United States
Environmental Protection
Agency
Prevention, Pesticides
And Toxic Substances
(7508W)
EPA-738-F-95-017
July 1995
&EPA R.E.D. FACTS
Fenitrothion
Pesticide
Reregistration
Use Profile
Regulatory
History
All pesticides sold or distributed in the United States must be
registered by EPA, based on scientific studies showing that they can be used
without posing unreasonable risks to people or the environment. Because of
advances in scientific knowledge, the law requires that pesticides which
were first registered years ago be reregistered to ensure that they meet
today's more stringent standards.
In evaluating pesticides for reregistration, EPA obtains and reviews a
complete set of studies from pesticide producers, describing the human
health and environmental effects of each pesticide. The Agency imposes
any regulatory controls that are needed to effectively manage each
pesticide's risks. EPA then reregisters pesticides that can be used without
posing unreasonable risks to human health or the environment.
When a pesticide is eligible for reregistration, EPA announces this and
explains why in a Reregistration Eligibility Decision (RED) document. This
fact sheet summarizes the information in the RED document for
reregistration case 0445, fenitrothion.
Fenitrothion is an organophosphate insecticide and acaricide used for
commercial greenhouse and outdoor use on ornamentals, including trees, to
control a variety of insects and mites. Fenitrothion also is marketed in two
new bait products used to control ants and roaches in and around homes,
stores, restaurants, warehouses, and other sites. Two mosquito control
products used in other countries (not in the U.S.) to prevent malaria are
being voluntarily cancelled by the manufacturer. No food or feed uses are
registered, however a food additive regulation is established for residues of
fenitrothion in or on wheat gluten imported from Australia.
Fenitrothion is applied to ornamentals using ground-based and hand-
held equipment. Annual usage on ornamentals is small and appears to be
decreasing. Fenitrothion formulations include a wettable powder,
emulsifiable concentrate, and bait.
Fenitrothion was first registered as a pesticide in the U.S. in 1975, for
control of the spruce budworm in forests. EPA issued a Data Call-In (DCI)
in 1984 requiring additional chronic toxicity data, and a Registration
Standard in July 1987 (PB88-191697) which evaluated the studies submitted
in response to the DCI. Certain label restrictions were necessary including
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a 24-hour interim reentry interval for greenhouse and nursery ornamental
uses, and restricted-use classification for the forestry uses. EPA issued a
second DCI in June 1991, and required labeling to reflect the high toxicity
to birds, honeybees, and aquatic invertebrates. Precautions were imposed to
protect endangered species. The registrant requested cancellation of the
forestry uses in 1992.
Through implementation of the labeling requirements of the 1992
Worker Protection Standard for Agricultural Pesticides (WPS), the 24-hour
interim reentry interval was converted to a 24-hour interim restricted entry
interval. Uses within the scope of the WPS include all commercial and
research uses of fenitrothion to produce agricultural plants, including use on
ornamentals. Fenitrothion ant and roach bait products, registered in January
1995, fall outside the scope of the WPS.
The Agency currently is requiring additional exposure data for
fenitrothion before it can make a regulatory decision on the eligibility of low
pressure hand wand and knapsack/backpack methods of application. Six
fenitrothion products are eligible for reregistration.
Human Health Toxicity
Assessment In studies using laboratory animals, fenitrothion generally has been
shown to be of moderate to high acute toxicity. It is moderately toxic by
the acute oral and dermal routes and has been placed in Toxicity Category n
(the second highest of four categories) for this effect. It is slightly toxic for
acute eye effects and is a mild dermal irritant (Toxicity Category HI).
Fenitrothion is not a skin sensitizer.
Fenitrothion is classified as a Group E carcinogen, indicating that it is
non-carcinogenic to humans. It is a cholinesterase inhibitor as indicated in
several chronic and subchronic toxicity tests performed on laboratory
animals.
Studies indicate that fenitrothion does not cause reproductive effects.
Fenitrothion is not considered to be a mammalian mutagen. Metabolism
studies indicate that fenitrothion is excreted in the urine and feces within
seven days of exposure.
A rat study did not indicate ocular toxicity. A six-month ocular study
on dogs, required by the 1991 DCI, is in reserve status until a test protocol
is developed.
Dietary Exposure
Although no food uses currently are registered, people may be
exposed to residues of fenitrothion through the diet. A food additive
regulation for fenitrothion and two of its metabolites has been established
(40 CFR 185.2200(a)) for residues in wheat gluten resulting from
postharvest application of the insecticide to stored wheat in Australia. An
acute risk to the U..S. population from consumption of Australian wheat
gluten is unlikely because gluten is mixed with flour before it is eaten.
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Since fenitrothion is not registered for use on any domestic crops, its
residues are not expected to enter the diet of food animals in the U.S..
EPA developed a U.S. consumption estimate for Australian wheat
gluten, and assessed dietary exposure and risk posed by fenitrothion residues
in that commodity. For the overall U.S. population, such exposure
represents 3% of the Reference Dose (RfD), or amount believed not to
cause adverse effects if consumed daily over a 70-year lifetime. The
exposure level of the most highly exposed subgroup, children aged 1
through 6, represents 8% of the RfD. If the food additive regulation of 30
ppm is used instead of EPA's consumption estimate, these exposure and risk
estimates are doubled to 7% of the RfD for the overall U.S. population and
15% of the RfD for children aged 1 through 6. Dietary exposure and risk
are minimal.
Occupational and Residential Exposure
Based on current use patterns, fenitrothion handlers (mixers, loaders,
and applicators) may be exposed to this pesticide during and after normal
use. Exposure to fenitrothion is most likely to occur during and after its
application to ornamentals, either outdoors or in greenhouses. The primary
route of occupational exposure is dermal. Inhalation exposure may be
acute, intermittent, or chronic.
Although most of the exposure data available were questionable, EPA
assessed worker exposure and risk to fenitrothion using the lexicological
endpoints dermal toxicity resulting from intermediate exposure, and
inhalation toxicity resulting from chronic exposure, both of which may
result in cholinesterase inhibition. Exposure estimates are based on the
assumption that fenitrothion handlers wear certain personal protective
equipment. Margins of Exposure (MOEs) are less than 100 (the margin
believed sufficiently protective) for applicators using low pressure
handwands and for mixer/loader/applicators using low-pressure or
knapsacl^ackpack equipment. Due to a lack of post-application exposure
data, EPA was unable to estimate exposure or risk to workers following use
of fenitrothion on ornamentals.
Because they are formulated as enclosed baits, the two fenitrothion ant
and roach control products approved in early 1995 for residential use result
in considerably less human exposure than the ornamental uses, during and
after application.
Human Risk Assessment
Based on the available toxicity studies, EPA has determined that
fenitrothion presents a potential acute health hazard. It is of moderate to
high acute toxicity and is a cholinesterase inhibitor. However, it has been
classified as non-carcinogenic to humans ("Group E"). Dietary exposure to
fenitrothion residues in wheat gluten is extremely low, and dietary risk
appears to be minimal.
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Of greater concern is the risk posed to fenitrothion handlers,
particularly mixers/loaders/applicators using low pressure handwands or
knapsackftackpack equipment to treat ornamentals. The MOEs for these
handlers are inadequate. EPA is deferring a regulatory decision for
fenitrothion products applied using these methods until chemical-specific
worker exposure studies, due within one year, are submitted. Thus, for
ornamentals, high pressure handwand treatment is the only application
method eligible for reregistration at this time.
EPA is employing a number of risk mitigation measures to protect
fenitrothion handlers. For example, the Agency is requiring "baseline"
personal protective equipment (PPE); a 48-hour restricted-entry interval
(REI) which is more stringent than the (24-hour) interim REI set by the
Worker Protection Standard for Agricultural Pesticides (WPS); and
upgraded PPE for early entry. The 48-hour REI is increased to 72 hours
when any fenitrothion product is used in an outdoor area where the average
rainfall is less than 25 inches per year. (See RED Risk Mitigation and
Labeling sections for more details.)
Environmental Environmental Fate Assessment
Assessment Fenitrothion's major routes of dissipation are biotic microbial
mediated processes to carbon dioxide and abiotic aquatic photolysis.
Fenitrothion appears to be non-mobile when applied to silty clay loam, silty
clay, and sandy loam soils. It appears to dissipate fairly rapidly with a half
life of 3 to 25 days, and does not appear to be mobile. Fenitrothion is
expected to be slightly persistent and relatively non-mobile in the soil
environment. Its metabolites also appear to degrade fairly rapidly to carbon
dioxide, and are relatively non-mobile. Residues do not leach below 0-12
inches soil depth.
Ecological Effects
Fenitrothion is highly toxic to birds on an acute basis, and causes
chronic effects (reduced egg production) in reproduction studies using
bobwhite quail. It is moderately toxic to small mammals and both cold and
warm water fish on an acute basis. However, it is highly toxic to aquatic
invertebrates, and moderately to very highly toxic to estuarine organisms.
It also is highly toxic to bees.
Ecological Effects Risk Assessment
High acute risk is expected for birds consuming grass and insects, and
high chronic risk to seed-, insect-, and grass-eating birds will occur,
following single as well as multiple applications of fenitrothion at 3 Ibs.
active ingredient (ai)/acre. Risk quotients for mammals and estuarine/
marine organisms are exceeded. High acute risk to freshwater invertebrates
is expected from a single application of fenitrothion. Honey bees exposed to
this pesticide may be adversely effected.
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To reduce these risks, the registrant has proposed numerous label
modifications for products used on ornamentals including a lower use rate, a
restriction on the maximum number of applications per year, and an
increase in the retreatment interval from one week to one month. (See Risk
Mitigation, below.)
Endangered species levels of concern (LOCs) are exceeded for acute
effects to aquatic invertebrates and in some instances to birds and wild
mammals, as well as for chronic effects to birds and aquatic invertebrates.
Limitations on the use of fenitrothion may be required in the future to
protect threatened and endangered species when the Endangered Species
Protection Program goes into effect.
Risk Mitigation To lessen the acute toxicity risks of fenitrothion, EPA, in conjunction
with the registrant, has developed and is requiring the following risk
mitigation measures.
o All fenitrothion products labeled for outdoor use must be classified as
restricted use pesticides.
o Use of fenitrothion on Christmas tree plantations, on shade trees other
than those in nurseries, and basal bark (drench) treatment are being
voluntarily deleted from product labels by the registrant. These uses pose
the greatest potential for exposure to non-target species.
o For the remaining ornamental uses, the registrant has proposed
significant label revisions to reduce ecological risk, including:
• Reduce application rate to 0.3125 Ibs./acre;
• Reduce maximum number of applications to three per year;
• Increase minimum interval between applications to one month;
• Remove broadcast application from the label, limiting use to spot
treatment only.
o Due to concerns about the high acute toxicity of fenitrothion, EPA is
establishing baseline personal protective equipment (PPE) requirements for
handlers of all end-use products, and is establishing early-entry PPE
requirements including dermal protection PPE and protective eyewear.
o Due to concerns about the post-application exposure of agricultural
workers, EPA is increasing the interim Restricted Entry Interval (REI) from
24 to 48 hours for all uses within the scope of the WPS. This REI is further
increased to 72 hours when fenitrothion products are used outdoors in areas
where the average rainfall is less than 25 inches per year. The REI will be
reassessed upon receipt and review of the chemical specific exposure data
required in the RED.
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Additional Data EPA is requiring the following additional generic studies for
Required fenitrothion to confirm its regulatory assessments and conclusions:
- Acute oral LD50 for Bobwhite Quail (3-methyl-nitrophenol);
- Terrestrial Field Dissipation;
- Chronic Toxicity to Birds (reserved);
- Six Month Ocular Toxicity Study in Dogs (reserved).
Before EPA can make a reregistration eligibility decision regarding
the low pressure handwand and knapsack/backpack methods of application,
the following studies must be submitted:
- Foliar Dissipation;
- Occupational Post-application Dermal Exposure;
- Occupational Post-application Inhalation Exposure;
- Estimation of Dermal Exposure at Outdoor Sites;
- Estimation of Inhalation Exposure at Outdoor Sites;
- Estimation of Dermal Exposure at Indoor Sites;
- Estimation of Inhalation Exposure at Indoor Sites.
The Agency also is requiring product-specific data including product
chemistry and acute toxicity studies, revised Confidential Statements of
Formula (CSFs), and revised labeling for reregistration.
Product Labeling
Changes
Required
All fenitrothion end-use products must comply with EPA's current
pesticide product labeling requirements, and with the following. For a
comprehensive list of labeling requirements, please see the fenitrothion RED
document.
Restricted Use Classification
All fenitrothion products labeled for outdoor use must be classified for
restricted use, and the following statement must appear on product labels:
"Restricted Use Pesticide
Due to toxicity to fish and aquatic organisms.
For retail sale to and use only by certified applicators or persons
under their direct supervision and only for those uses covered by the
certified applicator's certification."
Changes in Rates, Uses, and Number of Applications
The following changes must be made to all ornamental end-use products:
- Restricted use classification;
- Delete Christmas tree farm and Southern Pine Bark Beetle uses;
- Delete broadcast application-all ornamental uses are limited to spot
treatments;
- Limit use rate to 0.3125 Ibs ai/acre and limit the maximum number
of applications per year to three;
- Increase the minimum interval between applications ,to one month;
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- Limit use on shade trees to those in nurseries and/or greenhouses;
- Limit application to high pressure handwands, low pressure
handwands, and knapsack/backpack sprayers. .
Personal Protective Equipment (PPE) Requirements
The following minimum, baseline PPE requirements pertain to both WPS
and nonWPS uses by occupational handlers:
"Applicators must wear:
- Coveralls over long-sleeved shirt and long pants;
- Chemical-resistant gloves;
- Chemical-resistant footwear plus socks;
- Chemical-resistant headgear for overhead exposure;
- Chemical-resistant apron when cleaning equipment, mixing, or
loading;
- Dust/mist filtering respirator (MSHA/NIOSH approval number
prefix TC-21C)."
Entry Restrictions
EPA is requiring the following entry restrictions for all uses within the
scope of the WPS:
"Do not enter or allow worker entry into treated areas during the
restricted entry interval (REI) of 48 hours. Each 48-hour REI is
increased to 72 hours in outdoor areas where the average rainfall is
less than 25 inches per year."
The PPE required for early entry following applications of fenitrothion is:
- Coveralls over long-sleeved shirt and long pants;
- Chemical-resistant gloves;
- Chemical-resistant footwear plus socks;
- Chemical-resistant headgear for overhead exposures; and
- Protective eyewear.
User Safety Statements
EPA is requiring the following user safety statement on all end-use products
containing fenitrothion:
User Safety Requirements:
"Discard clothing and other absorbent materials that have been
drenched or heavily contaminated with this product's concentrate. Do
not reuse them. Follow manufacturer's instructions for
cleaning/maintaining PPE. If no such instructions exist for washables,
use detergent and hot water. Keep and wash PPE separately from
other laundry."
User Safety Recommendations:
"Users should wash hands before eating, drinking, chewing gum,
using tobacco, or using the toilet."
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"Users should remove clothing 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."
Environmental Hazard
The following statement is required for end-use products:
"ENVIRONMENTAL HAZARD
This pesticide is toxic to birds and aquatic 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. Runoff may be
hazardous to aquatic organisms in neighboring areas. Do not
contaminate water when disposing of equipment washwater or
rinsate."
Regulatory
Conclusion
For More
Information
EPA has determined that products containing fenitrothion are eligible
for reregistration except products labeled for application to ornamentals
using low pressure handwand and knapsack/backpack spray equipment
(products applied using high pressure handwand equipment are eligible for
reregistration). The use of eligible fenitrothion products in accordance with
labeling and risk mitigation measures specified in this RED will not pose
unreasonable adverse effects to humans or the environment. These products
will be reregistered once the required confirmatory generic data, product
specific data, CSFs, and revised labeling are received and accepted by EPA.
EPA does not have enough information at this time to make an
eligibility decision for fenitrothion products labeled for use on ornamentals
and applied using low pressure handwand and knapsack/backpack spray
equipment. The Agency is requiring additional worker exposure studies in
order to develop a more complete data base and make a reregistration
eligibility decision regarding these uses of fenitrothion.
EPA is requesting public comments on the Reregistration Eligibility
Decision (RED) document for fenitrothion during a 60-day time period, as
announced in a Notice of Availability published in the Federal Register. To
obtain a copy of the RED document or to submit written comments, please
contact the Pesticide Docket, Public Response and Program Resources
Branch, Field Operations Division (7506C), Office of Pesticide Programs
(OPP), US EPA, Washington, DC 20460, telephone 703-305-
5805.
Electronic copies of the RED and this fact sheet can be downloaded
from the Pesticide Special Review and Reregistration Information System at
703-308-7224. They also are available on the Internet on EPA's gopher
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server, GOPHER.EPA.GOV, or using ftp on FTP.EPA.GOV, or using
WWW (World Wide Web) on WWW.EPA.GOV.
Printed copies of the RED and fact sheet can be obtained from EPA's
National Center for Environmental Publications and Information
(EPA/NCEPI), PO Box 42419, Cincinnati, OH 45242-0419, telephone
513-489-8190, fax 513-489-8695.
Following the comment period, the fenitrothion RED document also
will be available from the National Technical Information Service (NTIS),
5285 Port Royal Road, Springfield, VA 22161, telephone 703-487-4650.
For more information about EPA's pesticide reregistration program,
the fenitrothion RED, or reregistration of individual products containing
fenitrothion, please contact the Special Review and Reregistration Division
(7508W), OPP, US EPA, Washington, DC 20460, telephone
703-308-8000.
For information about the health effects of pesticides, or for assistance
in recognizing and managing pesticide poisoning symptoms, please contact
the National Pesticides Telecommunications Network (NPTN). Call toll-
free 1-800-858-7378, between 8:00 am and 8:00 pm Eastern Standard
Time, Monday through Friday.
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