
115967 Office of Commissioner (1968) ?Study: Pesticide Residues in Selected Crops|.
(Compilation; unpublished study received Feb 21, 1969 under 7E0598; CDL:090766-A)
116023 Interregional Research Project No. 4 (1967) The Results of Tests on the Amount of DDT
Residue Remaining on Chestnuts and Walnuts Including a Description of the Analytical
Method Used. (Compilation; unpublished study received on unknown date under IE 1097;
CDL:090857-A)
120105 American Cyanamid Co. (1956) The Results of Tests on the Amount of Residues Remaining,
Including a Description of the Analytical Method Used: (Malathion). (Compilation;
unpublished study received Jul 22, 1966 under PP0089; CDL:090680-K)
122714 American Cyanamid Co. (1981) Residue Reports: Malathion. (Compilation; unpublished
study received Dec 17, 1982 under 241-110; CDL:071295-A)
138431 U.S. Dept. of Agriculture, European Corn Borer Research Laboratory (1956) Corn-
Malathion Residues. (Extract; unpublished study; CDL: 124484-A)
145201 American Cyanamid Co. (1984) Residue Studies [PAY-OFF Insecticide on Soybeans].
Unpublished compilation. 22 p.
152569 Siglin, J. (1985) A Teratology Study with AC 6,601 in Rabbits: FDRL Study No. 8171.
Unpublished study prepared by Food and Drug Research Laboratories. 204 p.
153985 Coffin, D. (1966) Oxidative metabolism and persistence of parathion and malathion on field-
sprayed lettuce. Journal ofthe A.O.A.C. 49(5):1018-1021.
153987 Dorough, H.; Randolph, N. (1967) Comparative residual nature of certain insecticides
applied as low volume concentrate and water emulsion sprays. Bulletin of Environmental
Contamination & Toxicology 2(6):340-348.
159270 Anon. (19??) Residues of Malathion from Sprays and Dusts on Vegetables and Berries.
Unpublished study.
159876 Kynoch, S. (1986) Acute Oral Toxicity to Rats of Malathion (Fyfanon) Technical:
851341D/CHV 33/AC. Unpublished study pre- pared by Huntingdon Research Centre Ltd.
159877 Kynoch, S. (1986) Acute Dermal Toxicity to Rats of Malathion (Fyfanon) Technical:
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43350401 Bookbinder, M. (1994) Magnitude of the Residue of Malathion and its Metabolite Malaoxon
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43350402 Bookbinder, M. (1994) Magnitude of the Residue of Malathion and its Metabolite Malaoxon
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43360001 Bookbinder, M. (1994) Magnitude of the Residue of Malathion and its Metabolite Malaoxon
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43360401 Bookbinder, M. (1994) Magnitude of the Residues of Malathion and its Metabolite
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43361101 Bookbinder, M. (1994) Magnitude of the Residue of Malathion and its Metabolite Malaoxon
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43362501 Bookbinder, M. (1994) Magnitude of the Residue of Malathion and its Metabolite Malaoxon
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43362601 Bookbinder, M. (1994) Magnitude of the Residue of Malathion and its Metabolite Malaoxon
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43367201 Bookbinder, M. (1994) Magnitude of the Residue of Malathion and Its Metabolite Malaoxon
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43368301 Bookbinder, M. (1994) Magnitude of the Residue of Malathion and Its Metabolite Malaoxon
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92/0059. Unpublished study prepared by EN-CAS Analytical Laboratories.
43370601 Bookbinder, M. (1994) Magnitude of the Residue of Malathion and its Metabolite Malaoxon
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92/0045. Unpublished study prepared by En-Cas Analytical Lab., American Agricultural
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43372601 Bookbinder, M. (1994) Magnitude of the Residue of Malathion and Its Metabolite Malaoxon
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AA920105: 92/0032. Unpublished study prepared by EN-CAS Analytical Laboratories and
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43372701 Bookbinder, M. (1994) Magnitude of the Residue of Malathion and Its Metabolite Malaoxon
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92/0037. Unpublished study prepared by EN-CAS Analytical Laboratories and American
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43372901 Bookbinder, M. (1994) Magnitude of the Residue of Malathion and Its Metabolite Malaoxon
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43376801 Bookbinder, M. (1994) Magnitude of the Residue of Malathion and its Metabolite Malaoxon
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43383301 Bookbinder, M. (1994) Magnitude of the Residue of Malathion and its Metabolite Malaoxon
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43383401 Bookbinder, M. (1994) Magnitude of the Residue of Malathion and its Metabolite Malaoxon
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43383501 Bookbinder, M. (1994) Magnitude of the Residue of Malathion and its Metabolite Malaoxon
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Analytical Labs.
43414901 Bookbinder, M. (1994) Magnitude of the Residue of Malathion and its Metabolite Malaoxon
in/on Spring Wheat Raw Agricultural Commodities Harvested After Ground and Aerial
Treatment: Lab Project Number: AA920124: 92-0060. Unpublished study prepared by
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43417601 Bookbinder, M. (1994) Magnitude of the Residue of Malathion and its Metabolite Malaoxon
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92-0034. Unpublished study prepared by American Agricultural Services and EN-CAS
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43451701 Bookbinder, M. (1994) Magnitude of the Residue of Malathion and Its Metabolite Malaoxon
in Orange Processed Commodities: Lab Project Number: AA920129: 92-0074. Unpublished
study prepared by American Agricultural Services, Inc.; EN-CAS Analytical Labs; and The
National Food Laboratory, Inc.
43468101 Bookbinder, M. (1994) Magnitude of the Residue of Malathion and Its Metabolite Malaoxon
in/on Rice Raw Agricultural Commodities Harvested After Ground and Aerial Treatment:
Amended Report: Lab Project Numbers: AA920120: 92-0039. Unpublished study prepared
by American Agricultural Services, Inc. and EN-CAS Analytical Labs.
43468201 Bookbinder, M. (1994) Magnitude of the Residue of Malathion and Its Metabolite Malaoxon
in/on Field Corn Raw Agricultural Commodities Harvested After Ground and Aerial
Treatment: Lab Project Numbers: AA920108: 92-0046: AA920108.IA. Unpublished study
prepared by American Agricultural Services, Inc.; and EN-CAS Anlaytical Labs.
43499901 Bookbinder, M. (1994) Magnitude of the Residue of Malathion and Its Metabolite Malaoxon
in/on Tomato Processed Commodities: Lab Project Number: AA920135: 92-0079.
Unpublished study prepared by American Agricultural Services, Inc.; The National Food
Lab, Inc.; and EN-CAS Analytical Labs.
43501501 Beavers, J.; Haberlein, D.; Mitchell, L.; et al. (1995) Malathion: A One-generation
Reproduction Study with the Northern Bobwhite (Colinus virginianus): Lab Project Number:
232-112A. Unpublished study prepared by Wildlife International, Ltd.
43510501 Bookbinder, M. (1995) Magnitude of the Residue of Malathion and Its Metabolite Malaoxon
in/on Winter Wheat Processed Commodities: Lab Project Number: 92-0080: AA920136:
EL6110. Unpublished study prepared by American Agricultural Services, Inc.; EN-CAS
Analytical Labs; and Texas A&M University.
43524101 Bookbinder, M. (1995) Magnitude of the Residue of Malathion and its Metabolite Malaoxon
in/on Potato Processed Commodities: Lab Project Number: AA920138: 92/0075.
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170
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43545201 Bookbinder, M. (1995) Magnitude of the Residue of Malathion and its Metabolite Maloxon
in/on Clover Raw Agricultural Commodities Harvested after Ground and Aerial Treatment:
Lab Project Number: AA920107: 94-0044. Unpublished study prepared by American
Agricultural Services, Inc. and EN-CAS Analytical Labs.
43546101 Bookbinder, M. (1995) Magnitude of the Residue of Malathion and Its Metabolite Malaoxon
in/on Alfalfa Raw Agricultural Commodities Harvested after Ground and Aerial Treatment:
Lab Project Number: AA920101: 92-0031: AA920101.CA1. Unpublished study prepared by
American Agricultural Services, Inc. and EN-CAS Analytical Labs.
43548401 Bookbinder, M. (1995) Magnitude of the Residue of Malathion and Its Metabolite Malaoxon
in/on Grape Processed Commodities: Lab Project Number: 92-0073: AA920133:
AA920133.CA1. Unpublished study prepared by American Agricultural Services, Inc.; The
National Food Lab, Inc.; and EN-CAS Analytical Labs.
43549001 Clayton, B. (1995) Stability of Malathion and Malaoxon in Various Raw Agricultural Crop
Commodities During Six Months of Frozen Storage: (Final Report): Lab Project Number:
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43562301 Bookbinder, M. (1995) Magnitude of the Residue of Malathion and Its Metabolite Malaoxon
in/on Rice Processed Commodities: Lab Project Numbers: AA920137: 92-0077:
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43577401 Bookbinder, M. (1995) Magnitude of the Residue of Malathion and its Metabolite Malaoxon
in/on Field Corn Processed Commodities: Lab Project Number: AA920132: 92-0072:
AA920132.TX1. Unpublished study prepared by American Agricultural Service, Inc.; Texas
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43585301 Bookbinder, R. (1995) Magnitude of the Residue of Malathion and Its Metabolite Malaoxon
in/on Cottonseed Processed Commodities: Lab Project Number: AA920131: 92-0071:
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43596601 Bookbinder, M. (1995) Magnitude of the Residue of Malathion and Its Metabolite Malaoxon
in/on Cottonseed Harvested after Ground and Aerial Treatment: Lab Project Number: 92-
0033: AA920110: AA920110.AZ1. Unpublished study prepared by American Agricultural
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43630301 Humble, G.; Herzig, R. (1995) Independent Laboratory Validation of the Pesticide Analytical
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22/94: AA/920117. Unpublished study prepared by AGVISE Labs, Inc. 376 p.
43661401 Rice, F.; Williams, B. (1995) Magnitude of the Malathion and Malaoxon Residues in or on
Stored Wheat Grain and Aspirated Grain Fractions: Lab Project Numbers: 41701: FS-
41701.SG: ABC 41701. Unpublished study prepared by ABC Labs., Inc.
43666801 Rice, F. (1995) Magnitude of the Malathion and Malaoxon Residues in or on Stored Corn
Grain and Processed Commodities: Final Report: Lab Project Number: 41702: FS-41702.
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171
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43684801 Clayton, B. (1995) Stability of Malathion and Malaoxon in Various Processed Commodities
During Six Months of Frozen Storage: Lab Project Number: 93-0038B. Unpublished study
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43868601 Nixon, W. (1995) Column Leaching of (carbon 14)-Malathion in Four Soil Types Following
Aerobic Aging: Lab Project Number: 951: 1842. Unpublished study prepared by PTRL East,
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43910901 Clayton, B. (1996) Stability of Malathion and Malaoxon in Various Raw Agricultural and
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43942901 Daly, I. (1996) A 24-Month Oral Toxicity/Oncogenicity Study of Malathion in the Rat via
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43975201 Daly, I. (1996) A 24-Month Oral Toxicity/Oncogenicity Study of Malaoxon in the Rat via
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43991401 Samoil, K. (1996) Magnitude of Residue: Malathion on Flax: Lab Project Number: 04795:
04795.94-ND02: 4795.94-NDR03. Unpublished study prepared by North Dakota State
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44001101 Samoil, K. (1996) Magnitude of Residue: Malathion on Mushroom: Lab Project Number: PR
4816: 04816: PR 04816. Unpublished study prepared by Interregional Research Project No.
4.
44009601 Samoil, K. (1996) Magnitude of Residue: Malathion on Apple: Lab Project Number: 04768:
04768.94-CA77: 04827.94-CA79. Unpublished study prepared by Interregional Research
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44013701 Samoil, K. (1996) Magnitude of Residue: Malathion on Pear: (Final Report): Lab Project
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44016001 Samoil, K. (1996) Magnitude of Residue: Malathion on Peach: Lab Project Number: PR
04826: 04826.90-GA20: 04826.92-MI11. Unpublished study prepared by Interregional
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44061201 Samoil, K. (1996) Magnitude of Residue: Malathion on Fig: Lab Project Number: 4793:
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44076801 Samoil, K. (1996) Magnitude of Residue: Malathion on Macadamia: (Final Report): Lab
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44094401 Samoil, K. (1996) Magnitude of Residue: Malathion on Strawberry: (Final Report): Lab
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44094801 Samoil, K. (1996) Magnitude of Residue: Malathion on Watercress: (Final Report): Lab
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172
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44098401 Samoil, K. (1996) Magnitude of Residue: Malathion on Melon: (Final Report): Lab Project
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44120001 Samoil, K. (1996) Magnitude of Residue: Malathion on Apricot: Lab Project Number: PR
04769: 04769.93-CA48: 04769.93-CAR16. Unpublished study prepared by Interregional
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44124801 Samoil, K. (1996) Magnitude of Residue: Malathion on Mint: Lab Project Number: PR
04829: 4829.93-WI19: 4829.93-CAR09. Unpublished study prepared by Interregional
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44203901 Samoil, K. (1997) Magnitude of Residue: Malathion on Broccoli: (Final Report): Lab Project
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44205901 Samoil, K. (1997) Magnitude of Residue: Malathion on Pea (Succulent): Lab Project
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44232601 Samoil, K. (1996) Magnitude of Residue: Malathion on Cabbage: (Final Report): Lab Project
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44232701 Samoil, K. (1997) Magnitude of Residue: Malathion on Okra: Lab Project Number: 04820:
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44266401 Samoil, K. (1997) Magnitude of Residue: Malathion on Turnip: Lab Project Number: 04847:
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44271101 MSamoil, K. (1997) Magnitude of Residue: Malathion on Mustard Greens: Lab Proj ect
Number: 04817: 4817.92-AZ02: 4817.92-SC05. Unpublished study prepared by
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44272401 Samoil, K. (1997) Magnitude of Residue: Malathion on Spinach: Lab Project Number:
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44282101 Samoil, K. (1997) Magnitude of Residue: Malathion on Raspberry: (Amended Draft Report):
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44383301 Samoil, K. (1997) Magnitude of Residue: Malathion on Walnut: (Final Report): Lab Project
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Kucera, Emil.1987. Brain Cholinesterase Activity in Birds After a City-Wide Aerial Application
of Malathion. Manitoba Dept. of Environment and Workplace Safety and Health.
Kuhajda, B.R. et al 1996. Impact of Malathion on Fish and Aquatic Invertebrate Communities
and on Acetylcholinesterase Activity in Fishes in Stewart Creek, Fayette County, Alabama. ,
Dept. Of Biological Sciences, University of Alabama,
Marliac and Mutchler, 1963. In other studies where malathion was injected into eggs at 50
mg/egg chicks showed shortening of legs and bleaching of feathers .
181
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McEwen, Lowell and Robert L. Brown. 1966. Acute Toxicity of Dieldrin and Malathion to Wild
Sharp-tailed Grouse.Journal of Wildlife management. Vol. 30, No. 3, July 1966. MRID 113233
Mehrotra, K. N. et al, 1966. Physiological Effects of Malathion on the House Sparrow Passer
domesticus.Indian Agricultural Research Institute Delhi, India.
Mitchell and Yutema, 1973. Teratogenic Effects of Malathion and Captan in the Embryo of
Common Snapping Turtle.
Mount, Donald I. and Charles Stephan, 1967. A Method for Establishing Acceptable Toxicant
Limits for Fish - Malathion and Butoxyethanol Ester of 2, 4-D -U.S. Dept of Interior.
Oshima, R. S. 1982 California Medfly Report.
Parkhurst, Zell and Harlan Johnson. 1955. Toxicity of Malathion 500 to fall Chinook Salmon
Fingerlings. USFWS, (Progressive Fish Culturist) .
Parrish, Patrick R., et al., 1977. Chronic Toxicity of Methoxychlor, Malathion, and Carbofuran
to Sheepshead Minnow (Cyprinodon variegatus), EG & G Bionomics Marine Research
Laboratory, Pensacola, Fla. EPA-600/3-77-059. May 1977.
Parsons, Jack K. and Billy Don Davis, 1971. The Effects on Quail, Migratory Birds and Non-
Game Birds from Application of Malathion and Other Insecticides. Texas Parks and Wildlife
Dept., Study conducted from 1964 to 1968.
Pawar, Keshore R., et al, 1983. Effect of Malathion on Embryonic Development of the Frog
Microhyla ornata (Dumeril and Bibron). Department of Zoology, University of Poona, India.
Bulletin of Environmental Contamination and Toxicology, Volume 31. 170-176.
Post, George and Robert Leasure., 1974. Sublethal Effects of Malathion to Three Salmonid
Species. Colorado State University .
Proctor, Raphael R. Jr., Jane P. Corliss, and Donald Lightner 1966. Mortality of Post larval and
Juvenile Shrimp Caused by Exposure to Malathion -A Laboratory and Field Study. National
Marine Fisheries Service, Galveston Laboratory.
Rosenbaum, E.A. et al. 1988. Early Biochemical Changes Produced by Malathion on
Developing Toad Embryos. Archives of Environmental Contamination and Toxicology.
Volume 17 831-83 5.
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182
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Tagatz, M.E., 1974. Effects of Ground Application of Malathion on Saltmarsh Environments In
Northwestern Florida. USEPA Gulfbreeze, Environmental Research Laboratory, Gulfbreeze,
Florida.
USD A, Environmental Monitoring report. Cooperative Medfly Project Florida, 1997. Spray
Operations Hillsborough Area. USDA Report.
Weis, Peddrick and Judith Weiss, 1975.Abnormal Locomotion Associated with Skeletal
Malformations in Sheepshead minnow. Rutgers University and New York Ocean Science
Laboratory, Montauk, New York.
Walker, W.W. and Stojanovic, B.J., 1974. Malathion degradation by an Arthrobacter species. J.
Environ Quality. 3. 4-10.
Walker, W.W. and Stojanovic, B.J., 1973. Microbial versus chemical degradation of malathion
in soil. J. Environ Quality. 2. 229-232.
Woodward, Dan F.,, 1969. Sport Fisheries Research USFWS, Publication 77.
Author Anonymous, 1967. Quarterly Report - USFWS Research Laboratory, Columbia, Mo..
Author Anonymous, 1970. USFWS Sport Fisheries Research Report Publication 106, Wash.
DC.
Bender, Michael E., 1969. The Toxicity of the Hydrolysis and Breakdown Products of Malathion
to Fathead minnow - University of Michigan.
Bender, Michael E. 1969. Uptake and Retention of Malathion by the Carp. University of
Michigan.
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Mudminnow Umbra pygmaea , Virginia Institute of Marine Science.
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Squawfish exposed to Carbaryl and Malathion.
Beyers, P. 1993. Acetylcholinesterase Inhibition in Federally Endangered Bonytail Chub
Exposed to Carbaryl and Malathion.
Bookhout, Cazlyn G. and John D. Costlow Jr., 1976. Effects of Mirex, Methoxychlor and
Malathion on Development of Crabs., Duke University and Gulfbreeze Laboratory (USEPA) Pg.
53-69.
183
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Bourke, J.B. et al, 1968. Comparative Metabolism of Malathion - CM in Plants and Animals.
New York State Agricultural Experiment Station, Cornell University.
Bourquin, Al W. 1975. Microbial-Malathion Interaction in Artificial Saltmarsh Ecosystems.
Gulfbreeze Laboratory, USEPA.
California-Administrative Report 82-2, 1982. Monitored aquatic incidents during broadscale
aerial application over San Francisco, Bay area ,1981., Dept. Of Fish and Game, Environmental
Services Branch.
Cook, Gary H. and James C. Moore, 1976. Determination of Malathion, Malaoxon, and Mono-
and Dicarboxylic Acids of Malathion in Fish, Oyster,and Shrimp Tissue. USEPA Gulfbreeze
Laboratory.
Conte, Fred S. and Jack C. Parker, 1975. Effect of Aerially Applied Malathion on Juvenile
Brown and White Shrimp, Penaeus aztecus and Penaeus setiferus. - Texas A&M University
(Am. Fisheries Society).
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Dahlsten, Donald L. 1983. Effects of Malathion Bait Spray for Mediterranean Fruit Fly on Non-
target Organisms on Urban Trees in Northern California., University of California.
Darsie, Richard and Coraiden, F. Eugene, 1958. Malathion Toxicity to Killifish in Delaware.
Delaware Agricultural Research Station.
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Cells. Division of Hygienic Biology, Budapest, Hungary.
Dieter, Michael P., 1975 Use of Enzyme Profiles to Monitor Residues in Wildlife.USFWS,
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Dunachie and Fletcher, 1969. (Walker (1971)Khera and Lyon(1968)
A number of studies were conducted where malathion or malaoxon were injected into chick
embryos,). Malaoxon caused reduced survival of embryos at a concentration of 30 micromoles,
and those that did survive had severe abnormalities. Malathion at 30 and 15 micromoles
produced less severe abnormalities.
184
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Experimental Program to Control The Melon Fly. U.S. Fish and Wildlife Service, Honolulu,
Hawaii.
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From Broadscale Aerial Malathion Applications in South San Francisco Bay Region,, Pesticide
Investigation Unit, Water Pollution Control Laboratory, California Fish and Game Department.
Gary, Norman E. and Eric C., Mussen. 1984. Impact of Mediterranean Fruit Fly Malathion Bait
Spray on Honeybees. Dept. of Entomology, Univ. of California, Davis.
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Organophosphorous Pesticides, Environmental Pollution (Ser. A) 28:45-52
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County Texas. Journal of Med Entomology.
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Species of Stonefly Naiads. , Dept. Zoology, University of Utah. (MRID 00065497)
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Johansen, C.A. et al. 1965. Bee Poisoning Hazard of Undiluted Malathion Applied to Alfalfa in
Bloom. Washington State University College of Agriculture.
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Keller, Anne E. , 1995. Toxicity of Malathion to Native Freshwater Mussels.National Biological
Survey Laboratory, Gainesville, Florida.
Kennedy, Harry D. and David Walsh. 1970. Effects of Malathion on Two Warmwater Fishes
and Aquatic Invertebrates in Ponds. USFWS, Fish Pesticide Research Laboratory, Columbia,
Mo.,
Kucera, Emil.1987. Brain Cholinesterase Activity in Birds After a City-Wide Aerial Application
of Malathion. Manitoba Dept. of Environment and Workplace Safety and Health.
Kuhajda, B.R. et al 1996. Impact of Malathion on Fish and Aquatic Invertebrate Communities
and on Acetylcholinesterase Activity in Fishes in Stewart Creek, Fayette County, Alabama. ,
Dept. Of Biological Sciences, University of Alabama,
Marliac and Mutchler, 1963. In other studies where malathion was injected into eggs at 50
mg/egg chicks showed shortening of legs and bleaching of feathers.
McEwen, Lowell and Robert L. Brown. 1966. Acute Toxicity of Dieldrin and Malathion to Wild
Sharp-tailed Grouse.Journal of Wildlife management. Vol. 30, No. 3, July 1966. MRID 113233
Mehrotra, K. N. et al, 1966. Physiological Effects of Malathion on the House Sparrow Passer
domesticus.Indian Agricultural Research Institute Delhi, India.
Mitchell and Yutema, 1973. Teratogenic Effects of Malathion and Captan in the Embryo of
Common Snapping Turtle.
Mount, Donald I. and Charles Stephan, 1967. A Method for Establishing Acceptable Toxicant
Limits for Fish - Malathion and Butoxyethanol Ester of 2, 4-D -U.S. Dept of Interior.
Oshima, R. S. 1982 California Medfly Report.
Parkhurst, Zell and Harlan Johnson. 1955. Toxicity of Malathion 500 to fall Chinook Salmon
Fingerlings. USFWS, (Progressive Fish Culturist) .
Parrish, Patrick R., et al., 1977. Chronic Toxicity of Methoxychlor, Malathion, and Carbofuran
to Sheepshead Minnow (Cyprinodon variegatus), EG & G Bionomics Marine Research
Laboratory, Pensacola, Fla. EPA-600/3-77-059. May 1977.
186
-------
Parsons, Jack K. and Billy Don Davis, 1971. The Effects on Quail, Migratory Birds and Non-
Game Birds from Application of Malathion and Other Insecticides. Texas Parks and Wildlife
Dept, Study conducted from 1964 to 1968.
Post, George and Robert Leasure., 1974. Sublethal Effects of Malathion toThree Salmonid
Species. Colorado State University .
Proctor, Raphael R. Jr., Jane P. Corliss, and Donald Lightner 1966. Mortality of Post larval and
Juvenile Shrimp Caused by Exposure to Malathion -A Laboratory and Field Study. National
Marine Fisheries Service, Galveston Laboratory.
Rong, Suriyam, Y. et al, 1968. Effects of Insecticides on Feeding Activity of the Guppy, a
Mosquito-eating Fish in Thailand - World Health Organization.
Tagatz, M.E., 1974. Effects of Ground Application of Malathion on Saltmarsh Environments In
Northwestern Florida. USEPA Gulfbreeze, Environmental Research Laboratory, Gulfbreeze,
Florida.
USD A, Environmental Monitoring report. Cooperative Medfly Project Florida, 1997. Spray
Operations Hillsborough Area. USDA Report.
Weis, Peddrick and Judith Weiss, 1975.Abnormal Locomotion Associated with Skeletal
Malformations in Sheepshead minnow. Rutgers University and New York Ocean Science
Laboratory, Montauk, New York.
Walker, W.W. and Stojanovic, B.J., 1974. Malathion degradation by an Arthrobacter species. J.
Environ Quality. 3. 4-10.
Walker, W.W. and Stojanovic, B.J., 1973. Microbial versus chemical degradation of malathion
in soil. J. Environ Quality. 2. 229-232.
Woodward, Dan F., 1969. Sport Fisheries Research USFWS, Publication 77.
Author Anonomous,1967. Quarterly Report - USFWS Research Laboratory, Columbia, Mo..
Author Anonomous, 1970. USFWS Sport Fisheries Research Report Publication 106, Wash.
DC.
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